LAN8740A/LAN8740Ai
Small Footprint MII/RMII 10/100 Energy
Efficient Ethernet Transceiver with HP
Auto-MDIX and flexPWR® Technology
PRODUCT FEATURES
Datasheet
Highlights
Key Benefits
Single-Chip Ethernet Physical Layer Transceiver
(PHY)
Compliant with Energy Efficient Ethernet 802.3az
Cable diagnostic support
Wake on LAN (WoL) support
Comprehensive flexPWR® technology
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— Flexible power management architecture
— LVCMOS Variable I/O voltage range: +1.8 V to +3.3 V
— Integrated 1.2 V regulator with disable feature
HP Auto-MDIX support
Small footprint 32-pin SQFN lead-free RoHS
compliant package (5 x 5 x 0.9 mm height)
Deterministic 100 Mb internal loopback latency
(MII Mode)
Set-Top Boxes
Networked Printers and Servers
Test Instrumentation
LAN on Motherboard
Embedded Telecom Applications
Video Record/Playback Systems
Cable Modems/Routers
DSL Modems/Routers
Digital Video Recorders
IP and Video Phones
Wireless Access Points
Digital Televisions
Digital Media Adaptors/Servers
Gaming Consoles
POE Applications (Refer to SMSC Application Note 17.18)
Compliant with IEEE802.3/802.3u (Fast Ethernet)
Compliant with ISO 802-3/IEEE 802.3 (10BASE-T)
Compliant with Energy Efficient Ethernet IEEE 802.3az
Loop-back modes
Auto-negotiation
Automatic polarity detection and correction
Link status change wake-up detection
Vendor specific register functions
Supports both MII and the reduced pin count RMII
interfaces
Power and I/Os
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Target Applications
High-performance 10/100 Ethernet transceiver
Various low power modes
Integrated power-on reset circuit
Two status LED outputs
May be used with a single 3.3 V supply
Additional Features
— Ability to use a low cost 25 MHz crystal for reduced
BOM
Packaging
— 32-pin SQFN (5 x 5 mm) lead-free RoHS compliant
package with MII and RMII
Environmental
— Commercial temperature range (0°C to +70°C)
— Industrial temperature range (-40°C to +85°C)
SMSC LAN8740A/LAN8740Ai
Revision 1.1 (05-10-13)
DATASHEET
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
ORDER NUMBER(S):
LAN8740A-EN (Tray) for 32-pin, SQFN lead-free RoHS compliant package (0°C to +70°C temp)
LAN8740Ai-EN (Tray) for 32-pin, SQFN lead-free RoHS compliant package (-40°C to +85°C temp)
LAN8740A-EN-TR (Tape & Reel) for 32-pin, SQFN lead-free RoHS compliant package (0°C to +70°C temp)
LAN8740Ai-EN-TR (Tape & Reel) for 32-pin, SQFN lead-free RoHS compliant package (-40 to +85°C temp)
This product meets the halogen maximum concentration values per IEC61249-2-21
For RoHS compliance and environmental information, please visit www.smsc.com/rohs
Please contact your SMSC sales representative for additional documentation related to this product
such as application notes, anomaly sheets, and design guidelines.
Copyright © 2013 SMSC or its subsidiaries. All rights reserved.
Circuit diagrams and other information relating to SMSC products are included as a means of illustrating typical applications. Consequently, complete information sufficient for
construction purposes is not necessarily given. Although the information has been checked and is believed to be accurate, no responsibility is assumed for inaccuracies. SMSC
reserves the right to make changes to specifications and product descriptions at any time without notice. Contact your local SMSC sales office to obtain the latest specifications
before placing your product order. The provision of this information does not convey to the purchaser of the described semiconductor devices any licenses under any patent
rights or other intellectual property rights of SMSC or others. All sales are expressly conditional on your agreement to the terms and conditions of the most recently dated
version of SMSC's standard Terms of Sale Agreement dated before the date of your order (the "Terms of Sale Agreement"). The product may contain design defects or errors
known as anomalies which may cause the product's functions to deviate from published specifications. Anomaly sheets are available upon request. SMSC products are not
designed, intended, authorized or warranted for use in any life support or other application where product failure could cause or contribute to personal injury or severe property
damage. Any and all such uses without prior written approval of an Officer of SMSC and further testing and/or modification will be fully at the risk of the customer. Copies of
this document or other SMSC literature, as well as the Terms of Sale Agreement, may be obtained by visiting SMSC’s website at http://www.smsc.com. SMSC is a registered
trademark of Standard Microsystems Corporation (“SMSC”). Product names and company names are the trademarks of their respective holders.
The Microchip name and logo, and the Microchip logo are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries.
SMSC DISCLAIMS AND EXCLUDES ANY AND ALL WARRANTIES, INCLUDING WITHOUT LIMITATION ANY AND ALL IMPLIED WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE, TITLE, AND AGAINST INFRINGEMENT AND THE LIKE, AND ANY AND ALL WARRANTIES ARISING FROM ANY COURSE
OF DEALING OR USAGE OF TRADE. IN NO EVENT SHALL SMSC BE LIABLE FOR ANY DIRECT, INCIDENTAL, INDIRECT, SPECIAL, PUNITIVE, OR CONSEQUENTIAL
DAMAGES; OR FOR LOST DATA, PROFITS, SAVINGS OR REVENUES OF ANY KIND; REGARDLESS OF THE FORM OF ACTION, WHETHER BASED ON CONTRACT;
TORT; NEGLIGENCE OF SMSC OR OTHERS; STRICT LIABILITY; BREACH OF WARRANTY; OR OTHERWISE; WHETHER OR NOT ANY REMEDY OF BUYER IS HELD
TO HAVE FAILED OF ITS ESSENTIAL PURPOSE, AND WHETHER OR NOT SMSC HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
Revision 1.1 (05-10-13)
2
DATASHEET
SMSC LAN8740A/LAN8740Ai
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
Table of Contents
Chapter 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.1
1.2
General Terms and Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Chapter 2 Pin Description and Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.1
2.2
Pin Assignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Buffer Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Chapter 3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
Transceiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1.1
100BASE-TX Transmit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1.2
100BASE-TX Receive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1.3
10BASE-T Transmit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1.4
10BASE-T Receive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Auto-Negotiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2.1
Parallel Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2.2
Restarting Auto-Negotiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2.3
Disabling Auto-Negotiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2.4
Half vs. Full Duplex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
HP Auto-MDIX Support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MAC Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4.1
MII . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4.2
RMII . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4.3
MII vs. RMII Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Serial Management Interface (SMI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Interrupt Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.6.1
Primary Interrupt System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.6.2
Alternate Interrupt System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuration Straps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.7.1
PHYAD[2:0]: PHY Address Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.7.2
MODE[2:0]: Mode Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.7.3
RMIISEL: MII/RMII Mode Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.7.4
REGOFF: Internal +1.2 V Regulator Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.7.5
nINTSEL: nINT/TXER/TXD4 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Miscellaneous Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.8.1
LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.8.2
Variable Voltage I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.8.3
Power-Down Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.8.4
Wake on LAN (WoL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.8.5
Energy Efficient Ethernet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.8.6
Isolate Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.8.7
Resets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.8.8
Carrier Sense . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.8.9
Collision Detect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.8.10 Link Integrity Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.8.11 Cable Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.8.12 Loopback Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Application Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SMSC LAN8740A/LAN8740Ai
3
DATASHEET
21
21
24
27
27
28
30
30
30
30
31
31
32
32
34
35
36
37
38
39
39
40
41
41
42
43
43
47
47
48
54
54
54
55
55
55
56
61
63
Revision 1.1 (05-10-13)
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
3.9.1
3.9.2
3.9.3
3.9.4
3.9.5
Simplified System Level Application Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Supply Diagram (1.2 V Supplied by Internal Regulator). . . . . . . . . . . . . . . . . . . .
Power Supply Diagram (1.2 V Supplied by External Source) . . . . . . . . . . . . . . . . . . . . .
Twisted-Pair Interface Diagram (Single Power Supply). . . . . . . . . . . . . . . . . . . . . . . . . .
Twisted-Pair Interface Diagram (Dual Power Supplies) . . . . . . . . . . . . . . . . . . . . . . . . .
63
64
65
66
67
Chapter 4 Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
4.1
4.2
4.3
Register Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Control and Status Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
4.2.1
Basic Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
4.2.2
Basic Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
4.2.3
PHY Identifier 1 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
4.2.4
PHY Identifier 2 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
4.2.5
Auto Negotiation Advertisement Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
4.2.6
Auto Negotiation Link Partner Ability Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
4.2.7
Auto Negotiation Expansion Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
4.2.8
Auto Negotiation Next Page TX Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
4.2.9
Auto Negotiation Next Page RX Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
4.2.10 MMD Access Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
4.2.11 MMD Access Address/Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
4.2.12 EDPD NLP / Crossover Time / EEE Configuration Register . . . . . . . . . . . . . . . . . . . . . . 82
4.2.13 Mode Control/Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
4.2.14 Special Modes Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
4.2.15 TDR Patterns/Delay Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
4.2.16 TDR Control/Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
4.2.17 Symbol Error Counter Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
4.2.18 Special Control/Status Indications Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
4.2.19 Cable Length Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
4.2.20 Interrupt Source Flag Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
4.2.21 Interrupt Mask Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
4.2.22 PHY Special Control/Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
MDIO Manageable Device (MMD) Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
4.3.1
PCS Control 1 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
4.3.2
PCS Status 1 Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
4.3.3
PCS MMD Devices Present 1 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
4.3.4
PCS MMD Devices Present 2 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
4.3.5
EEE Capability Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
4.3.6
EEE Wake Error Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
4.3.7
Wakeup Control and Status Register (WUCSR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
4.3.8
Wakeup Filter Configuration Register A (WUF_CFGA). . . . . . . . . . . . . . . . . . . . . . . . . 103
4.3.9
Wakeup Filter Configuration Register B (WUF_CFGB). . . . . . . . . . . . . . . . . . . . . . . . . 104
4.3.10 Wakeup Filter Byte Mask Registers (WUF_MASK). . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
4.3.11 MAC Receive Address A Register (RX_ADDRA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
4.3.12 MAC Receive Address B Register (RX_ADDRB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
4.3.13 MAC Receive Address C Register (RX_ADDRC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
4.3.14 Miscellaneous Configuration Register (MCFGR). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
4.3.15 Auto-Negotiation MMD Devices Present 1 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
4.3.16 Auto-Negotiation MMD Devices Present 2 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
4.3.17 EEE Advertisement Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
4.3.18 EEE Link Partner Advertisement Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
4.3.19 Vendor Specific MMD 1 Device ID 1 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
4.3.20 Vendor Specific MMD 1 Device ID 2 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Revision 1.1 (05-10-13)
4
DATASHEET
SMSC LAN8740A/LAN8740Ai
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.3.21
4.3.22
4.3.23
4.3.24
4.3.25
4.3.26
4.3.27
Vendor Specific 1 MMD Devices Present 1 Register . . . . . . . . . . . . . . . . . . . . . . . . . .
Vendor Specific 1 MMD Devices Present 2 Register . . . . . . . . . . . . . . . . . . . . . . . . . .
Vendor Specific MMD 1 Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TDR Match Threshold Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TDR Short/Open Threshold Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vendor Specific MMD 1 package ID 1 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vendor Specific MMD 1 package ID 2 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
117
118
119
120
121
122
123
Chapter 5 Operational Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
5.1
5.2
5.3
5.4
5.5
5.6
5.7
Absolute Maximum Ratings*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating Conditions** . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Package Thermal Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.1
Regulator Disabled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.2
Regulator Enabled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DC Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AC Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.6.1
Equivalent Test Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.6.2
Power-On nRST & Configuration Strap Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.6.3
MII Interface Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.6.4
RMII Interface Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.6.5
SMI Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Clock Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
124
125
125
126
126
126
127
129
129
130
131
134
136
137
Chapter 6 Package Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
Chapter 7 Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
SMSC LAN8740A/LAN8740Ai
5
DATASHEET
Revision 1.1 (05-10-13)
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
List of Figures
Figure 1.1
Figure 1.2
Figure 2.1
Figure 3.1
Figure 3.2
Figure 3.3
Figure 3.4
Figure 3.5
Figure 3.6
Figure 3.7
Figure 3.8
Figure 3.9
Figure 3.10
Figure 3.11
Figure 3.12
Figure 3.13
Figure 3.14
Figure 3.15
Figure 3.16
Figure 3.17
Figure 3.18
Figure 3.19
Figure 3.20
Figure 3.21
Figure 5.1
Figure 5.2
Figure 5.3
Figure 5.4
Figure 5.5
Figure 5.6
Figure 5.7
Figure 6.1
Figure 6.2
Figure 6.3
Figure 6.4
Figure 6.5
System Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Architectural Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
32-SQFN Pin Assignments (TOP VIEW) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
100BASE-TX Transmit Data Path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
100BASE-TX Receive Data Path. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Relationship Between Received Data and Specific MII Signals . . . . . . . . . . . . . . . . . . . . . . 26
Direct Cable Connection vs. Cross-over Cable Connection . . . . . . . . . . . . . . . . . . . . . . . . . 31
MDIO Timing and Frame Structure - READ Cycle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
MDIO Timing and Frame Structure - WRITE Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
LED1/nINT/nPME/REGOFF with Internal Regulator Disabled. . . . . . . . . . . . . . . . . . . . . . . . 43
LED1/nINT/nPME/REGOFF with Internal Regulator Enabled . . . . . . . . . . . . . . . . . . . . . . . . 44
LED2/nINT/nPME with nINTSEL Enabled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
LED2/nINT/nPME with nINTSEL Disabled. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
LED1/REGOFF Polarity Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
LED2/nINTSEL Polarity Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
TDR Usage Flow Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Near-end Loopback Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Far Loopback Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Connector Loopback Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Simplified System Level Application Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Power Supply Diagram (1.2 V Supplied by Internal Regulator) . . . . . . . . . . . . . . . . . . . . . . . 64
Power Supply Diagram (1.2 V Supplied by External Source) . . . . . . . . . . . . . . . . . . . . . . . . 65
Twisted-Pair Interface Diagram (Single Power Supply) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Twisted-Pair Interface Diagram (Dual Power Supplies). . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Output Equivalent Test Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Power-On nRST & Configuration Strap Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
MII Receive Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
MII Transmit Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
100 Mbps Internal Loopback MII Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
RMII Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
SMI Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
32-SQFN Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
Recommended PCB Land Pattern. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Taping Dimensions and Part Orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Reel Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Tape Length and Part Quantity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Revision 1.1 (05-10-13)
6
DATASHEET
SMSC LAN8740A/LAN8740Ai
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
List of Tables
Table 2.1
Table 2.2
Table 2.3
Table 2.4
Table 2.5
Table 2.6
Table 2.7
Table 2.8
Table 2.9
Table 3.1
Table 3.2
Table 3.3
Table 3.4
Table 3.5
Table 3.6
Table 3.7
Table 3.8
Table 3.9
Table 3.10
Table 3.11
Table 3.12
Table 4.1
Table 4.2
Table 4.3
Table 5.1
Table 5.2
Table 5.3
Table 5.4
Table 5.5
Table 5.6
Table 5.7
Table 5.8
Table 5.9
Table 5.10
Table 5.11
Table 5.12
Table 5.13
Table 5.14
Table 5.15
Table 6.1
Table 7.1
MII/RMII Signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
LED Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Serial Management Interface (SMI) Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Ethernet Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Miscellaneous Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Analog Reference Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Power Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
32-SQFN Package Pin Assignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Buffer Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4B/5B Code Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
MII/RMII Signal Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Interrupt Management Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Alternative Interrupt System Management Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Pin Names for Address Bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
MODE[2:0] Bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Pin Names for Mode Bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Wakeup Generation Cases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
TDR Propagation Constants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Typical Measurement Error for Open Cable (+/- Meters). . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Typical Measurement Error for Shorted Cable (+/- Meters) . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Match Case Estimated Cable Length (CBLN) Lookup Table. . . . . . . . . . . . . . . . . . . . . . . . . 60
Register Bit Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
SMI Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
MMD Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Package Thermal Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Current Consumption and Power Dissipation (Reg. Disabled) . . . . . . . . . . . . . . . . . . . . . . 126
Current Consumption and Power Dissipation (Reg. Enabled) . . . . . . . . . . . . . . . . . . . . . . . 126
Non-Variable I/O Buffer Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Variable I/O Buffer Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
100BASE-TX Transceiver Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
10BASE-T Transceiver Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Power-On nRST & Configuration Strap Timing Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
MII Receive Timing Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
MII Transmit Timing Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
100 Mbps Internal Loopback MII Timing Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
RMII Timing Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
RMII CLKIN (REF_CLK) Timing Values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
SMI Timing Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Crystal Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
32-SQFN Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
Customer Revision History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
SMSC LAN8740A/LAN8740Ai
7
DATASHEET
Revision 1.1 (05-10-13)
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
Chapter 1 Introduction
1.1
General Terms and Conventions
The following is a list of the general terms used throughout this document:
BYTE
8 bits
FIFO
First In First Out buffer; often used for elasticity buffer
MAC
Media Access Controller
MII
Media Independent Interface
RMII™
Reduced Media Independent Interface
N/A
Not Applicable
X
Indicates that a logic state is “don’t care” or undefined.
RESERVED Refers to a reserved bit field or address. Unless otherwise noted, reserved bits must always be zero
for write operations. Unless otherwise noted, values are not guaranteed when reading reserved bits.
Unless otherwise noted, do not read or write to reserved addresses.
SMI
1.2
Serial Management Interface
General Description
The LAN8740A/LAN8740Ai is a low-power 10BASE-T/100BASE-TX physical layer (PHY) transceiver
with variable I/O voltage that is compliant with the IEEE 802.3, 802.3u, and 802.3az (Energy Efficient
Ethernet) standards. Energy Efficient Ethernet (EEE) support results in significant power savings during
low link utilizations.
The LAN8740A/LAN8740Ai supports communication with an Ethernet MAC via a standard MII (IEEE
802.3u)/RMII interface. It contains a full-duplex 10-BASE-T/100BASE-TX transceiver and supports
10 Mbps (10BASE-T) and 100 Mbps (100BASE-TX) operation. The LAN8740A/LAN8740Ai implements
auto-negotiation to automatically determine the best possible speed and duplex mode of operation. HP
Auto-MDIX support allows the use of direct connect or cross-over LAN cables. Integrated Wake on LAN
(WoL) support provides a mechanism to trigger an interrupt upon reception of a perfect DA, broadcast,
magic packet, or wakeup frame.
The LAN8740A/LAN8740Ai supports both IEEE 802.3-2005 compliant and vendor-specific register
functions. However, no register access is required for operation. The initial configuration may be
selected via the configuration pins as described in Section 3.7, "Configuration Straps," on page 39.
Register-selectable configuration options may be used to further define the functionality of the
transceiver.
The LAN8740A/LAN8740Ai can be programmed to support wake-on-LAN at the physical layer,
allowing detection of configurable Wake-up Frame and Magic packets. This feature allows filtering of
packets at the PHY layer, without requiring MAC intervention. Additionally, the LAN8740A/LAN8740Ai
supports cable diagnostics which allow the device to identify opens/shorts and their location on the
cable via vendor-specific registers.
Per IEEE 802.3-2005 standards, all digital interface pins are tolerant to 3.6 V. The device can be
configured to operate on a single 3.3 V supply utilizing an integrated 3.3 V to 1.2 V linear regulator.
Revision 1.1 (05-10-13)
8
DATASHEET
SMSC LAN8740A/LAN8740Ai
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
The linear regulator may be optionally disabled, allowing usage of a high efficiency external regulator
for lower system power dissipation.
The LAN8740A/LAN8740Ai is available in commercial (0°C to +70°C) and industrial (-40°C to +85°C)
temperature range versions. A typical system application is shown in Figure 1.1. Figure 1.2 provides
an internal block diagram of the device.
10/100
Ethernet
MAC
MII/
RMII
LAN8740A/
LAN8740Ai
Mode
MDI
Transformer
RJ45
LED
Crystal or
Clock
Oscillator
Figure 1.1 System Block Diagram
MODE[0:2]
nRST
Mode Control
Reset Control
AutoNegotiation
100M TX
Logic
100M
Transmitter
HP Auto-MDIX
RXP/RXN
Transmitter
RMIISEL
TXD[0:3]
SMI
TXEN
Management
Control
10M TX
Logic
10M
Transmitter
TXP/TXN
MDIX
Control
TXER
XTAL1/CLKIN
TXCLK
RXDV
RXER
RXCLK
CRS
RMII/MII Logic
RXD[0:3]
PLL
100M RX
Logic
DSP System:
Clock
Data Recovery
Equalizer
WoL
Analog-toDigital
100M PLL
Receiver
10M RX
Logic
COL/CRS_DV
MDC
Squeltch
& Filters
10M PLL
MDIO
Interrupt
Generator
nINT
LED1
LEDs
Central Bias
PHY Address
Latches
LAN8740A/LAN8740Ai
XTAL2
LED2
RBIAS
PHYAD[0:2]
Figure 1.2 Architectural Overview
SMSC LAN8740A/LAN8740Ai
9
DATASHEET
Revision 1.1 (05-10-13)
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
TXD2
TXD1
TXD0
TXEN
TXCLK
nRST
nINT/TXER/TXD4
MDC
24
23
22
21
20
19
18
17
Chapter 2 Pin Description and Configuration
TXD3
25
16
MDIO
RXDV
26
15
COL/CRS_DV/MODE2
VDD1A
27
14
CRS
TXN
28
13
RXER/RXD4/PHYAD0
TXP
29
12
VDDIO
RXN
30
11
RXD0/MODE0
RXP
31
10
RXD1/MODE1
RBIAS
32
9
RXD2/nPME/RMIISEL
LAN8740A/
LAN8740Ai
6
7
8
RXCLK/PHYAD1
RXD3/PHYAD2
4
XTAL2
VDDCR
3
LED1/nINT/nPME/REGOFF
5
2
LED2/nINT/nPME/nINTSEL
XTAL1/CLKIN
1
VDD2A
e3
Note: Exposed pad (VSS) on bottom of package must be connected to ground.
Figure 2.1 32-SQFN Pin Assignments (TOP VIEW)
Note: When a lower case “n” is used at the beginning of the signal name, it indicates that the signal
is active low. For example, nRST indicates that the reset signal is active low.
Note: The buffer type for each signal is indicated in the BUFFER TYPE column. A description of the
buffer types is provided in Section 2.2.
Revision 1.1 (05-10-13)
10
DATASHEET
SMSC LAN8740A/LAN8740Ai
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
Table 2.1 MII/RMII Signals
NUM PINS
NAME
SYMBOL
BUFFER
TYPE
1
Transmit
Data 0
TXD0
VIS
The MAC transmits data to the transceiver using
this signal in all modes.
1
Transmit
Data 1
TXD1
VIS
The MAC transmits data to the transceiver using
this signal in all modes.
TXD2
VIS
1
Transmit
Data 2
(MII Mode)
The MAC transmits data to the transceiver using
this signal in MII mode.
TXD3
1
Transmit
Data 3
(MII Mode)
Interrupt
Output
nINT
DESCRIPTION
Note:
VIS
The MAC transmits data to the transceiver using
this signal in MII mode.
Note:
VOD8
(PU)
TXER
VIS
Note:
The nINT signal can be optionally
configured to output on the LED1 or
LED2 pins. Refer to Section 3.6,
"Interrupt Management," on page 36 for
additional details on device interrupts.
Note:
Refer to Section 3.8.1.6, "nINTSEL and
LED2 Polarity Selection," on page 47 for
details on how the nINTSEL
configuration strap is used to determine
the function of this pin.
When driven high, the 4B/5B encode process
substitutes the Transmit Error code-group (/H/)
for the encoded data word. This input is ignored
in the 10BASE-T mode of operation. This signal
is also used in EEE mode as TXER when
TXEN = 1, and as LPI when TXEN = 0.
Note:
Transmit
Data 4
(MII Mode)
TXD4
VIS
(PU)
This signal must be grounded in RMII
mode.
Active low interrupt output. Place an external
resistor pull-up to VDDIO.
1
Transmit
Error
(MII Mode)
This signal must be grounded in RMII
mode.
This signal is not used in RMII mode.
In Symbol Interface (5B decoding) mode, this
signal becomes the MII Transmit Data 4 line (the
MSB of the 5-bit symbol code-group).
Note:
This signal is not used in RMII mode.
1
Transmit
Enable
TXEN
VIS
(PD)
Indicates that valid transmission data is present
on TXD[3:0]. In RMII mode, only TXD[1:0]
provide valid data.
TXCLK
VO8
1
Transmit
Clock
(MII Mode)
Used to latch data from the MAC into the
transceiver.
MII (100BASE-TX): 25 MHz
MII (10BASE-T): 2.5 MHz
Note:
SMSC LAN8740A/LAN8740Ai
11
DATASHEET
This signal is not used in RMII mode.
Revision 1.1 (05-10-13)
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
Table 2.1 MII/RMII Signals (continued)
NUM PINS
1
1
NAME
SYMBOL
BUFFER
TYPE
Receive
Data 0
RXD0
VO8
Bit 0 of the 4 (2 in RMII mode) data bits that are
sent by the transceiver on the receive path.
PHY
Operating
Mode 0
Configuration
Strap
MODE0
VIS
(PU)
Combined with MODE1 and MODE2, this
configuration strap sets the default PHY mode.
Receive
Data 1
RXD1
VO8
Bit 1 of the 4 (2 in RMII mode) data bits that are
sent by the transceiver on the receive path.
PHY
Operating
Mode 1
Configuration
Strap
MODE1
VIS
(PU)
Combined with MODE0 and MODE2, this
configuration strap sets the default PHY mode.
Receive
Data 2
(MII Mode)
RXD2
Power
Management
Event Output
nPME
DESCRIPTION
See Note 2.1 for more information on
configuration straps.
Note:
See Note 2.1 for more information on
configuration straps.
Note:
VO8
Note:
VO8
VIS
(PD)
This signal is not used in RMII mode.
When in RMII mode, this pin may be used
alternatively as an active low Power Management
Event (PME) output.
1
RMIISEL
Refer to Section 3.7.2, "MODE[2:0]:
Mode Configuration," on page 40 for
additional details.
Bit 2 of the 4 (in MII mode) data bits that are sent
by the transceiver on the receive path.
Note:
MII/RMII
Mode Select
Configuration
Strap
Refer to Section 3.7.2, "MODE[2:0]:
Mode Configuration," on page 40 for
additional details.
The nPME signal can be optionally
configured to output on the LED1,
LED2, or RXD2/nPME/nINTSEL pins.
Refer to Section 3.8.4, "Wake on LAN
(WoL)," on page 48 for additional nPME
and WoL information.
This configuration strap selects the MII or RMII
mode of operation. When strapped low to VSS,
MII mode is selected. When strapped high to
VDDIO RMII mode is selected.
See Note 2.1 for more information on
configuration straps.
Note:
Revision 1.1 (05-10-13)
12
DATASHEET
Refer to Section 3.7.3, "RMIISEL:
MII/RMII Mode Configuration," on
page 41 for additional details.
SMSC LAN8740A/LAN8740Ai
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
Table 2.1 MII/RMII Signals (continued)
NUM PINS
1
NAME
SYMBOL
BUFFER
TYPE
Receive
Data 3
(MII Mode)
RXD3
VO8
PHY Address
2
Configuration
Strap
PHYAD2
DESCRIPTION
Bit 3 of the 4 (in MII mode) data bits that are sent
by the transceiver on the receive path.
Note:
VIS
(PD)
Combined with PHYAD0 and PHYAD1, this
configuration strap sets the transceiver’s SMI
address.
See Note 2.1 for more information on
configuration straps.
Note:
Receive Error
RXER
VO8
RXD4
VO8
Note:
PHYAD0
VIS
(PD)
See Note 2.1 for more information on
configuration straps.
Refer to Section 3.7.1, "PHYAD[2:0]:
PHY Address Configuration," on
page 39 for additional information.
Receive
Clock
(MII Mode)
RXCLK
VO8
In MII mode, this pin is the receive clock output.
MII (100BASE-TX): 25 MHz
MII (10BASE-T): 2.5 MHz
PHY Address
1
Configuration
Strap
PHYAD1
VIS
(PD)
Combined with PHYAD0 and PHYAD2, this
configuration strap sets the transceiver’s SMI
address.
See Note 2.1 for more information on
configuration straps.
Note:
1
Unless configured to the Symbol
Interface mode, this pin functions as
RXER.
Combined with PHYAD1 and PHYAD2, this
configuration strap sets the transceiver’s SMI
address.
Note:
1
This signal is optional in RMII mode.
In Symbol Interface (5B decoding) mode, this
signal is the MII Receive Data 4 signal, the MSB
of the received 5-bit symbol code-group.
1
PHY Address
0
Configuration
Strap
Refer to Section 3.7.1, "PHYAD[2:0]:
PHY Address Configuration," on
page 39 for additional information.
This signal is asserted to indicate that an error
was detected somewhere in the frame presently
being transferred from the transceiver. This signal
is also used in EEE mode as RXER when
RXDV = 1, and as LPI when RXDV = 0.
Note:
Receive
Data 4
(MII Mode)
This signal is not used in RMII mode.
Receive Data
Valid
SMSC LAN8740A/LAN8740Ai
RXDV
VO8
Refer to Section 3.7.1, "PHYAD[2:0]:
PHY Address Configuration," on
page 39 for additional information.
Indicates that recovered and decoded data is
available on the RXD pins.
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
Table 2.1 MII/RMII Signals (continued)
NUM PINS
NAME
SYMBOL
BUFFER
TYPE
Collision
Detect
(MII Mode)
COL
VO8
This signal is asserted to indicate detection of a
collision condition in MII mode.
Carrier Sense
/ Receive
Data Valid
(RMII Mode)
CRS_DV
VO8
This signal is asserted to indicate the receive
medium is non-idle in RMII mode. When a
10BASE-T packet is received, CRS_DV is
asserted, but RXD[1:0] is held low until the SFD
byte (10101011) is received.
DESCRIPTION
Note:
1
1
PHY
Operating
Mode 2
Configuration
Strap
MODE2
Carrier Sense
(MII Mode)
CRS
Note 2.1
Revision 1.1 (05-10-13)
VIS
(PU)
Per the RMII standard, transmitted data
is not looped back onto the receive data
pins in 10BASE-T half-duplex mode.
Combined with MODE0 and MODE1, this
configuration strap sets the default PHY mode.
See Note 2.1 for more information on
configuration straps.
Note:
VO8
(PD)
Refer to Section 3.7.2, "MODE[2:0]:
Mode Configuration," on page 40 for
additional details.
This signal indicates detection of a carrier in MII
mode.
Configuration strap values are latched on power-on reset and system reset. Configuration
straps are identified by an underlined symbol name. Signals that function as configuration
straps must be augmented with an external resistor when connected to a load. Refer to
Section 3.7, "Configuration Straps," on page 39 for additional information.
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SMSC LAN8740A/LAN8740Ai
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
Table 2.2 LED Pins
NUM PINS
NAME
SYMBOL
BUFFER
TYPE
LED 1
LED1
O12
DESCRIPTION
This pin can be used to indicate link activity, link
speed, nINT, or nPME as configured via the
LED1 Function Select field of the Wakeup Control
and Status Register (WUCSR).
Note:
Interrupt
Output
nINT
Power
Management
Event Output
nPME
Regulator Off
Configuration
Strap
REGOFF
O12
Active low interrupt output.
Note:
O12
By default, the nINT signal is output on
the nINT/TXER/TXD4 pin. The nINT
signal can be optionally configured to
output on the LED1 or LED2 pins. Refer
to Section 3.6, "Interrupt Management,"
on page 36 for additional details on
device interrupts.
Active low Power Management Event (PME)
output.
Note:
1
IS
(PD)
Refer to Section 3.8.1, "LEDs," on
page 43 and Section 3.8.4, "Wake on
LAN (WoL)," on page 48 for additional
LED information.
The nPME signal can be optionally
configured to output on the LED1,
LED2, or RXD2/nPME/nINTSEL pins.
Refer to Section 3.8.4, "Wake on LAN
(WoL)," on page 48 for additional nPME
and WoL information.
This configuration strap is used to disable the
internal 1.2 V regulator. When the regulator is
disabled, external 1.2 V must be supplied to
VDDCR.
When REGOFF is pulled high to VDD2A with
an external resistor, the internal regulator is
disabled.
When REGOFF is floating or pulled low, the
internal regulator is enabled (default).
See Note 2.2 for more information on
configuration straps.
Note:
SMSC LAN8740A/LAN8740Ai
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DATASHEET
Refer to Section 3.7.4, "REGOFF:
Internal +1.2 V Regulator
Configuration," on page 41 for additional
details.
Revision 1.1 (05-10-13)
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
Table 2.2 LED Pins (continued)
NUM PINS
NAME
SYMBOL
BUFFER
TYPE
LED 2
LED2
O12
DESCRIPTION
This pin can be used to indicate link activity, link
speed, nINT, or nPME as configured via the
LED2 Function Select field of the Wakeup Control
and Status Register (WUCSR).
Note:
1
Interrupt
Output
nINT
Power
Management
Event Output
nPME
nINT/TXER/
TXD4
Function
Select
Configuration
Strap
nINTSEL
O12
Active low interrupt output.
Note:
O12
By default, the nINT signal is output on
the nINT/TXER/TXD4 pin. The nINT
signal can be optionally configured to
output on the LED1 or LED2 pins. Refer
to Section 3.6, "Interrupt Management,"
on page 36 for additional details on
device interrupts.
Active low Power Management Event (PME)
output.
Note:
IS
(PU)
Refer to Section 3.8.1, "LEDs," on
page 43 and Section 3.8.4, "Wake on
LAN (WoL)," on page 48 for additional
LED information.
The nPME signal can be optionally
configured to output on the LED1,
LED2, or RXD2/nPME/nINTSEL pins.
Refer to Section 3.8.4, "Wake on LAN
(WoL)," on page 48 for additional nPME
and WoL information.
This configuration strap selects the mode of the
nINT/TXER/TXD4 pin.
When nINTSEL is floated or pulled to VDD2A,
nINT is selected for operation on the
nINT/TXER/TXD4 pin (default).
When nINTSEL is pulled low to VSS,
TXER/TXD4 is selected for operation on the
nINT/TXER/TXD4 pin.
See Note 2.2 for more information on
configuration straps.
Note:
Note 2.2
Revision 1.1 (05-10-13)
Refer to See Section 3.8.1.6, "nINTSEL
and LED2 Polarity Selection," on
page 47 for additional information.
Configuration strap values are latched on power-on reset and system reset. Configuration
straps are identified by an underlined symbol name. Signals that function as configuration
straps must be augmented with an external resistor when connected to a load. Refer to
Section 3.7, "Configuration Straps," on page 39 for additional information.
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SMSC LAN8740A/LAN8740Ai
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
Table 2.3 Serial Management Interface (SMI) Pins
BUFFER
TYPE
NUM PINS
NAME
SYMBOL
DESCRIPTION
1
SMI Data
Input/Output
MDIO
VIS/
VO8
(PU)
Serial Management Interface data input/output
1
SMI Clock
MDC
VIS
Serial Management Interface clock
Table 2.4 Ethernet Pins
NUM PINS
NAME
SYMBOL
BUFFER
TYPE
Ethernet
TX/RX
Positive
Channel 1
TXP
AIO
Transmit/Receive Positive Channel 1
1
TXN
AIO
Transmit/Receive Negative Channel 1
1
Ethernet
TX/RX
Negative
Channel 1
RXP
AIO
Transmit/Receive Positive Channel 2
1
Ethernet
TX/RX
Positive
Channel 2
RXN
AIO
Transmit/Receive Negative Channel 2
1
Ethernet
TX/RX
Negative
Channel 2
DESCRIPTION
Table 2.5 Miscellaneous Pins
NAME
SYMBOL
BUFFER
TYPE
External
Crystal
Input
XTAL1
ICLK
External crystal input
External
Clock Input
CLKIN
ICLK
Single-ended clock oscillator input.
1
External
Crystal
Output
XTAL2
OCLK
1
External
Reset
nRST
VIS
(PU)
NUM PINS
1
SMSC LAN8740A/LAN8740Ai
DESCRIPTION
Note:
When using a single ended clock
oscillator, XTAL2 should be left
unconnected.
External crystal output
System reset. This signal is active low.
17
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Datasheet
Table 2.6 Analog Reference Pins
NUM PINS
NAME
SYMBOL
BUFFER
TYPE
External 1%
Bias Resistor
Input
RBIAS
AI
DESCRIPTION
This pin requires connection of a 12.1 kΩ (1%)
resistor to ground.
Refer to the LAN8740A/LAN8740Ai reference
schematic for connection information.
1
Note:
The nominal voltage is 1.2 V and the
resistor will dissipate approximately
1 mW of power.
Table 2.7 Power Pins
NUM PINS
NAME
SYMBOL
BUFFER
TYPE
+1.8 V to
+3.3 V
Variable I/O
Power
VDDIO
P
1
+1.2 V Digital
Core Power
Supply
VDDCR
DESCRIPTION
+1.8 V to +3.3 V variable I/O power.
Refer to the LAN8740A/LAN8740Ai reference
schematic for connection information.
P
Supplied by the on-chip regulator unless
configured for regulator off mode via the
REGOFF configuration strap.
Refer to the LAN8740A/LAN8740Ai reference
schematic for connection information.
1
Note:
VDD1A
1
+3.3 V
Channel 1
Analog Port
Power
VDD2A
1
+3.3 V
Channel 2
Analog Port
Power
1
Ground
VSS
Revision 1.1 (05-10-13)
P
1 µF and 470 pF decoupling capacitors
in parallel to ground should be used on
this pin.
+3.3 V Analog Port Power to Channel 1.
Refer to the LAN8740A/LAN8740Ai reference
schematic for connection information.
P
+3.3 V Analog Port Power to Channel 2 and the
internal regulator.
Refer to the LAN8740A/LAN8740Ai reference
schematic for connection information.
P
Common ground. This exposed pad must be
connected to the ground plane with a via array.
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SMSC LAN8740A/LAN8740Ai
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
2.1
Pin Assignments
Table 2.8 32-SQFN Package Pin Assignments
PIN NUM
PIN NAME
PIN NUM
PIN NAME
1
VDD2A
17
MDC
2
LED2/nINT/nPME/nINTSEL
18
nINT/TXER/TXD4
3
LED1/nINT/nPME/REGOFF
19
nRST
4
XTAL2
20
TXCLK
5
XTAL1/CLKIN
21
TXEN
6
VDDCR
22
TXD0
7
RXCLK/PHYAD1
23
TXD1
8
RXD3/PHYAD2
24
TXD2
9
RXD2/nPME/RMIISEL
25
TXD3
10
RXD1/MODE1
26
RXDV
11
RXD0/MODE0
27
VDD1A
12
VDDIO
28
TXN
13
RXER/RXD4/PHYAD0
29
TXP
14
CRS
30
RXN
15
COL/CRS_DV/MODE2
31
RXP
16
MDIO
32
RBIAS
SMSC LAN8740A/LAN8740Ai
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DATASHEET
Revision 1.1 (05-10-13)
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
2.2
Buffer Types
Table 2.9 Buffer Types
BUFFER TYPE
IS
DESCRIPTION
Schmitt-triggered input
O12
Output with 12 mA sink and 12 mA source
VIS
Variable voltage Schmitt-triggered input
VO8
Variable voltage output with 8 mA sink and 8 mA source
VOD8
PU
Variable voltage open-drain output with 8 mA sink
50 µA (typical) internal pull-up. Unless otherwise noted in the pin description, internal pullups are always enabled.
Note:
PD
Internal pull-up resistors prevent unconnected inputs from floating. Do not rely on
internal resistors to drive signals external to the device. When connected to a load
that must be pulled high, an external resistor must be added.
50 µA (typical) internal pull-down. Unless otherwise noted in the pin description, internal
pull-downs are always enabled.
Note:
AI
Internal pull-down resistors prevent unconnected inputs from floating. Do not rely
on internal resistors to drive signals external to the device. When connected to a
load that must be pulled low, an external resistor must be added.
Analog input
AIO
Analog bi-directional
ICLK
Crystal oscillator input pin
OCLK
Crystal oscillator output pin
P
Power pin
Note: The digital signals are not 5 V tolerant. Refer to Section 5.1, "Absolute Maximum Ratings*," on
page 124 for additional buffer information.
Note: Sink and source capabilities are dependant on the VDDIO voltage. Refer to Section 5.1,
"Absolute Maximum Ratings*," on page 124 for additional information.
Revision 1.1 (05-10-13)
20
DATASHEET
SMSC LAN8740A/LAN8740Ai
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
Chapter 3 Functional Description
This chapter provides functional descriptions of the various device features. These features have been
categorized into the following sections:
Transceiver
Auto-Negotiation
HP Auto-MDIX Support
MAC Interface
Serial Management Interface (SMI)
Interrupt Management
Configuration Straps
Miscellaneous Functions
Application Diagrams
3.1
Transceiver
3.1.1
100BASE-TX Transmit
The 100BASE-TX transmit data path is shown in Figure 3.1. Each major block is explained in the
following subsections.
TX_CLK
(for MII only)
MAC
PLL
Ext Ref_CLK (for RMII only)
MII 25 MHz by 4 bits
or
RMII 50 MHz by 2 bits
125 Mbps Serial
MII/RMII
25 MHz
by 4 bits
4B/5B
Encoder
NRZI
Converter
NRZI
MLT-3
Converter
MLT-3
MLT-3
Magnetics
MLT-3
RJ45
25 MHz by
5 bits
Scrambler
and PISO
Tx
Driver
MLT-3
CAT-5
Figure 3.1 100BASE-TX Transmit Data Path
SMSC LAN8740A/LAN8740Ai
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
3.1.1.1
100BASE-TX Transmit Data Across the MII/RMII Interface
For MII, the MAC controller drives the transmit data onto the TXD bus and asserts TXEN to indicate
valid data. The data is latched by the transceiver’s MII block on the rising edge of TXCLK. The data
is in the form of 4-bit wide 25 MHz data.
For RMII, the MAC controller drives the transmit data onto the TXD bus and asserts TXEN to indicate
valid data. The data is latched by the transceiver’s RMII block on the rising edge of REF_CLK. The
data is in the form of 2-bit wide 50 MHz data.
3.1.1.2
4B/5B Encoding
The transmit data passes from the MII/RMII block to the 4B/5B encoder. This block encodes the data
from 4-bit nibbles to 5-bit symbols (known as “code-groups”) according to Table 3.1. Each 4-bit datanibble is mapped to 16 of the 32 possible code-groups. The remaining 16 code-groups are either used
for control information or are not valid.
The first 16 code-groups are referred to by the hexadecimal values of their corresponding data nibbles,
0 through F. The remaining code-groups are given letter designations with slashes on either side. For
example, an IDLE code-group is /I/, a transmit error code-group is /H/, etc.
Table 3.1 4B/5B Code Table
CODE
GROUP
SYM
RECEIVER
INTERPRETATION
11110
0
0
0000
01001
1
1
10100
2
10101
TRANSMITTER
INTERPRETATION
0
0000
0001
1
0001
2
0010
2
0010
3
3
0011
3
0011
01010
4
4
0100
4
0100
01011
5
5
0101
5
0101
01110
6
6
0110
6
0110
01111
7
7
0111
7
0111
10010
8
8
1000
8
1000
10011
9
9
1001
9
1001
10110
A
A
1010
A
1010
10111
B
B
1011
B
1011
11010
C
C
1100
C
1100
11011
D
D
1101
D
1101
11100
E
E
1110
E
1110
11101
F
F
1111
F
1111
11111
I
IDLE
Sent after /T/R until TXEN
11000
J
First nibble of SSD, translated to “0101”
following IDLE, else RXER
Sent for rising TXEN
Revision 1.1 (05-10-13)
DATA
22
DATASHEET
DATA
SMSC LAN8740A/LAN8740Ai
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
Table 3.1 4B/5B Code Table (continued)
CODE
GROUP
SYM
10001
K
Second nibble of SSD, translated to
“0101” following J, else RXER
Sent for rising TXEN
01101
T
First nibble of ESD, causes de-assertion
of CRS if followed by /R/, else assertion
of RXER
Sent for falling TXEN
00111
R
Second nibble of ESD, causes
deassertion of CRS if following /T/, else
assertion of RXER
Sent for falling TXEN
00100
H
Transmit Error Symbol
Sent for rising TXER
00110
V
INVALID, RXER if during RXDV
INVALID
11001
V
INVALID, RXER if during RXDV
INVALID
00000
V
Indicates to receiver that the transmitter
will be going to LPI
Sent due to LPI. Used to tell receiver
before transmitter goes to LPI. Also used
for refresh cycles during LPI.
00001
V
INVALID, RXER if during RXDV
INVALID
00010
V
INVALID, RXER if during RXDV
INVALID
00011
V
INVALID, RXER if during RXDV
INVALID
00101
V
INVALID, RXER if during RXDV
INVALID
01000
V
INVALID, RXER if during RXDV
INVALID
01100
V
INVALID, RXER if during RXDV
INVALID
10000
V
INVALID, RXER if during RXDV
INVALID
3.1.1.3
RECEIVER
INTERPRETATION
TRANSMITTER
INTERPRETATION
Scrambling
Repeated data patterns (especially the IDLE code-group) can have power spectral densities with large
narrow-band peaks. Scrambling the data helps eliminate these peaks and spread the signal power
more uniformly over the entire channel bandwidth. This uniform spectral density is required by FCC
regulations to prevent excessive EMI from being radiated by the physical wiring.
The seed for the scrambler is generated from the transceiver address, PHYAD, ensuring that in
multiple-transceiver applications, such as repeaters or switches, each transceiver will have its own
scrambler sequence.
The scrambler also performs the Parallel In Serial Out conversion (PISO) of the data.
3.1.1.4
NRZI and MLT-3 Encoding
The scrambler block passes the 5-bit wide parallel data to the NRZI converter where it becomes a
serial 125 MHz NRZI data stream. The NRZI is encoded to MLT-3. MLT-3 is a tri-level code where a
change in the logic level represents a code bit “1” and the logic output remaining at the same level
represents a code bit “0”.
SMSC LAN8740A/LAN8740Ai
23
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3.1.1.5
100M Transmit Driver
The MLT3 data is then passed to the analog transmitter, which drives the differential MLT-3 signal, on
outputs TXP and TXN, to the twisted pair media across a 1:1 ratio isolation transformer. The 10BASET and 100BASE-TX signals pass through the same transformer so that common “magnetics” can be
used for both. The transmitter drives into the 100 Ω impedance of the CAT-5 cable. Cable termination
and impedance matching require external components.
3.1.1.6
100M Phase Lock Loop (PLL)
The 100M PLL locks onto reference clock and generates the 125 MHz clock used to drive the 125 MHz
logic and the 100BASE-TX transmitter.
3.1.2
100BASE-TX Receive
The 100BASE-TX receive data path is shown in Figure 3.2. Each major block is explained in the
following subsections.
RX_CLK
(for MII only)
MAC
PLL
Ext Ref_CLK (for RMII only)
MII 25 MHz by 4 bits
or
RMII 50 MHz by 2 bits
25 MHz
by 4 bits
MII/RMII
25 MHz by
5 bits
4B/5B
Decoder
Descrambler
and SIPO
125 Mbps Serial
NRZI
Converter
A/D
Converter
NRZI
MLT-3
MLT-3
Converter
Magnetics
MLT-3
MLT-3
RJ45
DSP: Timing
recovery, Equalizer
and BLW Correction
MLT-3
CAT-5
6 bit Data
Figure 3.2 100BASE-TX Receive Data Path
3.1.2.1
100M Receive Input
The MLT-3 from the cable is fed into the transceiver (on inputs RXP and RXN) via a 1:1 ratio
transformer. The ADC samples the incoming differential signal at a rate of 125M samples per second.
Using a 64-level quanitizer, it generates 6 digital bits to represent each sample. The DSP adjusts the
gain of the ADC according to the observed signal levels such that the full dynamic range of the ADC
can be used.
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3.1.2.2
Equalizer, Baseline Wander Correction and Clock and Data Recovery
The 6 bits from the ADC are fed into the DSP block. The equalizer in the DSP section compensates
for phase and amplitude distortion caused by the physical channel consisting of magnetics, connectors,
and CAT- 5 cable. The equalizer can restore the signal for any good-quality CAT-5 cable between 1 m
and 100 m.
If the DC content of the signal is such that the low-frequency components fall below the low frequency
pole of the isolation transformer, then the droop characteristics of the transformer will become
significant and Baseline Wander (BLW) on the received signal will result. To prevent corruption of the
received data, the transceiver corrects for BLW and can receive the ANSI X3.263-1995 FDDI TP-PMD
defined “killer packet” with no bit errors.
The 100M PLL generates multiple phases of the 125 MHz clock. A multiplexer, controlled by the timing
unit of the DSP, selects the optimum phase for sampling the data. This is used as the received
recovered clock. This clock is used to extract the serial data from the received signal.
3.1.2.3
NRZI and MLT-3 Decoding
The DSP generates the MLT-3 recovered levels that are fed to the MLT-3 converter. The MLT-3 is then
converted to an NRZI data stream.
3.1.2.4
Descrambling
The descrambler performs an inverse function to the scrambler in the transmitter and also performs
the Serial In Parallel Out (SIPO) conversion of the data.
During reception of IDLE (/I/) symbols. the descrambler synchronizes its descrambler key to the
incoming stream. Once synchronization is achieved, the descrambler locks on this key and is able to
descramble incoming data.
Special logic in the descrambler ensures synchronization with the remote transceiver by searching for
IDLE symbols within a window of 4000 bytes (40 µs). This window ensures that a maximum packet
size of 1514 bytes, allowed by the IEEE 802.3 standard, can be received with no interference. If no
IDLE-symbols are detected within this time-period, receive operation is aborted and the descrambler
re-starts the synchronization process.
3.1.2.5
Alignment
The de-scrambled signal is then aligned into 5-bit code-groups by recognizing the /J/K/ Start-of-Stream
Delimiter (SSD) pair at the start of a packet. Once the code-word alignment is determined, it is stored
and utilized until the next start of frame.
3.1.2.6
5B/4B Decoding
The 5-bit code-groups are translated into 4-bit data nibbles according to the 4B/5B table. The
translated data is presented on the RXD[3:0] signal lines. The SSD, /J/K/, is translated to “0101 0101”
as the first 2 nibbles of the MAC preamble. Reception of the SSD causes the transceiver to assert the
receive data valid signal, indicating that valid data is available on the RXD bus. Successive valid codegroups are translated to data nibbles. Reception of either the End of Stream Delimiter (ESD) consisting
of the /T/R/ symbols, or at least two /I/ symbols causes the transceiver to de-assert the carrier sense
and receive data valid signals.
Note: These symbols are not translated into data.
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3.1.2.7
Receive Data Valid Signal
The Receive Data Valid signal (RXDV) indicates that recovered and decoded nibbles are being
presented on the RXD[3:0] outputs synchronous to RXCLK. RXDV becomes active after the /J/K/
delimiter has been recognized and RXD is aligned to nibble boundaries. It remains active until either
the /T/R/ delimiter is recognized or link test indicates failure or SIGDET becomes false.
RXDV is asserted when the first nibble of translated /J/K/ is ready for transfer over the Media
Independent Interface (MII mode).
CLEAR-TEXT
J
K
5
5
5
D
data
data
data
data
T
R
5
5
5
5
5
D
data
data
data
data
Idle
RX_CLK
RX_DV
RXD
Figure 3.3 Relationship Between Received Data and Specific MII Signals
3.1.2.8
Receiver Errors
During a frame, unexpected code-groups are considered receive errors. Expected code groups are the
DATA set (0 through F), and the /T/R/ (ESD) symbol pair. When a receive error occurs, the RXER
signal is asserted and arbitrary data is driven onto the RXD[3:0] lines. Should an error be detected
during the time that the /J/K/ delimiter is being decoded (bad SSD error), RXER is asserted true and
the value ‘1110’ is driven onto the RXD[3:0] lines. Note that the Valid Data signal is not yet asserted
when the bad SSD error occurs.
3.1.2.9
100M Receive Data Across the MII/RMII Interface
In MII mode, the 4-bit data nibbles are sent to the MII block. These data nibbles are clocked to the
controller at a rate of 25 MHz. The controller samples the data on the rising edge of RXCLK. To ensure
that the setup and hold requirements are met, the nibbles are clocked out of the transceiver on the
falling edge of RXCLK. RXCLK is the 25 MHz output clock for the MII bus. It is recovered from the
received data to clock the RXD bus. If there is no received signal, it is derived from the system
reference clock (XTAL1/CLKIN).
When tracking the received data, RXCLK has a maximum jitter of 0.8 ns (provided that the jitter of the
input clock, XTAL1/CLKIN, is below 100 ps).
In RMII mode, the 2-bit data nibbles are sent to the RMII block. These data nibbles are clocked to the
controller at a rate of 50 MHz. The controller samples the data on the rising edge of XTAL1/CLKIN
(REF_CLK). To ensure that the setup and hold requirements are met, the nibbles are clocked out of
the transceiver on the falling edge of XTAL1/CLKIN (REF_CLK).
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3.1.3
10BASE-T Transmit
Data to be transmitted comes from the MAC layer controller. The 10BASE-T transmitter receives 4-bit
nibbles from the MII at a rate of 2.5 MHz and converts them to a 10 Mbps serial data stream. The
data stream is then Manchester-encoded and sent to the analog transmitter, which drives a signal onto
the twisted pair via the external magnetics.
The 10M transmitter uses the following blocks:
3.1.3.1
MII (digital)
TX 10M (digital)
10M Transmitter (analog)
10M PLL (analog)
10M Transmit Data Across the MII/RMII Interface
The MAC controller drives the transmit data onto the TXD bus. For MII, when the controller has driven
TXEN high to indicate valid data, the data is latched by the MII block on the rising edge of TXCLK.
The data is in the form of 4-bit wide 2.5 MHz data. For RMII, TXD[1:0] shall transition synchronously
with respect to REF_CLK. When TXEN is asserted, TXD[1:0] are accepted for transmission by the
device. TXD[1:0] shall be “00” to indicate idle when TXEN is deasserted. Values of TXD[1:0] other than
“00” when TXEN is deasserted are reserved for out-of-band signalling (to be defined). Values other
than “00” on TXD[1:0] while TXEN is deasserted shall be ignored by the device.TXD[1:0] shall provide
valid data for each REF_CLK period while TXEN is asserted.
In order to comply with legacy 10BASE-T MAC/Controllers, in half-duplex mode the transceiver loops
back the transmitted data, on the receive path. This does not confuse the MAC/Controller since the
COL signal is not asserted during this time. The transceiver also supports the SQE (Heartbeat) signal.
See Section 3.8.9, "Collision Detect," on page 55, for more details.
3.1.3.2
Manchester Encoding
The 4-bit wide data is sent to the 10M TX block. The nibbles are converted to a 10 Mbps serial NRZI
data stream. The 10M PLL locks onto the external clock or internal oscillator and produces a 20 MHz
clock. This is used to Manchester encode the NRZ data stream. When no data is being transmitted
(TXEN is low), the 10M TX block outputs Normal Link Pulses (NLPs) to maintain communications with
the remote link partner.
3.1.3.3
10M Transmit Drivers
The Manchester-encoded data is sent to the analog transmitter where it is shaped and filtered before
being driven out as a differential signal across the TXP and TXN outputs.
3.1.4
10BASE-T Receive
The 10BASE-T receiver gets the Manchester- encoded analog signal from the cable via the magnetics.
It recovers the receive clock from the signal and uses this clock to recover the NRZI data stream. This
10M serial data is converted to 4-bit data nibbles which are passed to the controller via MII at a rate
of 2.5 MHz.
This 10M receiver uses the following blocks:
Filter and SQUELCH (analog)
10M PLL (analog)
RX 10M (digital)
MII (digital)
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3.1.4.1
10M Receive Input and Squelch
The Manchester signal from the cable is fed into the transceiver (on inputs RXP and RXN) via 1:1 ratio
magnetics. It is first filtered to reduce any out-of-band noise. It then passes through a SQUELCH
circuit. The SQUELCH is a set of amplitude and timing comparators that normally reject differential
voltage levels below 300 mV and detect and recognize differential voltages above 585 mV.
3.1.4.2
Manchester Decoding
The output of the SQUELCH goes to the 10M RX block where it is validated as Manchester encoded
data. The polarity of the signal is also checked. If the polarity is reversed (local RXP is connected to
RXN of the remote partner and vice versa), the condition is identified and corrected. The reversed
condition is indicated by the XPOL bit of the Special Control/Status Indications Register. The 10M PLL
is locked onto the received Manchester signal, from which the 20 MHz cock is generated. Using this
clock, the Manchester encoded data is extracted and converted to a 10 MHz NRZI data stream. It is
then converted from serial to 4-bit wide parallel data.
The 10M RX block also detects valid 10BASE-T IDLE signals - Normal Link Pulses (NLPs) - to
maintain the link.
3.1.4.3
10M Receive Data Across the MII/RMII Interface
For MII, the 4-bit data nibbles are sent to the MII block. In MII mode, these data nibbles are valid on
the rising edge of the 2.5 MHz RXCLK.
For RMII, the 2-bit data nibbles are sent to the RMII block. In RMII mode, these data nibbles are valid
on the rising edge of the RMII REF_CLK.
Note: RXDV goes high with the SFD.
3.1.4.4
Jabber Detection
Jabber is a condition in which a station transmits for a period of time longer than the maximum
permissible packet length, usually due to a fault condition, which results in holding the TXEN input for
a long period. Special logic is used to detect the jabber state and abort the transmission to the line
within 45 ms. Once TXEN is deasserted, the logic resets the jabber condition.
As shown in Section 4.2.2, "Basic Status Register," on page 71, the Jabber Detect bit indicates that a
jabber condition was detected.
3.2
Auto-Negotiation
The purpose of the auto-negotiation function is to automatically configure the transceiver to the
optimum link parameters based on the capabilities of its link partner. Auto-negotiation is a mechanism
for exchanging configuration information between two link-partners and automatically selecting the
highest performance mode of operation supported by both sides. Auto-negotiation is fully defined in
clause 28 of the IEEE 802.3 specification.
Once auto-negotiation has completed, information about the resolved link can be passed back to the
controller via the Serial Management Interface (SMI). The results of the negotiation process are
reflected in the Speed Indication bits of the PHY Special Control/Status Register, as well as in the Auto
Negotiation Link Partner Ability Register. The auto-negotiation protocol is a purely physical layer
activity and proceeds independently of the MAC controller.
The advertised capabilities of the transceiver are stored in the Auto Negotiation Advertisement
Register. The default advertised by the transceiver is determined by user-defined on-chip signal
options.
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The following blocks are activated during an auto-negotiation session:
Auto-negotiation (digital)
100M ADC (analog)
100M PLL (analog)
100M equalizer/BLW/clock recovery (DSP)
10M SQUELCH (analog)
10M PLL (analog)
10M Transmitter (analog)
When enabled, auto-negotiation is started by the occurrence of one of the following events:
Hardware reset
Software reset
Power-down reset
Link status down
Setting the Restart Auto-Negotiate bit of the Basic Control Register
On detection of one of these events, the transceiver begins auto-negotiation by transmitting bursts of
Fast Link Pulses (FLP), which are bursts of link pulses from the 10M transmitter. They are shaped as
Normal Link Pulses and can pass uncorrupted down CAT-3 or CAT-5 cable. A Fast Link Pulse Burst
consists of up to 33 pulses. The 17 odd-numbered pulses, which are always present, frame the FLP
burst. The 16 even-numbered pulses, which may be present or absent, contain the data word being
transmitted. Presence of a data pulse represents a “1”, while absence represents a “0”.
The data transmitted by an FLP burst is known as a “Link Code Word.” These are defined fully in IEEE
802.3 clause 28. In summary, the transceiver advertises 802.3 compliance in its selector field (the first
5 bits of the Link Code Word). It advertises its technology ability according to the bits set in the Auto
Negotiation Advertisement Register.
There are 4 possible matches of the technology abilities. In the order of priority these are:
100M Full Duplex (Highest Priority)
100M Half Duplex
10M Full Duplex
10M Half Duplex (Lowest Priority)
If the full capabilities of the transceiver are advertised (100M, Full Duplex), and if the link partner is
capable of 10M and 100M, then auto-negotiation selects 100M as the highest performance mode. If
the link partner is capable of half and full duplex modes, then auto-negotiation selects full duplex as
the highest performance operation.
Once a capability match has been determined, the link code words are repeated with the acknowledge
bit set. Any difference in the main content of the link code words at this time will cause auto-negotiation
to re-start. Auto-negotiation will also re-start if not all of the required FLP bursts are received.
The capabilities advertised during auto-negotiation by the transceiver are initially determined by the
logic levels latched on the MODE[2:0] configuration straps after reset completes. These configuration
straps can also be used to disable auto-negotiation on power-up. Refer to Section 3.7.2, "MODE[2:0]:
Mode Configuration," on page 40 for additional information.
Writing the bits 8 through 5 of the Auto Negotiation Advertisement Register allows software control of
the capabilities advertised by the transceiver. Writing the Auto Negotiation Advertisement Register
does not automatically re-start auto-negotiation. The Restart Auto-Negotiate bit of the Basic Control
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Register must be set before the new abilities will be advertised. Auto-negotiation can also be disabled
via software by clearing the Auto-Negotiation Enable bit of the Basic Control Register.
3.2.1
Parallel Detection
If the LAN8740A/LAN8740Ai is connected to a device lacking the ability to auto-negotiate (i.e., no FLPs
are detected), it is able to determine the speed of the link based on either 100M MLT-3 symbols or
10M Normal Link Pulses. In this case the link is presumed to be half duplex per the IEEE standard.
This ability is known as “Parallel Detection.” This feature ensures interoperability with legacy link
partners. If a link is formed via parallel detection, then the Link Partner Auto-Negotiation Able bit of the
Auto Negotiation Expansion Register is cleared to indicate that the Link Partner is not capable of autonegotiation. The controller has access to this information via the management interface. If a fault
occurs during parallel detection, the Parallel Detection Fault bit of Link Partner Auto-Negotiation Able
is set.
Auto Negotiation Link Partner Ability Register is used to store the link partner ability information, which
is coded in the received FLPs. If the link partner is not auto-negotiation capable, then the Auto
Negotiation Link Partner Ability Register is updated after completion of parallel detection to reflect the
speed capability of the link partner.
3.2.2
Restarting Auto-Negotiation
Auto-negotiation can be restarted at any time by setting the Restart Auto-Negotiate bit of the Basic
Control Register. Auto-negotiation will also restart if the link is broken at any time. A broken link is
caused by signal loss. This may occur because of a cable break, or because of an interruption in the
signal transmitted by the link partner. Auto-negotiation resumes in an attempt to determine the new
link configuration.
If the management entity re-starts auto-negotiation by setting the Restart Auto-Negotiate bit of the
Basic Control Register, the LAN8740A/LAN8740Ai will respond by stopping all transmission/receiving
operations. Once the break_link_timer is completed in the auto-negotiation state-machine
(approximately 1250 ms), auto-negotiation will re-start. In this case, the link partner will have also
dropped the link due to lack of a received signal, so it too will resume auto-negotiation.
3.2.3
Disabling Auto-Negotiation
Auto-negotiation can be disabled by setting the Auto-Negotiation Enable bit of the Basic Control
Register to zero. The device will then force its speed of operation to reflect the information in the Basic
Control Register (Speed Select bit and Duplex Mode bit). These bits should be ignored when autonegotiation is enabled.
3.2.4
Half vs. Full Duplex
Half duplex operation relies on the CSMA/CD (Carrier Sense Multiple Access / Collision Detect)
protocol to handle network traffic and collisions. In this mode, the carrier sense signal, CRS, responds
to both transmit and receive activity. If data is received while the transceiver is transmitting, a collision
results.
In full duplex mode, the transceiver is able to transmit and receive data simultaneously. In this mode,
CRS responds only to receive activity. The CSMA/CD protocol does not apply and collision detection
is disabled.
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3.3
HP Auto-MDIX Support
HP Auto-MDIX facilitates the use of CAT-3 (10BASE-T) or CAT-5 (100BASE-TX) media UTP
interconnect cable without consideration of interface wiring scheme. If a user plugs in either a direct
connect LAN cable, or a cross-over patch cable, as shown in Figure 3.4, the device’s Auto-MDIX
transceiver is capable of configuring the TXP/TXN and RXP/RXN pins for correct transceiver operation.
The internal logic of the device detects the TX and RX pins of the connecting device. Since the RX
and TX line pairs are interchangeable, special PCB design considerations are needed to accommodate
the symmetrical magnetics and termination of an Auto-MDIX design.
The Auto-MDIX function can be disabled via the AMDIXCTRL bit in the Special Control/Status
Indications Register.
Note: When operating in 10BASE-T or 100BASE-TX manual modes, the Auto-MDIX crossover time
can be extended via the Extend Manual 10/100 Auto-MDIX Crossover Time bit of the EDPD
NLP / Crossover Time / EEE Configuration Register. Refer to Section 4.2.12, "EDPD NLP /
Crossover Time / EEE Configuration Register," on page 82 for additional information.
RJ-45 8-pin straight-through
for 10BASE-T/100BASE-TX
signaling
RJ-45 8-pin cross-over for
10BASE-T/100BASE-TX
signaling
TXP
1
1
TXP
TXP
1
1
TXP
TXN
2
2
TXN
TXN
2
2
TXN
RXP
3
3
RXP
RXP
3
3
RXP
Not Used
4
4
Not Used
Not Used
4
4
Not Used
Not Used
5
5
Not Used
Not Used
5
5
Not Used
RXN
6
6
RXN
RXN
6
6
RXN
Not Used
7
7
Not Used
Not Used
7
7
Not Used
Not Used
8
8
Not Used
Not Used
8
8
Not Used
Direct Connect Cable
Cross-Over Cable
Figure 3.4 Direct Cable Connection vs. Cross-over Cable Connection
3.4
MAC Interface
The MII/RMII block is responsible for communication with the MAC controller. Special sets of handshake signals are used to indicate that valid received/transmitted data is present on the 4 bit
receive/transmit bus.
The device must be configured in MII or RMII mode. This is done by specific pin strapping
configurations. Refer to Section 3.4.3, "MII vs. RMII Configuration," on page 34 for information on pin
strapping and how the pins are mapped differently.
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3.4.1
MII
The MII includes 16 interface signals:
Transmit data - TXD[3:0]
Transmit strobe - TXEN
Transmit clock - TXCLK
Transmit error - TXER/TXD4
Receive data - RXD[3:0]
Receive strobe - RXDV
Receive clock - RXCLK
Receive error - RXER/RXD4/PHYAD0
Collision indication - COL
Carrier sense - CRS
In MII mode, on the transmit path, the transceiver drives the transmit clock, TXCLK, to the controller.
The controller synchronizes the transmit data to the rising edge of TXCLK. The controller drives TXEN
high to indicate valid transmit data. The controller drives TXER high when a transmit error is detected.
On the receive path, the transceiver drives both the receive data, RXD[3:0], and the RXCLK signal.
The controller clocks in the receive data on the rising edge of RXCLK when the transceiver drives
RXDV high. The transceiver drives RXER high when a receive error is detected.
3.4.2
RMII
The device supports the low pin count Reduced Media Independent Interface (RMII) intended for use
between Ethernet transceivers and switch ASICs. Under IEEE 802.3, an MII comprised of 16 pins for
data and control is defined. In devices incorporating many MACs or transceiver interfaces such as
switches, the number of pins can add significant cost as the port counts increase. RMII reduces this
pin count while retaining a management interface (MDIO/MDC) that is identical to MII.
The RMII interface has the following characteristics:
It is capable of supporting 10 Mbps and 100 Mbps data rates
A single clock reference is used for both transmit and receive
It provides independent 2-bit (di-bit) wide transmit and receive data paths
It uses LVCMOS signal levels, compatible with common digital CMOS ASIC processes
The RMII includes the following interface signals (1 optional):
Transmit data - TXD[1:0]
Transmit strobe - TXEN
Receive data - RXD[1:0]
Receive error - RXER (Optional)
Carrier sense - CRS_DV
Reference Clock - (RMII references usually define this signal as REF_CLK)
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3.4.2.1
CRS_DV - Carrier Sense/Receive Data Valid
The CRS_DV is asserted by the device when the receive medium is non-idle. CRS_DV is asserted
asynchronously on detection of carrier due to the criteria relevant to the operating mode. In 10BASET mode when squelch is passed, or in 100BASE-TX mode when 2 non-contiguous zeroes in 10 bits
are detected, the carrier is said to be detected.
Loss of carrier shall result in the deassertion of CRS_DV synchronous to the cycle of REF_CLK which
presents the first di-bit of a nibble onto RXD[1:0] (i.e., CRS_DV is deasserted only on nibble
boundaries). If the device has additional bits to be presented on RXD[1:0] following the initial
deassertion of CRS_DV, then the device shall assert CRS_DV on cycles of REF_CLK which present
the second di-bit of each nibble and de-assert CRS_DV on cycles of REF_CLK which present the first
di-bit of a nibble. The result is, starting on nibble boundaries, CRS_DV toggles at 25 MHz in 100 Mbps
mode and 2.5 MHz in 10 Mbps mode when CRS ends before RXDV (i.e., the FIFO still has bits to
transfer when the carrier event ends). Therefore, the MAC can accurately recover RXDV and CRS.
During a false carrier event, CRS_DV shall remain asserted for the duration of carrier activity. The data
on RXD[1:0] is considered valid once CRS_DV is asserted. However, since the assertion of CRS_DV
is asynchronous relative to REF_CLK, the data on RXD[1:0] shall be “00” until proper receive signal
decoding takes place.
3.4.2.2
Reference Clock (REF_CLK)
The RMII REF_CLK is a continuous clock that provides the timing reference for CRS_DV, RXD[1:0],
TXEN, TXD[1:0] and RXER. The device uses REF_CLK as the network clock such that no buffering
is required on the transmit data path. However, on the receive data path, the receiver recovers the
clock from the incoming data stream, and the device uses elasticity buffering to accommodate for
differences between the recovered clock and the local REF_CLK.
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3.4.3
MII vs. RMII Configuration
The device must be configured to support the MII or RMII bus for connectivity to the MAC. This
configuration is done via the RMIISEL configuration strap. MII or RMII mode selection is configured
based on the strapping of the RMIISEL configuration strap as described in Section 3.7.3, "RMIISEL:
MII/RMII Mode Configuration," on page 41. Additionally, the MII/RMII interface can be disabled (outputs
driven low) via the Interface Disable bit of the Wakeup Control and Status Register (WUCSR).
Most of the MII and RMII pins are multiplexed. Table 3.2, "MII/RMII Signal Mapping" describes the
relationship of the related device pins to the MII and RMII mode signal names.
Table 3.2 MII/RMII Signal Mapping
PIN NAME
MII MODE
RMII MODE
TXD0
TXD0
TXD0
TXD1
TXD1
TXD1
TXEN
TXEN
TXEN
RXER/
RXD4/PHYAD0
RXER
RXER
Note 3.2
COL/CRS_DV/MODE2
COL
CRS_DV
RXD0/MODE0
RXD0
RXD0
RXD1/MODE1
RXD1
RXD1
TXD2
TXD2
Note 3.1
TXD3
TXD3
Note 3.1
nINT/TXER/TXD4
TXER/
TXD4
CRS
CRS
RXDV
RXDV
RXD2/RMIISEL
RXD2
RXD3/PHYAD2
RXD3
TXCLK
TXCLK
RXCLK/PHYAD1
RXCLK
XTAL1/CLKIN
XTAL1/CLKIN
REF_CLK
Note 3.1
In RMII mode, this pin needs to be tied to VSS.
Note 3.2
The RXER signal is optional on the RMII bus. This signal is required by the transceiver,
but it is optional for the MAC. The MAC can choose to ignore or not use this signal.
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Datasheet
3.5
Serial Management Interface (SMI)
The Serial Management Interface is used to control the device and obtain its status. This interface
supports registers 0 through 6 as required by clause 22 of the 802.3 standard, as well as “vendorspecific” registers 16 to 31 allowed by the specification. Device registers are detailed in Chapter 4,
"Register Descriptions," on page 68.
At the system level, SMI provides 2 signals: MDIO and MDC. The MDC signal is an aperiodic clock
provided by the Station Management Controller (SMC). MDIO is a bi-directional data SMI input/output
signal that receives serial data (commands) from the controller SMC and sends serial data (status) to
the SMC. The minimum time between edges of the MDC is 160 ns. There is no maximum time
between edges. The minimum cycle time (time between two consecutive rising or two consecutive
falling edges) is 400 ns. These modest timing requirements allow this interface to be easily driven by
the I/O port of a microcontroller.
The data on the MDIO line is latched on the rising edge of the MDC. The frame structure and timing
of the data is shown in Figure 3.5 and Figure 3.6. The timing relationships of the MDIO signals are
further described in Section 5.6.5, "SMI Timing," on page 136.
Read Cycle
MDC
MDIO
32 1's
Preamble
0
1
1
Start of
Frame
0
OP
Code
A4 A3 A2 A1 A0 R4 R3 R2 R1 R0
PHY Address
Register Address
D15
D14
Turn
Around
...
...
D1
D0
Data
Data From Phy
Data To Phy
Figure 3.5 MDIO Timing and Frame Structure - READ Cycle
Write Cycle
MDC
MDIO
32 1's
Preamble
0
1
0
Start of
Frame
1
OP
Code
A4 A3 A2 A1 A0 R4 R3 R2 R1 R0
PHY Address
Register Address
D15
D14
Turn
Around
...
...
D1
D0
Data
Data To Phy
Figure 3.6 MDIO Timing and Frame Structure - WRITE Cycle
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3.6
Interrupt Management
The device management interface supports an interrupt capability that is not a part of the IEEE 802.3
specification. This interrupt capability generates an active low asynchronous interrupt signal on the
nINT output whenever certain events are detected as setup by the Interrupt Mask Register.
The nINT signal can be selected to output on three different pins:
nINT/TXER/TXD4
(See Section 3.7.5, "nINTSEL: nINT/TXER/TXD4 Configuration," on page 42 for configuration
information)
LED1
(See Section 3.8.1, "LEDs," on page 43 for configuration information)
LED2
(See Section 3.8.1, "LEDs," on page 43 for configuration information)
The device’s interrupt system provides two modes, a Primary interrupt mode and an Alternative
interrupt mode. Both systems will assert the nINT pin low when the corresponding mask bit is set.
These modes differ only in how they de-assert the nINT interrupt output. These modes are detailed in
the following subsections.
Note: The Primary interrupt mode is the default interrupt mode after a power-up or hard reset. The
Alternative interrupt mode requires setup after a power-up or hard reset.
Note: In addition to the main interrupts described in this section, an nPME pin is provided exclusively
for WoL specific interrupts. Refer to Section 3.8.4, "Wake on LAN (WoL)," on page 48 for
additional information on nPME.
Note: Due to the multiplexing of nINT and TXER on the same pin, when EEE and WoL are both
enabled, nINT and/or nPME must be multiplexed on LED1 and/or LED2. Refer to Section 3.8.1,
"LEDs," on page 43 and Section 3.8.4, "Wake on LAN (WoL)," on page 48 for additional
information.
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Datasheet
3.6.1
Primary Interrupt System
The Primary interrupt system is the default interrupt mode (ALTINT bit of the Mode Control/Status
Register is “0”). The Primary interrupt system is always selected after power-up or hard reset. In this
mode, to set an interrupt, set the corresponding mask bit in the Interrupt Mask Register (see Table 3.3).
Then when the event to assert nINT is true, the nINT output will be asserted. When the corresponding
event to deassert nINT is true, then the nINT will be de-asserted.
Table 3.3 Interrupt Management Table
MASK
INTERRUPT SOURCE
FLAG
INTERRUPT SOURCE
EVENT TO
ASSERT nINT
EVENT TO
DE-ASSERT nINT
30.8
29.8
WoL
3.32784
.7:4
nPME
Rising
3.32784.7:4
or’ed together
3.32784.7:4 or’ed
together low or reading
register 29
30.7
29.7
ENERGYON
17.1
ENERGYON
Rising 17.1
(Note 3.3)
Falling 17.1 or
Reading register 29
30.6
29.6
Auto-Negotiation
complete
1.5
Auto-Negotiate
Complete
Rising 1.5
Falling 1.5 or
Reading register 29
30.5
29.5
Remote Fault
Detected
1.4
Remote Fault
Rising 1.4
Falling 1.4, or
Reading register 1 or
Reading register 29
30.4
29.4
Link Down
1.2
Link Status
Falling 1.2
Reading register 1 or
Reading register 29
30.3
29.3
Auto-Negotiation
LP Acknowledge
5.14
Acknowledge
Rising 5.14
Falling 5.14 or
Reading register 29
30.2
29.2
Parallel
Detection Fault
6.4
Parallel
Detection Fault
Rising 6.4
Falling 6.4 or
Reading register 6, or
Reading register 29, or
Re-Auto Negotiate or
Link down
30.1
29.1
Auto-Negotiation
Page Received
6.1
Page Received
Rising 6.1
Falling 6.1 or
Reading register 6, or
Reading register 29, or
Re-Auto Negotiate, or
Link down.
Note 3.3
If the mask bit is enabled and nINT has been de-asserted while ENERGYON is still high,
nINT will assert for 256 ms, approximately one second after ENERGYON goes low when
the Cable is unplugged. To prevent an unexpected assertion of nINT, the ENERGYON
interrupt mask should always be cleared as part of the ENERGYON interrupt service
routine.
Note: The ENERGYON bit in the Mode Control/Status Register is defaulted to a ‘1’ at the start of the
signal acquisition process, therefore the INT7 bit in the Interrupt Mask Register will also read
as a ‘1’ at power-up. If no signal is present, then both ENERGYON and INT7 will clear within
a few milliseconds.
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3.6.2
Alternate Interrupt System
The Alternate interrupt system is enabled by setting the ALTINT bit of the Mode Control/Status Register
to “1”. In this mode, to set an interrupt, set the corresponding bit of the in the Mask Register 30, (see
Table 3.4). To Clear an interrupt, either clear the corresponding bit in the Interrupt Mask Register to
deassert the nINT output, or clear the interrupt source, and write a ‘1’ to the corresponding Interrupt
Source Flag. Writing a ‘1’ to the Interrupt Source Flag will cause the state machine to check the
Interrupt Source to determine if the Interrupt Source Flag should clear or stay as a ‘1’. If the Condition
to deassert is true, then the Interrupt Source Flag is cleared and nINT is also deasserted. If the
Condition to deassert is false, then the Interrupt Source Flag remains set, and the nINT remains
asserted.
For example, setting the INT7 bit in the Interrupt Mask Register will enable the ENERGYON interrupt.
After a cable is plugged in, the ENERGYON bit in the Mode Control/Status Register goes active and
nINT will be asserted low. To de-assert the nINT interrupt output, either clear the ENERGYON bit in
the Mode Control/Status Register by removing the cable and then writing a ‘1’ to the INT7 bit in the
Interrupt Mask Register, OR clear the INT7 mask (bit 7 of the Interrupt Mask Register).
Table 3.4 Alternative Interrupt System Management Table
MASK
INTERRUPT SOURCE
FLAG
INTERRUPT SOURCE
EVENT TO
ASSERT
nINT
CONDITION
TO
DEASSERT
BIT TO
CLEAR
nINT
30.8
29.8
WoL
3.32784.
7:4
nPME
Rising
3.32784.7:4
or’ed
3.32784.7:4
all low
29.8
30.7
29.7
ENERGYON
17.1
ENERGYON
Rising 17.1
17.1 low
29.7
30.6
29.6
Auto-Negotiation
complete
1.5
Auto-Negotiate
Complete
Rising 1.5
1.5 low
29.6
30.5
29.5
Remote Fault
Detected
1.4
Remote Fault
Rising 1.4
1.4 low
29.5
30.4
29.4
Link Down
1.2
Link Status
Falling 1.2
1.2 high
29.4
30.3
29.3
Auto-Negotiation
LP Acknowledge
5.14
Acknowledge
Rising 5.14
5.14 low
29.3
30.2
29.2
Parallel
Detection Fault
6.4
Parallel Detection
Fault
Rising 6.4
6.4 low
29.2
30.1
29.1
Auto-Negotiation
Page Received
6.1
Page Received
Rising 6.1
6.1 low
29.1
Note: The ENERGYON bit in the Mode Control/Status Register is defaulted to a ‘1’ at the start of the
signal acquisition process, therefore the INT7 bit in the Interrupt Mask Register will also read
as a ‘1’ at power-up. If no signal is present, then both ENERGYON and INT7 will clear within
a few milliseconds.
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3.7
Configuration Straps
Configuration straps allow various features of the device to be automatically configured to user defined
values. Configuration straps are latched upon Power-On Reset (POR) and pin reset (nRST).
Configuration straps include internal resistors in order to prevent the signal from floating when
unconnected. If a particular configuration strap is connected to a load, an external pull-up or pull-down
resistor should be used to augment the internal resistor to ensure that it reaches the required voltage
level prior to latching. The internal resistor can also be overridden by the addition of an external
resistor.
Note: The system designer must guarantee that configuration strap pins meet the timing
requirements specified in Section 5.6.2, "Power-On nRST & Configuration Strap Timing," on
page 130. If configuration strap pins are not at the correct voltage level prior to being latched,
the device may capture incorrect strap values.
Note: When externally pulling configuration straps high, the strap should be tied to VDDIO, except
for REGOFF and nINTSEL which should be tied to VDD2A.
3.7.1
PHYAD[2:0]: PHY Address Configuration
The PHYAD[2:0] configuration straps are driven high or low to give each PHY a unique address. This
address is latched into an internal register at the end of a hardware reset (default = 000b). In a multitransceiver application (such as a repeater), the controller is able to manage each transceiver via the
unique address. Each transceiver checks each management data frame for a matching address in the
relevant bits. When a match is recognized, the transceiver responds to that particular frame. The PHY
address is also used to seed the scrambler. In a multi-transceiver application, this ensures that the
scramblers are out of synchronization and disperses the electromagnetic radiation across the
frequency spectrum.
The device’s SMI address may be configured using hardware configuration to any value between 0
and 7. The user can configure the PHY address using Software Configuration if an address greater
than 7 is required. The PHY address can be written (after SMI communication at some address is
established) using the PHYAD bits of the Special Modes Register. The PHYAD[2:0] configuration straps
are multiplexed with other signals as shown in Table 3.5.
Table 3.5 Pin Names for Address Bits
SMSC LAN8740A/LAN8740Ai
ADDRESS BIT
PIN NAME
PHYAD[0]
RXER/RXD4/PHYAD0
PHYAD[1]
RXCLK/PHYAD1
PHYAD[2]
RXD3/PHYAD2
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3.7.2
MODE[2:0]: Mode Configuration
The MODE[2:0] configuration straps control the configuration of the 10/100 digital block. When the
nRST pin is deasserted, the register bit values are loaded according to the MODE[2:0] configuration
straps. The 10/100 digital block is then configured by the register bit values. When a soft reset occurs
via the Soft Reset bit of the Basic Control Register, the configuration of the 10/100 digital block is
controlled by the register bit values and the MODE[2:0] configuration straps have no affect.
The device’s mode may be configured using the hardware configuration straps as summarized in
Table 3.6. The user may configure the transceiver mode by writing the SMI registers.
Table 3.6 MODE[2:0] Bus
DEFAULT REGISTER BIT VALUES
MODE DEFINITIONS
MODE[2:0]
REGISTER 0
REGISTER 4
[13,12,10,8]
[8,7,6,5]
000
10BASE-T Half Duplex. Auto-negotiation disabled.
0000
N/A
001
10BASE-T Full Duplex. Auto-negotiation disabled.
0001
N/A
010
100BASE-TX Half Duplex. Auto-negotiation
disabled.
CRS is active during Transmit & Receive.
1000
N/A
011
100BASE-TX Full Duplex. Auto-negotiation
disabled.
CRS is active during Receive.
1001
N/A
100
100BASE-TX Half Duplex is advertised. Autonegotiation enabled.
CRS is active during Transmit & Receive.
1100
0100
101
Repeater mode. Auto-negotiation enabled.
100BASE-TX Half Duplex is advertised.
CRS is active during Receive.
1100
0100
110
Power-Down mode. In this mode the transceiver
will wake-up in Power-Down mode. The transceiver
cannot be used when the MODE[2:0] bits are set to
this mode. To exit this mode, the MODE bits in
Register 18.7:5 (see Section 4.2.14, "Special
Modes Register," on page 84) must be configured
to some other value and a soft reset must be
issued.
N/A
N/A
111
All capable. Auto-negotiation enabled.
X10X
1111
The MODE[2:0] hardware configuration pins are multiplexed with other signals as shown in Table 3.7.
Table 3.7 Pin Names for Mode Bits
Revision 1.1 (05-10-13)
MODE BIT
PIN NAME
MODE[0]
RXD0/MODE0
MODE[1]
RXD1/MODE1
MODE[2]
COL/CRS_DV/MODE2
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3.7.3
RMIISEL: MII/RMII Mode Configuration
MII or RMII mode selection is latched on the rising edge of the internal reset (nRST) based on the
strapping of the RMIISEL configuration strap. The default mode is MII (via the internal pull-down
resistor). To select RMII mode, pull the RMIISEL configuration strap high with an external resistor to
VDDIO.
When the nRST pin is deasserted, the MIIMODE bit of the Special Modes Register is loaded according
to the RMIISEL configuration strap. The mode is reflected in the MIIMODE bit of the Special Modes
Register.
Refer to Section 3.4, "MAC Interface," on page 31 for additional information on MII and RMII modes.
3.7.4
REGOFF: Internal +1.2 V Regulator Configuration
The incorporation of flexPWR technology provides the ability to disable the internal +1.2 V regulator.
When the regulator is disabled, an external +1.2 V must be supplied to the VDDCR pin. Disabling the
internal +1.2 V regulator makes it possible to reduce total system power, since an external switching
regulator with greater efficiency (versus the internal linear regulator) can be used to provide +1.2 V to
the transceiver circuitry.
Note: Because the REGOFF configuration strap shares functionality with the LED1 pin, proper
consideration must also be given to the LED polarity. Refer to Section 3.8.1, "LEDs," on
page 43 for additional information on the relation between REGOFF and the LED1 polarity.
3.7.4.1
Disabling the Internal +1.2 V Regulator
To disable the +1.2 V internal regulator, a pull-up strapping resistor should be connected from the
REGOFF configuration strap to VDD2A. At power-on, after both VDDIO and VDD2A are within
specification, the transceiver will sample REGOFF to determine whether the internal regulator should
turn on. If the pin is sampled at a voltage greater than VIH, then the internal regulator is disabled and
the system must supply +1.2 V to the VDDCR pin. The VDDIO voltage must be at least 80% of the
operating voltage level (1.44 V when operating at 1.8 V, 2.0 V when operating at 2.5 V, 2.64 V when
operating at 3.3 V) before voltage is applied to VDDCR. As described in Section 3.7.4.2, when
REGOFF is left floating or connected to VSS, the internal regulator is enabled and the system is not
required to supply +1.2 V to the VDDCR pin.
3.7.4.2
Enabling the Internal +1.2 V Regulator
The +1.2 V for VDDCR is supplied by the on-chip regulator unless the transceiver is configured for the
regulator off mode using the REGOFF configuration strap as described in Section 3.7.4.1. By default,
the internal +1.2 V regulator is enabled when REGOFF is floating (due to the internal pull-down
resistor). During power-on, if REGOFF is sampled below VIL, then the internal +1.2 V regulator will
turn on and operate with power from the VDD2A pin.
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3.7.5
nINTSEL: nINT/TXER/TXD4 Configuration
The nINT, TXER, and TXD4 functions share a common pin. There are two functional modes for this
pin, the TXER/TXD4 mode and nINT (interrupt) mode. The nINTSEL configuration strap is latched at
POR and on the rising edge of the nRST. By default, nINTSEL is configured for nINT mode via the
internal pull-up resistor.
Note: In order to utilize EEE, the nINT/TXER/TXD4 pin must be configured as TXER/TXD4.
Note: Due to the multiplexing of nINT and TXER on the same pin, when EEE and WoL are both
enabled, nINT and/or nPME must be multiplexed on LED1 and/or LED2. Refer to Section 3.6,
"Interrupt Management," on page 36 and Section 3.8.4, "Wake on LAN (WoL)," on page 48 for
additional information.
Note: Because the nINTSEL configuration strap shares functionality with the LED2 pin, proper
consideration must also be given to the LED polarity. Refer to Section 3.8.1.6, "nINTSEL and
LED2 Polarity Selection," on page 47 for additional information on the relation between
nINTSEL and the LED2 polarity.
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3.8
Miscellaneous Functions
3.8.1
LEDs
Two LED signals are provided as a convenient means to indicate the transceiver's mode of operation
or be used as nINT or nPME signals. The LED1 and LED2 pin functions are configurable via the LED1
Function Select and LED2 Function Select bits of the Wakeup Control and Status Register (WUCSR),
respectively. When used as an LED indicator, the LED signals are either active high or active low as
described in Section 3.8.1.5, "REGOFF and LED1 Polarity Selection," on page 46 and Section 3.8.1.6,
"nINTSEL and LED2 Polarity Selection," on page 47. For additional information on nINT, refer to
Section 3.6, "Interrupt Management," on page 36. For additional information on nPME, refer to Section
3.8.4, "Wake on LAN (WoL)," on page 48.
When configured in the default Link/Activity mode, the LED1 output is driven active whenever the
device detects a valid link, and blinks when CRS is active (high) indicating activity.
When configured in the default Link Speed mode, the LED2 output is driven active when the operating
speed is 100 Mbps. This LED will go inactive when the operating speed is 10 Mbps or during line
isolation.
Note: When pulling the LED1 and LED2 pins high, they must be tied to VDD2A, NOT VDDIO.
Note: Due to the multiplexing of nINT and TXER on the same pin, when EEE and WoL are both
enabled, nINT and/or nPME must be multiplexed on LED1 and/or LED2. Refer to Section 3.6,
"Interrupt Management," on page 36 and Section 3.8.4, "Wake on LAN (WoL)," on page 48 for
additional information.
3.8.1.1
LED1/nINT/nPME Usage with Internal Regulator Disabled (REGOFF High)
When the LED1/nINT/nPME/REGOFF pin is high during reset, the internal regulator is disabled. After
the deassertion of reset, this pin will first function as LED1 (Link Activity). Upon configuration, it can
function as nINT or nPME. Figure 3.7 illustrates the steps required to program the LED1 pin as nINT
or nPME with the internal regulator disabled.
In this configuration, it is possible for an LED to be connected to this pin while it function as nINT or
nPME during the WoL state. Since the polarity to turn on the LED is active low, the Link Activity LED
will not be lit while waiting for a WoL event.
Note: Refer to Section 3.7.4, "REGOFF: Internal +1.2 V Regulator Configuration," on page 41 for
additional information on the REGOFF configuration strap.
nRST
Link Activity
nINT/nPME
00b
01b/10b
Link Activity
LED1/nINT/
nPME/REGOFF
WUCSR[14:13]
00b
Figure 3.7 LED1/nINT/nPME/REGOFF with Internal Regulator Disabled
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3.8.1.2
LED1/nINT/nPME Usage with Internal Regulator Enabled (REGOFF Low)
When the LED1/nINT/nPME/REGOFF pin is low during reset, the internal regulator is enabled. After
the deassertion of reset, this pin will first function as LED1 (Link Activity). Upon configuration, it can
function as nINT or nPME. Figure 3.8 illustrates the steps required to program the LED1 pin as nINT
or nPME with the internal regulator enabled.
In this configuration, it is recommended not to connect an LED to this pin. Because this pin is active
high, the LED will be lit while waiting for a WoL event.
Note: Refer to Section 3.7.4, "REGOFF: Internal +1.2 V Regulator Configuration," on page 41 for
additional information on the REGOFF configuration strap.
nRST
Link Activity
nINT/nPME
00b
01b/10b
LED1/nINT/
nPME/REGOFF
WUCSR[14:13]
Figure 3.8 LED1/nINT/nPME/REGOFF with Internal Regulator Enabled
3.8.1.3
LED2/nINT/nPME Usage with nINTSEL Enabled
When the LED2/nINT/nPME/nINTSEL pin is high during reset, the nINT/TXER/TXD4 pin is configured
to function as nINT. After the deassertion of reset, this pin will first function as LED2 (Link Speed).
Upon configuration, it can function as nPME. It is also possible to configure LED2 as nINT although
this would duplicate the function of the nINT/TXER/TXD4 pin. Figure 3.9 illustrates the steps required
to program the LED2 pin as nINT or nPME with nINTSEL enabled.
In this configuration, it is possible for an LED be connected to this pin while it functions as nINT or
nPME during a WoL state. Since the polarity to light the LED is active low, the Link Speed LED will
not be lit while waiting for a WoL event.
To provide further flexibility, LED2 can be reconfigured as Link Activity by writing 11b to the LED2
Function Select field of the Wakeup Control and Status Register (WUCSR). This allows LED2 to
function as Link Activity when LED1 cannot be configured as Link Activity. Link Speed can be easily
implemented on the microcontroller using GPIO.
Note: Refer to Section 3.7.5, "nINTSEL: nINT/TXER/TXD4 Configuration," on page 42 for additional
information on the nINTSEL configuration strap.
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Datasheet
nRST
Link Speed/
Link Activity
Link Speed/
Link Activity
nINT/nPME
LED2/nINT/
nPME/nINTSEL
WUCSR[12:11]
00b
00b/11b
01b/10b
00b/11b
Figure 3.9 LED2/nINT/nPME with nINTSEL Enabled
3.8.1.4
LED2/nINT/nPME Usage with nINTSEL Disabled
When the LED2/nINT/nPME/nINTSEL pin is low during reset, the nINT/TXER/TXD4 pin is configured
to function as TXER/TXD4. After the deassertion of reset, this pin will first function as LED2. Upon
configuration, it can function as nINT or nPME. Figure 3.10 illustrates the steps required to program
the LED2 pin as nINT or nPME with nINTSEL disabled.
In this configuration, it is not recommended to connect an LED to this pin. Because this pin is active
high, the LED will be lit while waiting for a WoL event.
nRST
Link Speed
nINT/nPME
LED2/nINT/
nPME/nINTSEL
WUCSR[12:11]
00b
01b/10b
Figure 3.10 LED2/nINT/nPME with nINTSEL Disabled
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3.8.1.5
REGOFF and LED1 Polarity Selection
The REGOFF configuration strap is shared with the LED1 pin. The LED1 output will automatically
change polarity based on the presence of an external pull-up resistor. If the LED1 pin is pulled high to
VDD2A by an external pull-up resistor to select a logical high for REGOFF, then the LED1 output will
be active low. If the LED1 pin is pulled low by the internal pull-down resistor to select a logical low for
REGOFF, the LED1 output will then be an active high output. Figure 3.11 details the LED1 polarity for
each REGOFF configuration.
REGOFF = 1 (Regulator OFF)
LED output = Active Low
REGOFF = 0 (Regulator ON)
LED output = Active High
VDD2A
LED1/REGOFF
10K
~270 Ω
~270 Ω
LED1/REGOFF
Figure 3.11 LED1/REGOFF Polarity Configuration
Note: Refer to Section 3.7.4, "REGOFF: Internal +1.2 V Regulator Configuration," on page 41 for
additional information on the REGOFF configuration strap.
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3.8.1.6
nINTSEL and LED2 Polarity Selection
The nINTSEL configuration strap is shared with the LED2 pin. The LED2 output will automatically
change polarity based on the presence of an external pull-down resistor. If the LED2 pin is pulled high
to VDD2A to select a logical high for nINTSEL, then the LED2 output will be active low. If the LED2
pin is pulled low by an external pull-down resistor to select a logical low for nINTSEL, the LED2 output
will then be an active high output. Figure 3.12 details the LED2 polarity for each nINTSEL
configuration.
nINTSEL = 1
LED output = Active Low
nINTSEL = 0
LED output = Active High
VDD2A
LED2/nINTSEL
10K
~270 Ω
~270 Ω
LED2/nINTSEL
Figure 3.12 LED2/nINTSEL Polarity Configuration
Note: Refer to Section 3.7.5, "nINTSEL: nINT/TXER/TXD4 Configuration," on page 42 for additional
information on the nINTSEL configuration strap.
3.8.2
Variable Voltage I/O
The device’s digital I/O pins are variable voltage, allowing them to take advantage of low power savings
from shrinking technologies. These pins can operate from a low I/O voltage of +1.8 V up to +3.3 V.
The applied I/O voltage must maintain its value with a tolerance of ±10%. Varying the voltage up or
down after the transceiver has completed power-on reset can cause errors in the transceiver operation.
Refer to Chapter 5, "Operational Characteristics," on page 124 for additional information.
Note: Input signals must not be driven high before power is applied to the device.
3.8.3
Power-Down Modes
There are two device power-down modes: General Power-Down Mode and Energy Detect PowerDown Mode. These modes are described in the following subsections.
3.8.3.1
General Power-Down
This power-down mode is controlled via the Power Down bit of the Basic Control Register. In this
mode, the entire transceiver (except the management interface) is powered-down and remains in this
mode as long as the Power Down bit is “1”. When the Power Down bit is cleared, the transceiver
powers up and is automatically reset.
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3.8.3.2
Energy Detect Power-Down (EDPD)
This power-down mode is activated by setting the EDPWRDOWN bit of the Mode Control/Status
Register. In this mode, when no energy is present on the line the transceiver is powered down (except
for the management interface, the SQUELCH circuit, and the ENERGYON logic). The ENERGYON
logic is used to detect the presence of valid energy from 100BASE-TX, 10BASE-T, or Auto-negotiation
signals.
In this mode, when the ENERGYON bit of the Mode Control/Status Register is low, the transceiver is
powered-down and nothing is transmitted. When energy is received via link pulses or packets, the
ENERGYON bit goes high and the transceiver powers-up. The device automatically resets into the
state prior to power-down and asserts the nINT interrupt if the ENERGYON interrupt is enabled in the
Interrupt Mask Register. The first and possibly the second packet to activate ENERGYON may be lost.
When the EDPWRDOWN bit of the Mode Control/Status Register is low, energy detect power-down is
disabled.
When in EDPD mode, the device’s NLP characteristics may be modified. The device can be configured
to transmit NLPs in EDPD via the EDPD TX NLP Enable bit of the EDPD NLP / Crossover Time / EEE
Configuration Register. When enabled, the TX NLP time interval is configurable via the EDPD TX NLP
Interval Timer Select field of the EDPD NLP / Crossover Time / EEE Configuration Register. When in
EDPD mode, the device can also be configured to wake on the reception of one or two NLPs. Setting
the EDPD RX Single NLP Wake Enable bit of the EDPD NLP / Crossover Time / EEE Configuration
Register will enable the device to wake on reception of a single NLP. If the EDPD RX Single NLP
Wake Enable bit is cleared, the maximum interval for detecting reception of two NLPs to wake from
EDPD is configurable via the EDPD RX NLP Max Interval Detect Select field of the EDPD NLP /
Crossover Time / EEE Configuration Register.
3.8.4
Wake on LAN (WoL)
The device supports PHY layer WoL event detection of Perfect DA, Broadcast, Magic Packet, and
Wakeup frames. The WoL detection can be configured to assert the nINT interrupt pin or nPME pin,
providing a mechanism for a system in sleep mode to return to an operational state when a WoL event
occurs. This feature is particularly useful in addressing unnecessary waking of the main SoC in designs
where the Ethernet MAC is integrated into the SoC.
Each type of supported wake event (Perfect DA, Broadcast, Magic Packet, or Wakeup frames) may
be individually enabled via Perfect DA Wakeup Enable (PFDA_EN), Broadcast Wakeup Enable
(BCST_EN), Magic Packet Enable (MPEN), and Wakeup Frame Enable (WUEN) bits of the Wakeup
Control and Status Register (WUCSR), respectively. Two methods are provided for indicating a WoL
event to an external device: nINT and nPME.
The nINT pin may be used to indicate WoL interrupt events by setting bit 8 (WoL) of the Interrupt Mask
Register. Once enabled, any received packet that matches the condition(s) configured in the Wakeup
Control and Status Register (WUCSR) will assert nINT until the interrupt is cleared. When using nINT
to indicate a WoL interrupt, the pin may be shared with other non-WoL interrupt events, as configured
via the Interrupt Mask Register. While waiting for a WoL event to occur, it is possible that other
interrupts may be triggered. To prevent such conditions, all other interrupts shall be masked by system
software, or the alternative nPME pin may be used. Refer to Section 3.6, "Interrupt Management," on
page 36 for additional nINT information.
Alternatively, the nPME pin may be used to independently indicate WoL interrupt events. The nPME
signal can be configured to output on any of the following pins:
LED1/nINT/nPME/nREGOFF
LED2/nINT/nPME/nINTSEL
RXD2/nPME/RMIISEL (Refer to Section 3.7.5, "nINTSEL: nINT/TXER/TXD4 Configuration" for
configuration information)
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The LED1/nINT/nPME/nREGOFF or LED2/nINT/nPME/nINTSEL pin can be configured to function as
nPME by configuring the LED1 Function Select or LED2 Function Select bits of the Wakeup Control
and Status Register (WUCSR) to 10b, respectively. The RXD2/nPME/RMIISEL pin can be configured
to function as nPME by setting the RXD2/RMIISEL Function Select bit of the Wakeup Control and
Status Register (WUCSR). The RXD2/nPME/RMIISEL pin can only be used as nPME when in RMII
mode. Once the nPME pin is enabled, any received packet that matches the condition(s) configured
in the Wakeup Control and Status Register (WUCSR) will assert nPME until WUCSR bits 7:4 are
cleared by the system software. However, in some applications it may be desirable for nPME to self
clear. When the nPME Self Clear bit of the Wakeup Control and Status Register (WUCSR) is set, the
nPME pin will clear after the time configured in the Miscellaneous Configuration Register (MCFGR).
Upon a WoL event, further resolution on the source of the event can be obtained by examining the
Perfect DA Frame Received (PFDA_FR), Broadcast Frame Received (BCAST_FR), Magic Packet
Received (MPR), and Remote Wakeup Frame Received (WUFR) status bits in the Wakeup Control
and Status Register (WUCSR).
Note: Due to the multiplexing of nINT and TXER on the same pin, when EEE and WoL are both
enabled, nINT and/or nPME must be multiplexed on LED1 and/or LED2.
The Wakeup Control and Status Register (WUCSR) also provides a WoL Configured bit, which may
be set by software after all WoL registers are configured. Because all WoL related registers are not
affected by software resets, software can poll the WoL Configured bit to ensure all WoL registers are
fully configured. This allows the software to skip reprogramming of the WoL registers after reboot due
to a WoL event.
The following subsections detail each type of WoL event. For additional information on the main system
interrupts, refer to Section 3.6, "Interrupt Management," on page 36.
3.8.4.1
Perfect DA (Destination Address) Detection
When enabled, the Perfect DA detection mode allows the triggering of the nINT or nPME pin when a
frame with the destination address matching the address stored in the MAC Receive Address A
Register (RX_ADDRA), MAC Receive Address B Register (RX_ADDRB), and MAC Receive Address
C Register (RX_ADDRC) is received. The frame must also pass the FCS and packet length check.
As an example, the Host system must perform the following steps to enable the device to assert nINT
on detection of a Perfect DA WoL event:
1. Set the desired MAC address to cause the wake event in the MAC Receive Address A Register
(RX_ADDRA), MAC Receive Address B Register (RX_ADDRB), and MAC Receive Address C
Register (RX_ADDRC).
2. Set the Perfect DA Wakeup Enable (PFDA_EN) bit of the Wakeup Control and Status Register
(WUCSR) to enable Perfect DA detection.
3. Set bit 8 (WoL event indicator) in the Interrupt Mask Register to enable WoL events to trigger
assertion of the nINT interrupt pin.
When a match is triggered, the nINT interrupt pin will be asserted, bit 8 of the Interrupt Source Flag
Register will be set, and the Perfect DA Frame Received (PFDA_FR) bit of the Wakeup Control and
Status Register (WUCSR) will be set.
Note: Alternatively, the LED1/nINT/nPME, LED2/nINT/nPME, or RXD2/nPME pin can be used to
indicate a WoL event. Refer to Section 3.8.4, "Wake on LAN (WoL)" for additional information.
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3.8.4.2
Broadcast Detection
When enabled, the Broadcast detection mode allows the triggering of the nINT or nPME pin when a
frame with the destination address value of FF FF FF FF FF FF is received. The frame must also pass
the FCS and packet length check.
As an example, the Host system must perform the following steps to enable the device to assert nINT
on detection of a Broadcast WoL event:
1. Set the Broadcast Wakeup Enable (BCST_EN) bit of the Wakeup Control and Status Register
(WUCSR) to enable Broadcast detection.
2. Set bit 8 (WoL event indicator) in the Interrupt Mask Register to enable WoL events to trigger
assertion of the nINT interrupt pin.
When a match is triggered, the nINT interrupt pin will be asserted, bit 8 of the Interrupt Source Flag
Register will be set, and the Broadcast Frame Received (BCAST_FR) bit of the Wakeup Control and
Status Register (WUCSR) will be set.
Note: Alternatively, the LED1/nINT/nPME, LED2/nINT/nPME, or RXD2/nPME pin can be used to
indicate a WoL event. Refer to Section 3.8.4, "Wake on LAN (WoL)" for additional information.
3.8.4.3
Magic Packet Detection
When enabled, the Magic Packet detection mode allows the triggering of the nINT or nPME pin when
a Magic Packet frame is received. A Magic Packet is a frame addressed to the device - either a unicast
to the programmed address, or a broadcast - which contains the pattern 48’h FF_FF_FF_FF_FF_FF
after the destination and source address field, followed by 16 repetitions of the desired MAC address
(loaded into the MAC Receive Address A Register (RX_ADDRA), MAC Receive Address B Register
(RX_ADDRB), and MAC Receive Address C Register (RX_ADDRC)) without any breaks or
interruptions. In case of a break in the 16 address repetitions, the logic scans for the 48’h
FF_FF_FF_FF_FF_FF pattern again in the incoming frame. The 16 repetitions may be anywhere in
the frame but must be preceded by the synchronization stream. The frame must also pass the FCS
check and packet length checking.
As an example, if the desired address is 00h 11h 22h 33h 44h 55h, then the logic scans for the
following data sequence in an Ethernet frame:
Destination Address Source Address ……………FF FF FF FF FF FF
00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55
00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55
00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55
00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55
…FCS
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As an example, the Host system must perform the following steps to enable the device to assert nINT
on detection of a Magic Packet WoL event:
1. Set the desired MAC address to cause the wake event in the MAC Receive Address A Register
(RX_ADDRA), MAC Receive Address B Register (RX_ADDRB), and MAC Receive Address C
Register (RX_ADDRC).
2. Set the Magic Packet Enable (MPEN) bit of the Wakeup Control and Status Register (WUCSR) to
enable Magic Packet detection.
3. Set bit 8 (WoL event indicator) in the Interrupt Mask Register to enable WoL events to trigger
assertion of the nINT interrupt pin.
When a match is triggered, the nINT interrupt pin will be asserted, bit 8 of the Interrupt Source Flag
Register will be set, and the Magic Packet Received (MPR) bit of the Wakeup Control and Status
Register (WUCSR) will be set.
Note: Alternatively, the LED1/nINT/nPME, LED2/nINT/nPME, or RXD2/nPME pin can be used to
indicate a WoL event. Refer to Section 3.8.4, "Wake on LAN (WoL)" for additional information.
3.8.4.4
Wakeup Frame Detection
When enabled, the Wakeup Frame detection mode allows the triggering of the nINT or nPME pin when
a pre-programmed Wakeup Frame is received. Wakeup Frame detection provides a way for system
designers to detect a customized pattern within a packet via a programmable wake-up frame filter. The
filter has a 128-bit byte mask that indicates which bytes of the frame should be compared by the
detection logic. A CRC-16 is calculated over these bytes. The result is then compared with the filter’s
respective CRC-16 to determine if a match exists. When a wake-up pattern is received, the Remote
Wakeup Frame Received (WUFR) bit of the Wakeup Control and Status Register (WUCSR) is set.
If enabled, the filter can also include a comparison between the frame’s destination address and the
address specified in the MAC Receive Address A Register (RX_ADDRA), MAC Receive Address B
Register (RX_ADDRB), and MAC Receive Address C Register (RX_ADDRC). The specified address
can be a unicast or a multicast. If address matching is enabled, only the programmed unicast or
multicast address will be considered a match. Non-specific multicast addresses and the broadcast
address can be separately enabled. The address matching results are logically OR’d (i.e., specific
address match result OR any multicast result OR broadcast result).
Whether or not the filter is enabled and whether the destination address is checked is determined by
configuring the Wakeup Filter Configuration Register A (WUF_CFGA). Before enabling the filter, the
application program must provide the detection logic with the sample frame and corresponding byte
mask. This information is provided by writing the Wakeup Filter Configuration Register A
(WUF_CFGA), Wakeup Filter Configuration Register B (WUF_CFGB), and Wakeup Filter Byte Mask
Registers (WUF_MASK). The starting offset within the frame and the expected CRC-16 for the filter is
determined by the Filter Pattern Offset and Filter CRC-16 fields, respectively.
If remote wakeup mode is enabled, the remote wakeup function checks each frame against the filter
and recognizes the frame as a remote wakeup frame if it passes the filter’s address filtering and CRC
value match.
The pattern offset defines the location of the first byte that should be checked in the frame. The byte
mask is a 128-bit field that specifies whether or not each of the 128 contiguous bytes within the frame,
beginning with the pattern offset, should be checked. If bit j in the byte mask is set, the detection logic
checks the byte (pattern offset + j) in the frame, otherwise byte (pattern offset + j) is ignored.
At the completion of the CRC-16 checking process, the CRC-16 calculated using the pattern offset and
byte mask is compared to the expected CRC-16 value associated with the filter. If a match occurs, a
remote wake-up event is signaled. The frame must also pass the FCS check and packet length
checking.
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Table 3.8 indicates the cases that produce a wake-up event. All other cases do not generate a wakeup event.
Table 3.8 Wakeup Generation Cases
FILTER
ENABLED
FRAME
TYPE
CRC
MATCHES
ADDRESS
MATCH
ENABLED
ANY
MCAST
ENABLED
BCAST
ENABLED
FRAME
ADDRESS
MATCHES
Yes
Unicast
Yes
No
X
X
X
Yes
Unicast
Yes
Yes
X
X
Yes
Yes
Multicast
Yes
X
Yes
X
X
Yes
Multicast
Yes
Yes
No
X
Yes
Yes
Broadcast
Yes
X
X
Yes
X
As an example, the Host system must perform the following steps to enable the device to assert nINT
on detection of a Wakeup Frame WoL event:
Declare Pattern:
1. Update the Wakeup Filter Byte Mask Registers (WUF_MASK) to indicate the valid bytes to match.
2. Calculate the CRC-16 value of valid bytes offline and update the Wakeup Filter Configuration
Register B (WUF_CFGB). CRC-16 is calculated as follows:
At the start of a frame, CRC-16 is initialized with the value FFFFh. CRC-16 is updated when the
pattern offset and mask indicate the received byte is part of the checksum calculation. The following
algorithm is used to update the CRC-16 at that time:
Let:
^ denote the exclusive or operator.
Data [7:0] be the received data byte to be included in the checksum.
CRC[15:0] contain the calculated CRC-16 checksum.
F0 … F7 be intermediate results, calculated when a data byte is determined to be part of the
CRC-16.
Calculate:
F0 = CRC[15] ^ Data[0]
F1 = CRC[14] ^ F0 ^ Data[1]
F2 = CRC[13] ^ F1 ^ Data[2]
F3 = CRC[12] ^ F2 ^ Data[3]
F4 = CRC[11] ^ F3 ^ Data[4]
F5 = CRC[10] ^ F4 ^ Data[5]
F6 = CRC[09] ^ F5 ^ Data[6]
F7 = CRC[08] ^ F6 ^ Data[7]
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The CRC-32 is updated as follows:
CRC[15] = CRC[7] ^ F7
CRC[14] = CRC[6]
CRC[13] = CRC[5]
CRC[12] = CRC[4]
CRC[11] = CRC[3]
CRC[10] = CRC[2]
CRC[9] = CRC[1] ^ F0
CRC[8] = CRC[0] ^ F1
CRC[7] = F0 ^ F2
CRC[6] = F1 ^ F3
CRC[5] = F2 ^ F4
CRC[4] = F3 ^ F5
CRC[3] = F4 ^ F6
CRC[2] = F5 ^ F7
CRC[1] = F6
CRC[0] = F7
3. Determine the offset pattern with offset 0 being the first byte of the destination address. Update
the offset in the Filter Pattern Offset field of the Wakeup Filter Configuration Register A
(WUF_CFGA).
Determine Address Matching Conditions:
4. Determine the address matching scheme based on Table 3.8 and update the Filter Broadcast
Enable, Filter Any Multicast Enable, and Address Match Enable bits of the Wakeup Filter
Configuration Register A (WUF_CFGA) accordingly.
5. If necessary (see step 4), set the desired MAC address to cause the wake event in the MAC
Receive Address A Register (RX_ADDRA), MAC Receive Address B Register (RX_ADDRB), and
MAC Receive Address C Register (RX_ADDRC).
6. Set the Filter Enable bit of the Wakeup Filter Configuration Register A (WUF_CFGA) to enable the
filter.
Enable Wakeup Frame Detection:
7. Set the Wakeup Frame Enable (WUEN) bit of the Wakeup Control and Status Register (WUCSR)
to enable Wakeup Frame detection.
8. Set bit 8 (WoL event indicator) in the Interrupt Mask Register to enable WoL events to trigger
assertion of the nINT interrupt pin.
When a match is triggered, the nINT interrupt pin will be asserted and the Remote Wakeup Frame
Received (WUFR) bit of the Wakeup Control and Status Register (WUCSR) will be set. To provide
additional visibility to software, the Filter Triggered bit of the Wakeup Filter Configuration Register A
(WUF_CFGA) will be set.
Note: Alternatively, the LED1/nINT/nPME, LED2/nINT/nPME, or RXD2/nPME pin can be used to
indicate a WoL event. Refer to Section 3.8.4, "Wake on LAN (WoL)" for additional information.
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3.8.5
Energy Efficient Ethernet
The device supports IEEE 802.3az Energy Efficient Ethernet (EEE). The EEE functionality is
enabled/disabled via the PHY Energy Efficient Ethernet Enable (PHYEEEEN) bit of the EDPD NLP /
Crossover Time / EEE Configuration Register. Energy Efficient Ethernet is disabled by default. In order
for EEE to be utilized, the following conditions must be met:
The device must configured in MII mode (RMIISEL configuration strap low)
The nINT/TXER/TXD4 pin must be configured as TXER/TXD4 (nINTSEL configuration strap low)
EEE functionality must be enabled via the PHY Energy Efficient Ethernet Enable (PHYEEEEN) bit
of the EDPD NLP / Crossover Time / EEE Configuration Register
The 100BASE-TX EEE bit of the MMD EEE Advertisement Register must be set
The selected MAC and link-partner must support and be configured for EEE operation
The device and link-partner must link in 100BASE-TX full-duplex mode
The value of the PHY Energy Efficient Ethernet Enable (PHYEEEEN) bit affects the default values of
the following register bits:
100BASE-TX EEE bit of the MMD EEE Capability Register
100BASE-TX EEE bit of the MMD EEE Advertisement Register
Note: EEE cannot be used in RMII mode.
Note: Due to the multiplexing of nINT and TXER on the same pin, when EEE and WoL are both
enabled, nINT and/or nPME must be multiplexed on LED1 and/or LED2. Refer to Section 3.8.1,
"LEDs," on page 43 and Section 3.8.4, "Wake on LAN (WoL)," on page 48 for additional
information.
3.8.6
Isolate Mode
The device data paths may be electrically isolated from the MII/RMII interface by setting the Isolate bit
of the Basic Control Register to “1”. In isolation mode, the transceiver does not respond to the TXD,
TXEN and TXER inputs, but does respond to management transactions.
Isolation provides a means for multiple transceivers to be connected to the same MII/RMII interface
without contention. By default, the transceiver is not isolated (on power-up (Isolate = 0).
3.8.7
Resets
The device provides two forms of reset: hardware and software. The device registers are reset by both
hardware and software resets. Select register bits, indicated as “NASR” in the register definitions, are
not cleared by a software reset. The registers are not reset by the power-down modes described in
Section 3.8.3.
Note: For the first 16 µs after coming out of reset, the MII/RMII interface will run at 2.5 MHz. After
this time, it will switch to 25 MHz if auto-negotiation is enabled.
3.8.7.1
Hardware Reset
A hardware reset is asserted by driving the nRST input pin low. When driven, nRST should be held
low for the minimum time detailed in Section 5.6.2, "Power-On nRST & Configuration Strap Timing,"
on page 130 to ensure a proper transceiver reset. During a hardware reset, an external clock must be
supplied to the XTAL1/CLKIN signal.
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Note: A hardware reset (nRST assertion) is required following power-up. Refer to Section 5.6.2,
"Power-On nRST & Configuration Strap Timing," on page 130 for additional information.
3.8.7.2
Software Reset
A Software reset is activated by setting the Soft Reset bit of the Basic Control Register to “1”. All
registers bits, except those indicated as “NASR” in the register definitions, are cleared by a Software
reset. The Soft Reset bit is self-clearing. Per the IEEE 802.3u standard, clause 22 (22.2.4.1.1) the reset
process will be completed within 0.5 s from the setting of this bit.
3.8.8
Carrier Sense
The carrier sense (CRS) is output on the CRS pin in MII mode, and the CRS_DV pin in RMII mode.
CRS is a signal defined by the MII specification in the IEEE 802.3u standard. The device asserts CRS
based only on receive activity whenever the transceiver is either in repeater mode or full-duplex mode.
Otherwise the transceiver asserts CRS based on either transmit or receive activity.
The carrier sense logic uses the encoded, unscrambled data to determine carrier activity status. It
activates carrier sense with the detection of 2 non-contiguous zeros within any 10 bit span. Carrier
sense terminates if a span of 10 consecutive ones is detected before a /J/K/ Start-of Stream Delimiter
pair. If an SSD pair is detected, carrier sense is asserted until either /T/R/ End–of-Stream Delimiter
pair or a pair of IDLE symbols is detected. Carrier is negated after the /T/ symbol or the first IDLE. If
/T/ is not followed by /R/, then carrier is maintained. Carrier is treated similarly for IDLE followed by
some non-IDLE symbol.
3.8.9
Collision Detect
A collision is the occurrence of simultaneous transmit and receive operations. The COL output is
asserted to indicate that a collision has been detected. COL remains active for the duration of the
collision. COL is changed asynchronously to both RXCLK and TXCLK. The COL output becomes
inactive during full duplex mode.
The COL may be tested by setting the Collision Test bit of the Basic Control Register to “1”. This
enables the collision test. COL will be asserted within 512 bit times of TXEN rising and will be deasserted within 4 bit times of TXEN falling.
3.8.10
Link Integrity Test
The device performs the link integrity test as outlined in the IEEE 802.3u (clause 24-15) Link Monitor
state diagram. The link status is multiplexed with the 10 Mbps link status to form the Link Status bit in
the Basic Status Register and to drive the LINK LED (LED1).
The DSP indicates a valid MLT-3 waveform present on the RXP and RXN signals as defined by the
ANSI X3.263 TP-PMD standard, to the Link Monitor state-machine, using the internal DATA_VALID
signal. When DATA_VALID is asserted, the control logic moves into a Link-Ready state and waits for
an enable from the auto-negotiation block. When received, the Link-Up state is entered, and the
Transmit and Receive logic blocks become active. Should auto-negotiation be disabled, the link
integrity logic moves immediately to the Link-Up state when the DATA_VALID is asserted.
To allow the line to stabilize, the link integrity logic will wait a minimum of 330 ms from the time
DATA_VALID is asserted until the Link-Ready state is entered. Should the DATA_VALID input be
negated at any time, this logic will immediately negate the Link signal and enter the Link-Down state.
When the 10/100 digital block is in 10BASE-T mode, the link status is derived from the 10BASE-T
receiver logic.
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3.8.11
Cable Diagnostics
The LAN8740A/LAN8740Ai provides cable diagnostics which allow for open/short and length detection
of the Ethernet cable. The cable diagnostics consist of two primary modes of operation:
Time Domain Reflectometry (TDR) Cable Diagnostics
TDR cable diagnostics enable the detection of open or shorted cabling on the TX or RX pair, as
well as cable length estimation to the open/short fault.
Matched Cable Diagnostics
Matched cable diagnostics enable cable length estimation on 100 Mbps-linked cables.
Refer to the following sub-sections for details on proper operation of each cable diagnostics mode.
3.8.11.1
Time Domain Reflectometry (TDR) Cable Diagnostics
The LAN8740A/LAN8740Ai provides TDR cable diagnostics which enable the detection of open or
shorted cabling on the TX or RX pair, as well as cable length estimation to the open/short fault. To
utilize the TDR cable diagnostics, Auto-MDIX and Auto Negotiation must be disabled, and the
LAN8740A/LAN8740Ai device must be forced to 100 Mb full-duplex mode. These actions must be
performed before setting the TDR Enable bit in the TDR Control/Status Register. With Auto-MDIX
disabled, the TDR will test the TX or RX pair selected by register bit 27.15 (AMDIXCTRL). Proper cable
testing should include a test of each pair. When TDR testing is complete, prior register settings may
be restored. Figure 3.13 provides a flow diagram of proper TDR usage.
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Start
Disable ANEG and Force 100Mb FullDuplex
Write PHY Reg 0: 0x2100
Disable AMDIX and Force MDI (or MDIX)
Write PHY Reg 27: 0x8000 (MDI)
- OR Write PHY Reg 27: 0xA000 (MDIX)
Enable TDR
Write PHY Reg 25: 0x8000
Check TDR Control/Status Register
Read PHY Reg 25: 0x8000
NO
Reg 25.8 == 0
TDR Channel Status Complete?
YES
Reg 25.8 == 1
Save:
TDR Channel Type (Reg 25.10:9)
TDR Channel Length (Reg 25.7:0)
Repeat Testing
in MDIX Mode
MDIX Case Tested?
YES
Done
Figure 3.13 TDR Usage Flow Diagram
The TDR operates by transmitting pulses on the selected twisted pair within the Ethernet cable (TX in
MDI mode, RX in MDIX mode). If the pair being tested is open or shorted, the resulting impedance
discontinuity results in a reflected signal that can be detected by the LAN8740A/LAN8740Ai. The
LAN8740A/LAN8740Ai measures the time between the transmitted signal and received reflection and
indicates the results in the TDR Channel Length field of the TDR Control/Status Register. The TDR
Channel Length field indicates the “electrical” length of the cable, and can be multiplied by the
appropriate propagation constant in Table 3.9 to determine the approximate physical distance to the
fault.
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Note: The TDR function is typically used when the link is inoperable. However, an active link will drop
when operating the TDR.
Since the TDR relies on the reflected signal of an improperly terminated cable, there are several
factors that can affect the accuracy of the physical length estimate. These include:
1. Cable Type (CAT 5, CAT5e, CAT6): The electrical length of each cable type is slightly different
due to the twists-per-meter of the internal signal pairs and differences in signal propagation speeds.
If the cable type is known, the length estimate can be calculated more accurately by using the
propagation constant appropriate for the cable type (see Table 3.9). In many real-world applications
the cable type is unknown, or may be a mix of different cable types and lengths. In this case, use
the propagation constant for the “unknown” cable type.
2. TX and RX Pair: For each cable type, the EIA standards specify different twist rates (twists-permeter) for each signal pair within the Ethernet cable. This results in different measurements for the
RX and TX pair.
3. Actual Cable Length: The difference between the estimated cable length and actual cable length
grows as the physical cable length increases, with the most accurate results at less than
approximately 100 m.
4. Open/Short Case: The Open and Shorted cases will return different TDR Channel Length values
(electrical lengths) for the same physical distance to the fault. Compensation for this is achieved
by using different propagation constants to calculate the physical length of the cable.
For the Open case, the estimated distance to the fault can be calculated as follows:
Distance to Open fault in meters ≅ TDR Channel Length * POPEN
Where: POPEN is the propagation constant selected from Table 3.9
For the Shorted case, the estimated distance to the fault can be calculated as follows:
Distance to Open fault in meters ≅ TDR Channel Length * PSHORT
Where: PSHORT is the propagation constant selected from Table 3.9
Table 3.9 TDR Propagation Constants
CABLE TYPE
TDR PROPAGATION
CONSTANT
UNKNOWN
CAT 6
CAT 5E
CAT 5
POPEN
0.769
0.745
0.76
0.85
PSHORT
0.793
0.759
0.788
0.873
The typical cable length measurement margin of error for Open and Shorted cases is dependent on
the selected cable type and the distance of the open/short from the device. Table 3.10 and Table 3.11
detail the typical measurement error for Open and Shorted cases, respectively.
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Table 3.10 Typical Measurement Error for Open Cable (+/- Meters)
PHYSICAL DISTANCE
TO FAULT
SELECTED PROPAGATION CONSTANT
POPEN =
Unknown
POPEN =
CAT 6
CAT 6 Cable, 0-100 m
9
6
CAT 5E Cable, 0-100 m
5
CAT 5 Cable, 0-100 m
13
CAT 6 Cable, 101-160 m
14
CAT 5E Cable, 101-160 m
8
CAT 5 Cable, 101-160 m
20
POPEN =
CAT 5E
POPEN =
CAT 5
5
3
6
6
6
Table 3.11 Typical Measurement Error for Shorted Cable (+/- Meters)
PHYSICAL DISTANCE
TO FAULT
SELECTED PROPAGATION CONSTANT
PSHORT =
Unknown
PSHORT =
CAT 6
CAT 6 Cable, 0-100 m
8
5
CAT 5E Cable, 0-100 m
5
CAT 5 Cable, 0-100 m
11
CAT 6 Cable, 101-160 m
14
CAT 5E Cable, 101-160 m
7
CAT 5 Cable, 101-160 m
11
SMSC LAN8740A/LAN8740Ai
PSHORT =
CAT 5E
PSHORT =
CAT 5
5
2
6
6
3
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3.8.11.2
Matched Cable Diagnostics
Matched cable diagnostics enable cable length estimation on 100 Mbps-linked cables of up to 120
meters. If there is an active 100 Mb link, the approximate distance to the link partner can be estimated
using the Cable Length Register. If the cable is properly terminated, but there is no active 100 Mb link
(the link partner is disabled, nonfunctional, the link is at 10 Mb, etc.), the cable length cannot be
estimated and the Cable Length Register should be ignored. The estimated distance to the link partner
can be determined via the Cable Length (CBLN) lookup table provided in Table 3.12. The typical cable
length measurement margin of error for a matched cable case is +/- 20 m. The matched cable length
margin of error is consistent for all cable types from 0 to 120 m.
Table 3.12 Match Case Estimated Cable Length (CBLN) Lookup Table
CBLN FIELD VALUE
ESTIMATED CABLE LENGTH
0-3
0
4
6
5
17
6
27
7
38
8
49
9
59
10
70
11
81
12
91
13
102
14
113
15
123
Note: For a properly terminated cable (Match case), there is no reflected signal. In this case, the TDR
Channel Length field is invalid and should be ignored.
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3.8.12
Loopback Operation
The device may be configured for near-end loopback and far loopback. These loopback modes are
detailed in the following subsections.
3.8.12.1
Near-end Loopback
Near-end loopback mode sends the digital transmit data back out the receive data signals for testing
purposes, as indicated by the blue arrows in Figure 3.14. The near-end loopback mode is enabled by
setting the Loopback bit of the Basic Control Register to “1”. A large percentage of the digital circuitry
is operational in near-end loopback mode because data is routed through the PCS and PMA layers
into the PMD sublayer before it is looped back. The COL signal will be inactive in this mode, unless
Collision Test is enabled in the Basic Control Register. The transmitters are powered down regardless
of the state of TXEN. Refer to Section 5.6.3.1, "100 Mbps Internal Loopback MII Timing," on page 133
for additional loopback timing information.
TXD
10/100
Ethernet
MAC
RXD
Digital
Analog
X
TX
X
RX
XFMR
CAT-5
SMSC
Ethernet Transceiver
Figure 3.14 Near-end Loopback Block Diagram
3.8.12.2
Far Loopback
Far loopback is a special test mode for MDI (analog) loopback as indicated by the blue arrows in
Figure 3.15. The far loopback mode is enabled by setting the FARLOOPBACK bit of the Mode
Control/Status Register to “1”. In this mode, data that is received from the link partner on the MDI is
looped back out to the link partner. The digital interface signals on the local MAC interface are isolated.
Note: This special test mode is only available when operating in RMII mode.
Far-end system
10/100
Ethernet
MAC
TXD
RXD
X
TX
X
RX
Digital
XFMR
CAT-5
Link
Partner
Analog
SMSC
Ethernet Transceiver
Figure 3.15 Far Loopback Block Diagram
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3.8.12.3
Connector Loopback
The device maintains reliable transmission over very short cables and can be tested in a connector
loopback as shown in Figure 3.16. An RJ45 loopback cable can be used to route the transmit signals
from the output of the transformer back to the receiver inputs. The loopback works at both 10 and
100 Mbps.
10/100
Ethernet
MAC
TXD
1
2
3
4
5
6
7
8
TX
RXD
RX
Digital
XFMR
Analog
SMSC
RJ45 Loopback Cable.
Created by connecting pin 1 to pin 3
and connecting pin 2 to pin 6.
Ethernet Transceiver
Figure 3.16 Connector Loopback Block Diagram
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3.9
Application Diagrams
This section provides typical application diagrams for the following:
3.9.1
Simplified System Level Application Diagram
Power Supply Diagram (1.2 V Supplied by Internal Regulator)
Power Supply Diagram (1.2 V Supplied by External Source)
Twisted-Pair Interface Diagram (Single Power Supply)
Twisted-Pair Interface Diagram (Dual Power Supplies)
Simplified System Level Application Diagram
LAN8740A/LAN8740Ai
10/100 PHY
32-QFN
MII
MDIO
MII
MDC
nINT
Mag
TXD[3:0]
4
RJ45
TXP
TXN
TXCLK
TXER
TXEN
RXP
RXN
RXD[3:0]
4
RXCLK
RXDV
XTAL1/CLKIN
25 MHz
LED[2:1]
XTAL2
2
nRST
Interface
Figure 3.17 Simplified System Level Application Diagram
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3.9.2
Power Supply Diagram (1.2 V Supplied by Internal Regulator)
LAN8740A/LAN8740Ai
32-QFN
Ch.2: 3.3 V
Circuitry
Core Logic
VDDCR
OUT
470 pF
1 uF
VDDDIO
Supply
1.8 - 3.3 V
Internal
Regulator
IN
Ch.1: 3.3 V
Circuitry
VDDIO
CF
Power
Supply
3.3 V
VDD2A
CBYPASS
VDD1A
CBYPASS
CBYPASS
RBIAS
LED1/
REGOFF
12.1k
VSS
~270 Ohm
Figure 3.18 Power Supply Diagram (1.2 V Supplied by Internal Regulator)
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3.9.3
Power Supply Diagram (1.2 V Supplied by External Source)
LAN8740A/LAN8740Ai
32-QFN
Ch.2: 3.3 V
Circuitry
Core Logic
VDDCR
Supply
1.2 V
VDDCR
OUT
470 pF
1 uF
VDDDIO
Supply
1.8 - 3.3 V
Internal
Regulator
VDD2A
IN
(Disabled)
CBYPASS
VDD1A
Ch.1: 3.3 V
Circuitry
VDDIO
CF
Power
Supply
3.3 V
CBYPASS
CBYPASS
RBIAS
LED1/
REGOFF
12.1k
VSS
~270 Ohm
10k
Figure 3.19 Power Supply Diagram (1.2 V Supplied by External Source)
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3.9.4
Twisted-Pair Interface Diagram (Single Power Supply)
LAN8740A/LAN8740Ai
32-QFN
Power
Supply
3.3 V
Ferrite
Bead
49.9 Ohm Resistors
VDD2A
CBYPASS
VDD1A
CBYPASS
Magnetics
RJ45
TXP
1
2
3
4
5
6
7
8
75 Ohm
TXN
RXP
75 Ohm
RXN
1000 pF
3 kV
CBYPASS
Figure 3.20 Twisted-Pair Interface Diagram (Single Power Supply)
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3.9.5
Twisted-Pair Interface Diagram (Dual Power Supplies)
LAN8740A/LAN8740Ai
32-QFN
Power
Supply
3.3 V
Power
Supply
2.5 V - 3.3 V
49.9 Ohm Resistors
VDD2A
CBYPASS
VDD1A
CBYPASS
Magnetics
RJ45
TXP
1
2
3
4
5
6
7
8
75 Ohm
TXN
RXP
75 Ohm
RXN
1000 pF
3 kV
CBYPASS
Figure 3.21 Twisted-Pair Interface Diagram (Dual Power Supplies)
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Chapter 4 Register Descriptions
This chapter describes the various Control and Status Registers (CSRs) and MDIO Manageable
Device (MMD) Registers. The CSRs follow the IEEE 802.3 (clause 22.2.4) management register set.
The MMD registers adhere to the IEEE 802.3-2008 45.2 MDIO Interface Registers specification. All
functionality and bit definitions comply with these standards. The IEEE 802.3 specified register index
(in decimal) is included with each CSR definition, allowing for addressing of these registers via the
Serial Management Interface (SMI) protocol. MMD registers are accessed indirectly via the MMD
Access Control Register and MMD Access Address/Data Register CSRs.
4.1
Register Nomenclature
Table 4.1 describes the register bit attribute notation used throughout this document.
Table 4.1 Register Bit Types
REGISTER BIT TYPE
NOTATION
REGISTER BIT DESCRIPTION
R
Read: A register or bit with this attribute can be read.
W
Write: A register or bit with this attribute can be written.
RO
Read only: Writes have no effect.
WO
Write only: If a register or bit is write-only, reads will return unspecified data.
WC
Write One to Clear: Writing a one clears the value. Writing a zero has no effect
WAC
Write Anything to Clear: Writing anything clears the value.
RC
Read to Clear: Contents is cleared after the read. Writes have no effect.
LL
Latch Low: Clear on read of register.
LH
Latch High: Clear on read of register.
SC
Self-Clearing: Contents are self-cleared after the being set. Writes of zero have no
effect. Contents can be read.
SS
Self-Setting: Contents are self-setting after being cleared. Writes of one have no
effect. Contents can be read.
RO/LH
Read Only, Latch High: Bits with this attribute will stay high until the bit is read. After
it is read, the bit will either remain high if the high condition remains, or will go low if
the high condition has been removed. If the bit has not been read, the bit will remain
high regardless of a change to the high condition. This mode is used in some Ethernet
PHY registers.
NASR
Not Affected by Software Reset. The state of NASR bits do not change on assertion
of a software reset.
RESERVED
Reserved Field: Reserved fields must be written with zeros to ensure future
compatibility. The value of reserved bits is not guaranteed on a read.
Many of these register bit notations can be combined. Some examples of this are shown below:
R/W: Can be written. Will return current setting on a read.
R/WAC: Will return current setting on a read. Writing anything clears the bit.
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4.2
Control and Status Registers
Table 4.2 provides a list of supported registers. Register details, including bit definitions, are provided
in the proceeding subsections.
Table 4.2 SMI Register Map
REGISTER INDEX
(DECIMAL)
REGISTER NAME
GROUP
0
Basic Control Register
Basic
1
Basic Status Register
Basic
2
PHY Identifier 1 Register
Extended
3
PHY Identifier 2 Register
Extended
4
Auto Negotiation Advertisement Register
Extended
5
Auto Negotiation Link Partner Ability Register
Extended
6
Auto Negotiation Expansion Register
Extended
7
Auto Negotiation Next Page TX Register
Extended
8
Auto Negotiation Next Page RX Register
Extended
13
MMD Access Control Register
Extended
14
MMD Access Address/Data Register
Extended
16
EDPD NLP / Crossover Time / EEE Configuration Register
Vendor-specific
17
Mode Control/Status Register
Vendor-specific
18
Special Modes Register
Vendor-specific
24
TDR Patterns/Delay Control Register
Vendor-specific
25
TDR Control/Status Register
Vendor-specific
26
Symbol Error Counter Register
Vendor-specific
27
Special Control/Status Indications Register
Vendor-specific
28
Cable Length Register
Vendor-specific
29
Interrupt Source Flag Register
Vendor-specific
30
Interrupt Mask Register
Vendor-specific
31
PHY Special Control/Status Register
Vendor-specific
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4.2.1
Basic Control Register
Index (In Decimal):
0
Size:
16 bits
BITS
DESCRIPTION
TYPE
DEFAULT
15
Soft Reset
1 = Software reset. Bit is self-clearing. When setting this bit do not set other
bits in this register.
R/W
SC
0b
Note:
The configuration (as described in Section 3.7.2, "MODE[2:0]:
Mode Configuration," on page 40) is set from the register bit values,
and not from the mode pins.
14
Loopback
0 = Normal operation
1 = Loopback mode
R/W
0b
13
Speed Select
0 = 10 Mbps
1 = 100 Mbps
R/W
Note 4.1
Note:
Ignored if auto-negotiation is enabled (0.12 = 1).
12
Auto-Negotiation Enable
0 = Disable auto-negotiate process
1 = Enable auto-negotiate process (overrides 0.13 and 0.8)
R/W
Note 4.1
11
Power Down
0 = Normal operation
1 = General power down mode
R/W
0b
10
Isolate
0 = Normal operation
1 = Electrical isolation of PHY from the MII/RMII
R/W
0b
9
Restart Auto-Negotiate
0 = Normal operation
1 = Restart auto-negotiate process
R/W
SC
0b
R/W
Note 4.1
Collision Test
0 = Disable COL test
1 = Enable COL test
R/W
0b
RESERVED
RO
-
Note:
8
Duplex Mode
0 = Half duplex
1 = Full duplex
Note:
7
6:0
Bit is self-clearing.
Ignored if Auto-Negotiation is enabled (0.12 = 1).
Note 4.1
Revision 1.1 (05-10-13)
The default value of this bit is determined by the MODE[2:0] configuration straps. Refer to
Section 3.7.2, "MODE[2:0]: Mode Configuration," on page 40 for additional information.
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4.2.2
Basic Status Register
Index (In Decimal):
BITS
1
Size:
DESCRIPTION
16 bits
TYPE
DEFAULT
15
100BASE-T4
0 = No T4 ability
1 = T4 able
RO
0b
14
100BASE-TX Full Duplex
0 = No TX full duplex ability
1 = TX with full duplex
RO
1b
13
100BASE-TX Half Duplex
0 = No TX half duplex ability
1 = TX with half duplex
RO
1b
12
10BASE-T Full Duplex
0 = No 10 Mbps with full duplex ability
1 = 10 Mbps with full duplex
RO
1b
11
10BASE-T Half Duplex
0 = No 10 Mbps with half duplex ability
1 = 10 Mbps with half duplex
RO
1b
10
100BASE-T2 Full Duplex
0 = PHY is not able to perform full duplex 100BASE-T2
1 = PHY is able to perform full duplex 100BASE-T2
RO
0b
9
100BASE-T2 Half Duplex
0 = PHY is not able to perform half duplex 100BASE-T2
1 = PHY is able to perform half duplex 100BASE-T2
RO
0b
8
Extended Status
0 = No extended status information in register 15
1 = Extended status information in register 15
RO
0b
RESERVED
RO
-
5
Auto-Negotiate Complete
0 = Auto-negotiate process not completed
1 = Auto-negotiate process completed
RO
0b
4
Remote Fault
1 = Remote fault condition detected
0 = No remote fault
RO/LH
0b
3
Auto-Negotiate Ability
0 = Unable to perform auto-negotiation function
1 = Able to perform auto-negotiation function
RO
1b
2
Link Status
0 = Link is down.
1 = Link is up.
RO/LL
0b
1
Jabber Detect
0 = No jabber condition detected.
1 = Jabber condition detected.
RO/LH
0b
7:6
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BITS
0
DESCRIPTION
Extended Capabilities
0 = Does not support extended capabilities registers
1 = Supports extended capabilities registers
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TYPE
DEFAULT
RO
1b
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4.2.3
PHY Identifier 1 Register
Index (In Decimal):
BITS
15:0
2
Size:
16 bits
DESCRIPTION
PHY ID Number
Assigned to the 3rd through 18th bits of the Organizationally Unique
Identifier (OUI), respectively.
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TYPE
DEFAULT
R/W
0007h
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4.2.4
PHY Identifier 2 Register
Index (In Decimal):
BITS
15:10
3
Size:
DESCRIPTION
16 bits
TYPE
PHY ID Number
Assigned to the 19th through 24th bits of the OUI.
R/W
9:4
Model Number
Six-bit manufacturer’s model number
R/W
3:0
Revision Number
Four-bit manufacturer’s revision number
R/W
DEFAULT
C110h
Note: The default value of the Revision Number field may vary dependant on the silicon revision
number.
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SMSC LAN8740A/LAN8740Ai
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.2.5
Auto Negotiation Advertisement Register
Index (In Decimal):
BITS
4
Size:
16 bits
DESCRIPTION
TYPE
DEFAULT
15
Next Page
0 = No next page ability
1 = Next page capable
R/W
0b
14
RESERVED
RO
-
13
Remote Fault
0 = No remote fault
1 = Remote fault detected
R/W
0b
12
RESERVED
RO
-
Pause Operation
00 = No PAUSE
01 = Symmetric PAUSE
10 = Asymmetric PAUSE toward link partner
11 = Advertise support for both Symmetric PAUSE and Asymmetric PAUSE
toward local device
R/W
00b
11:10
Note:
When both symmetric PAUSE and asymmetric PAUSE are set, the
device will only be configured to, at most, one of the two settings
upon auto-negotiation completion.
9
RESERVED
RO
-
8
100BASE-TX Full Duplex
0 = No TX full duplex ability
1 = TX with full duplex
R/W
Note 4.2
7
100BASE-TX
0 = No TX ability
1 = TX able
R/W
1b
6
10BASE-T Full Duplex
0 = No 10 Mbps with full duplex ability
1 = 10 Mbps with full duplex
R/W
Note 4.2
5
10BASE-T
0 = No 10 Mbps ability
1 = 10 Mbps able
R/W
Note 4.2
Selector Field
00001 = IEEE 802.3
R/W
00001b
4:0
Note 4.2
The default value of this bit is determined by the MODE[2:0] configuration straps. Refer to
Section 3.7.2, "MODE[2:0]: Mode Configuration," on page 40 for additional information.
SMSC LAN8740A/LAN8740Ai
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.2.6
Auto Negotiation Link Partner Ability Register
Index (In Decimal):
BITS
5
Size:
16 bits
DESCRIPTION
TYPE
DEFAULT
15
Next Page
0 = No next page ability
1 = Next page capable
RO
0b
14
Acknowledge
0 = Link code word not yet received
1 = Link code word received from partner
RO
0b
13
Remote Fault
0 = No remote fault
1 = Remote fault detected
RO
0b
12
RESERVED
RO
-
Pause Operation
00 = No PAUSE supported by partner station
01 = Symmetric PAUSE supported by partner station
10 = Asymmetric PAUSE supported by partner station
11 = Both Symmetric PAUSE and Asymmetric PAUSE supported by partner
station
RO
00b
100BASE-T4
0 = No T4 ability
1 = T4 able
RO
0b
11:10
9
Note:
This device does not support T4 ability.
8
100BASE-TX Full Duplex
0 = No TX full duplex ability
1 = TX with full duplex
RO
0b
7
100BASE-TX
0 = No TX ability
1 = TX able
RO
0b
6
10BASE-T Full Duplex
0 = No 10 Mbps with full duplex ability
1 = 10 Mbps with full duplex
RO
0b
5
10BASE-T
0 = No 10 Mbps ability
1 = 10 Mbps able
RO
0b
Selector Field
00001 = IEEE 802.3
RO
00001b
4:0
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.2.7
Auto Negotiation Expansion Register
Index (In Decimal):
BITS
6
Size:
16 bits
TYPE
DEFAULT
RESERVED
RO
-
6
Receive Next Page Location Able
0 = Received next page storage location is not specified by bit 6.5
1 = Received next page storage location is specified by bit 6.5
RO
1b
5
Received Next Page Storage Location
0 = Link partner next pages are stored in the Auto Negotiation Link Partner
Ability Register (PHY register 5)
1 = Link partner next pages are stored in the Auto Negotiation Next Page
RX Register (PHY register 8)
RO
1b
4
Parallel Detection Fault
0 = No fault detected by parallel detection logic
1 = Fault detected by parallel detection logic
RO/LH
0b
3
Link Partner Next Page Able
0 = Link partner does not have next page ability.
1 = Link partner has next page ability.
RO
0b
2
Next Page Able
0 = Local device does not have next page ability.
1 = Local device has next page ability.
RO
1b
1
Page Received
0 = New page not yet received
1 = New page received
RO/LH
0b
0
Link Partner Auto-Negotiation Able
0 = Link partner does not have auto-negotiation ability.
1 = Link partner has auto-negotiation ability.
RO
0b
15:7
DESCRIPTION
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Revision 1.1 (05-10-13)
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.2.8
Auto Negotiation Next Page TX Register
Index (In Decimal):
BITS
7
Size:
DESCRIPTION
16 bits
TYPE
DEFAULT
15
Next Page
0 = No next page ability
1 = Next page capable
R/W
0b
14
RESERVED
RO
-
13
Message Page
0 = Unformatted page
1 = Message page
R/W
1b
12
Acknowledge 2
0 = Device cannot comply with message.
1 = Device will comply with message.
R/W
0b
11
Toggle
0 = Previous value was HIGH.
1 = Previous value was LOW.
RO
0b
Message Code
Message/Unformatted Code Field
R/W
000
0000
0001b
10:0
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.2.9
Auto Negotiation Next Page RX Register
Index (In Decimal):
BITS
8
Size:
DESCRIPTION
16 bits
TYPE
DEFAULT
15
Next Page
0 = No next page ability
1 = Next page capable
RO
0b
14
Acknowledge
0 = Link code word not yet received from partner
1 = Link code word received from partner
RO
0b
13
Message Page
0 = Unformatted page
1 = Message page
RO
0b
12
Acknowledge 2
0 = Device cannot comply with message.
1 = Device will comply with message.
RO
0b
11
Toggle
0 = Previous value was HIGH.
1 = Previous value was LOW.
RO
0b
Message Code
Message/Unformatted Code Field
RO
000
0000
0000b
10:0
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DATASHEET
Revision 1.1 (05-10-13)
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.2.10
MMD Access Control Register
Index (In Decimal):
13
Size:
16 bits
This register in conjunction with the MMD Access Address/Data Register provides indirect access to
the MDIO Manageable Device (MMD) registers. Refer to Section 4.3, "MDIO Manageable Device
(MMD) Registers," on page 93 for additional details.
BITS
DESCRIPTION
TYPE
DEFAULT
15:14
MMD Function
This field is used to select the desired MMD function:
00 = Address
01 = Data, no post increment
10 = RESERVED
11 = RESERVED
R/W
00b
13:5
RESERVED
RO
-
4:0
MMD Device Address (DEVAD)
This field is used to select the desired MMD device address.
(3 = PCS, 7 = auto-negotiation)
R/W
0h
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.2.11
MMD Access Address/Data Register
Index (In Decimal):
14
Size:
16 bits
This register in conjunction with the MMD Access Control Register provides indirect access to the
MDIO Manageable Device (MMD) registers. Refer to Section 4.3, "MDIO Manageable Device (MMD)
Registers," on page 93 for additional details.
BITS
DESCRIPTION
TYPE
DEFAULT
15:0
MMD Register Address/Data
If the MMD Function field of the MMD Access Control Register is “00”, this
field is used to indicate the MMD register address to read/write of the device
specified in the MMD Device Address (DEVAD) field. Otherwise, this register
is used to read/write data from/to the previously specified MMD address.
R/W
0000h
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Revision 1.1 (05-10-13)
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.2.12
EDPD NLP / Crossover Time / EEE Configuration Register
Index (In Decimal):
16
Size:
16 bits
BITS
DESCRIPTION
TYPE
DEFAULT
15
EDPD TX NLP Enable
When in Energy Detect Power-Down (EDPD) mode (EDPWRDOWN = 1),
this bit enables the transmission of single TX NLPs at the interval defined by
the EDPD TX NLP Interval Timer Select field.
0 = TX NLP disabled
1 = TX NLP enabled when in EDPD mode
R/W
NASR
0b
14:13
EDPD TX NLP Interval Timer Select
When in Energy Detect Power-Down (EDPD) mode (EDPWRDOWN = 1)
and EDPD TX NLP Enable is 1, this field defines the interval used to send
single TX NLPs.
00 = 1 second (default)
01 = 768 ms
10 = 512 ms
11 = 256 ms
R/W
NASR
00b
12
EDPD RX Single NLP Wake Enable
When in Energy Detect Power-Down (EDPD) mode (EDPWRDOWN = 1),
this bit enables waking the PHY on reception of a single RX NLP.
0 = RX NLP wake disabled
1 = TX NLP wake enabled when in EDPD mode
R/W
NASR
0b
EDPD RX NLP Max Interval Detect Select
When in Energy Detect Power-Down (EDPD) mode (EDPWRDOWN = 1)
and EDPD RX Single NLP Wake Enable is 0, this field defines the maximum
interval for detecting two RX NLPs to wake from EDPD mode
00 = 64 ms (default)
01 = 256 ms
10 = 512 ms
11 = 1 second
R/W
NASR
00b
RO
-
11:10
9:3
RESERVED
2
PHY Energy Efficient Ethernet Enable (PHYEEEEN)
When set, enables Energy Efficient Ethernet (EEE) operation in the PHY.
When cleared, EEE operation is disabled.
Refer to Section 3.8.5, "Energy Efficient Ethernet," on page 54 for additional
information.
R/W
NASR
0b
1
EDPD Extend Crossover
When in Energy Detect Power-Down (EDPD) mode (EDPWRDOWN = 1),
setting this bit to 1 extends the crossover time by 2976 ms.
0 = Crossover time extension disabled
1 = Crossover time extension enabled (2976 ms)
R/W
NASR
0b
0
Extend Manual 10/100 Auto-MDIX Crossover Time
When Auto-MIDX is enabled and the PHY is in manual 10BASE-T or
100BASE-TX mode, setting this bit to 1 extends the crossover time by 1984
ms to allow linking to an auto-negotiation link partner PHY.
0 = Crossover time extension disabled
1 = Crossover time extension enabled (1984 ms)
R/W
NASR
1b
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.2.13
Mode Control/Status Register
Index (In Decimal):
BITS
17
Size:
16 bits
TYPE
DEFAULT
RESERVED
RO
-
EDPWRDOWN
Enable the Energy Detect Power-Down (EDPD) mode:
0 = Energy Detect Power-Down is disabled.
1 = Energy Detect Power-Down is enabled.
R/W
0b
RESERVED
RO
-
FARLOOPBACK
Enables far loopback mode (i.e., all the received packets are sent back
simultaneously (in 100BASE-TX only)). This bit is only active in RMII mode.
This mode works even if the Isolate bit (0.10) is set.
0 = Far loopback mode is disabled.
1 = Far loopback mode is enabled.
Refer to Section 3.8.12.2, "Far Loopback," on page 61 for additional
information.
R/W
0b
RESERVED
RO
-
ALTINT
Alternate Interrupt Mode:
0 = Primary interrupt system enabled (Default)
1 = Alternate interrupt system enabled
Refer to Section 3.6, "Interrupt Management," on page 36 for additional
information.
R/W
0b
RESERVED
RO
-
1
ENERGYON
Indicates whether energy is detected. This bit transitions to “0” if no valid
energy is detected within 256 ms. It is reset to “1” by a hardware reset and
is unaffected by a software reset. Refer to Section 3.8.3.2, "Energy Detect
Power-Down (EDPD)," on page 48 for additional information.
RO
1b
0
RESERVED
R/W
0b
15:14
13
DESCRIPTION
Note:
12:10
9
8:7
6
5:2
When in EDPD mode, the device’s NLP characteristics can be
modified via the EDPD NLP / Crossover Time / EEE Configuration
Register.
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DATASHEET
Revision 1.1 (05-10-13)
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.2.14
Special Modes Register
Index (In Decimal):
BITS
18
Size:
16 bits
DESCRIPTION
TYPE
DEFAULT
15
RESERVED
RO
-
14
MIIMODE
Reflects the mode of the digital interface:
0 = MII mode
1 = RMII mode
RO
Note 4.3
13:8
RESERVED
RO
-
7:5
MODE
Transceiver mode of operation. Refer to Section 3.7.2, "MODE[2:0]: Mode
Configuration," on page 40 for additional details.
R/W
NASR
Note 4.4
4:0
PHYAD
PHY Address. The PHY Address is used for the SMI address and for
initialization of the Cipher (Scrambler) key. Refer to Section 3.7.1,
"PHYAD[2:0]: PHY Address Configuration," on page 39 for additional details.
R/W
NASR
Note 4.5
Note 4.3
The default value of this field is determined by the RMIISEL configuration strap. Refer to
Section 3.7.3, "RMIISEL: MII/RMII Mode Configuration," on page 41 for additional
information.
Note 4.4
The default value of this field is determined by the MODE[2:0] configuration straps. Refer
to Section 3.7.2, "MODE[2:0]: Mode Configuration," on page 40 for additional information.
Note 4.5
The default value of this field is determined by the PHYAD[0] configuration strap. Refer to
Section 3.7.1, "PHYAD[2:0]: PHY Address Configuration," on page 39 for additional
information.
Revision 1.1 (05-10-13)
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.2.15
TDR Patterns/Delay Control Register
Index (In Decimal):
24
Size:
16 bits
BITS
DESCRIPTION
TYPE
DEFAULT
15
TDR Delay In
0 = Line break time is 2 ms.
1 = The device uses TDR Line Break Counter to increase the line break time
before starting TDR.
R/W
NASR
0b
14:12
TDR Line Break Counter
When TDR Delay In is 1, this field specifies the increase in line break time
in increments of 256 ms, up to 2 seconds.
R/W
NASR
000b
11:6
TDR Pattern High
This field specifies the data pattern sent in TDR mode for the high cycle.
R/W
NASR
101110b
5:0
TDR Pattern Low
This field specifies the data pattern sent in TDR mode for the low cycle.
R/W
NASR
011101b
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.2.16
TDR Control/Status Register
Index (In Decimal):
BITS
15
Size:
16 bits
DESCRIPTION
TDR Enable
0 = TDR mode disabled
1 = TDR mode enabled
Note:
14
25
TYPE
DEFAULT
R/W
NASR
SC
0b
R/W
NASR
0b
RO
-
This bit self clears when TDR completes
(TDR Channel Status goes high)
TDR Analog to Digital Filter Enable
0 = TDR analog to digital filter disabled
1 = TDR analog to digital filter enabled (reduces noise spikes during TDR
pulses)
13:11
RESERVED
10:9
TDR Channel Cable Type
Indicates the cable type determined by the TDR test.
00 = Default
01 = Shorted cable condition
10 = Open cable condition
11 = Match cable condition
R/W
NASR
00b
8
TDR Channel Status
When high, this bit indicates that the TDR operation has completed. This bit
will stay high until reset or the TDR operation is restarted (TDR Enable = 1)
R/W
NASR
0b
7:0
TDR Channel Length
This eight bit value indicates the TDR channel length during a short or open
cable condition. Refer to Section 3.8.11.1, "Time Domain Reflectometry
(TDR) Cable Diagnostics," on page 56 for additional information on the
usage of this field.
R/W
NASR
00h
Note:
This field is not valid during a match cable condition. The Cable
Length Register must be used to determine cable length during a
non-open/short (match) condition. Refer to Section 3.8.11, "Cable
Diagnostics," on page 56 for additional information.
Revision 1.1 (05-10-13)
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.2.17
Symbol Error Counter Register
Index (In Decimal):
26
Size:
16 bits
BITS
DESCRIPTION
TYPE
DEFAULT
15:0
Symbol Error Counter (SYM_ERR_CNT)
This 100BASE-TX receiver-based error counter increments when an invalid
code symbol is received, including IDLE symbols. The counter is
incremented only once per packet, even when the received packet contains
more than one symbol error. This field counts up to 65,536 and rolls over to
0 if incremented beyond it’s maximum value.
RO
0000h
Note:
This register is cleared on reset, but is not cleared by reading the
register. It does not increment in 10BASE-T mode.
SMSC LAN8740A/LAN8740Ai
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DATASHEET
Revision 1.1 (05-10-13)
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.2.18
Special Control/Status Indications Register
Index (In Decimal):
BITS
27
Size:
DESCRIPTION
TYPE
DEFAULT
R/W
NASR
0b
RO
-
R/W
NASR
0b
RO
-
R/W
NASR
0b
RESERVED
RO
-
XPOL
Polarity state of the 10BASE-T:
0 = Normal polarity
1 = Reversed polarity
RO
0b
RESERVED
RO
-
15
AMDIXCTRL
HP Auto-MDIX control:
0 = Enable Auto-MDIX
1 = Disable Auto-MDIX (use 27.13 to control channel)
14
RESERVED
13
CH_SELECT
Manual channel select:
0 = MDI (TX transmits, RX receives)
1 = MDIX (TX receives, RX transmits)
12
RESERVED
11
SQEOFF
Disable the SQE test (Heartbeat):
0 = SQE test is enabled
1 = SQE test is disabled
10:5
4
3:0
16 bits
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SMSC LAN8740A/LAN8740Ai
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.2.19
Cable Length Register
Index (In Decimal):
BITS
15:12
Size:
16 bits
DESCRIPTION
Cable Length (CBLN)
This four bit value indicates the cable length. Refer to Section 3.8.11.2,
"Matched Cable Diagnostics," on page 60 for additional information on the
usage of this field.
Note:
11:0
28
TYPE
DEFAULT
RO
0000b
RO
-
This field indicates cable length for 100BASE-TX linked devices
that do not have an open/short on the cable. To determine the
open/short status of the cable, the TDR Patterns/Delay Control
Register and TDR Control/Status Register must be used. Cable
length is not supported for 10BASE-T links. Refer to Section 3.8.11,
"Cable Diagnostics," on page 56 for additional information.
RESERVED
SMSC LAN8740A/LAN8740Ai
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Revision 1.1 (05-10-13)
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.2.20
Interrupt Source Flag Register
Index (In Decimal):
BITS
15:9
29
Size:
DESCRIPTION
RESERVED
16 bits
TYPE
DEFAULT
RO
-
8
INT8
0 = Not source of interrupt
1 = Wake on LAN (WoL) event detected
RO/LH
0b
7
INT7
0 = Not source of interrupt
1 = ENERGYON generated
RO/LH
0b
6
INT6
0 = Not source of interrupt
1 = Auto-Negotiation complete
RO/LH
0b
5
INT5
0 = Not source of interrupt
1 = Remote Fault Detected
RO/LH
0b
4
INT4
0 = Not source of interrupt
1 = Link Down (link status negated)
RO/LH
0b
3
INT3
0 = Not source of interrupt
1 = Auto-Negotiation LP Acknowledge
RO/LH
0b
2
INT2
0 = Not source of interrupt
1 = Parallel Detection Fault
RO/LH
0b
1
INT1
0 = Not source of interrupt
1 = Auto-Negotiation Page Received
RO/LH
0b
0
RESERVED
RO
0b
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.2.21
Interrupt Mask Register
Index (In Decimal):
BITS
30
Size:
16 bits
DESCRIPTION
TYPE
DEFAULT
15:9
RESERVED
RO
-
8:1
Mask Bits
These bits mask the corresponding interrupts in the Interrupt Source Flag
Register.
0 = Interrupt source is masked.
1 = Interrupt source is enabled.
R/W
00000000b
RESERVED
RO
-
0
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.2.22
PHY Special Control/Status Register
Index (In Decimal):
BITS
31
Size:
16 bits
TYPE
DEFAULT
RESERVED
RO
-
Autodone
Auto-negotiation done indication:
0 = Auto-negotiation is not done or disabled (or not active).
1 = Auto-negotiation is done.
RO
0b
RESERVED
RO
-
6
Enable 4B5B
0 = Bypass encoder/decoder
1 = Enable 4B5B encoding/decoding. MAC interface must be configured in
MII mode.
R/W
1b
5
RESERVED
RO
-
4:2
Speed Indication
HCDSPEED value:
001 = 10BASE-T half-duplex
101 = 10BASE-T full-duplex
010 = 100BASE-TX half-duplex
110 = 100BASE-TX full-duplex
RO
XXXb
1:0
RESERVED
RO
-
15:13
12
11:7
DESCRIPTION
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.3
MDIO Manageable Device (MMD) Registers
The device MMD registers adhere to the IEEE 802.3-2008 45.2 MDIO Interface Registers specification.
The MMD registers are not memory mapped. These registers are accessed indirectly via the MMD
Access Control Register and MMD Access Address/Data Register. The supported MMD device
addresses are 3 (PCS), 7 (Auto-Negotiation), and 30 (Vendor Specific). Table 4.3, "MMD Registers"
details the supported registers within each MMD device.
Table 4.3 MMD Registers
MMD DEVICE
ADDRESS
(IN DECIMAL)
INDEX
(IN DECIMAL)
REGISTER NAME
0
PCS Control 1 Register
1
PCS Status 1 Register
5
PCS MMD Devices Present 1 Register
6
PCS MMD Devices Present 2 Register
20
EEE Capability Register
22
EEE Wake Error Register
32784
Wakeup Control and Status Register (WUCSR)
32785
Wakeup Filter Configuration Register A (WUF_CFGA)
32786
Wakeup Filter Configuration Register B (WUF_CFGB)
32801
3
(PCS)
32802
32803
32804
32805
Wakeup Filter Byte Mask Registers (WUF_MASK)
32806
32807
32808
SMSC LAN8740A/LAN8740Ai
32865
MAC Receive Address A Register (RX_ADDRA)
32866
MAC Receive Address B Register (RX_ADDRB)
32867
MAC Receive Address C Register (RX_ADDRC)
32868
Miscellaneous Configuration Register (MCFGR)
93
DATASHEET
Revision 1.1 (05-10-13)
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
Table 4.3 MMD Registers (continued)
MMD DEVICE
ADDRESS
(IN DECIMAL)
7
(Auto-Negotiation)
30
(Vendor Specific)
INDEX
(IN DECIMAL)
REGISTER NAME
5
Auto-Negotiation MMD Devices Present 1 Register
6
Auto-Negotiation MMD Devices Present 2 Register
60
EEE Advertisement Register
61
EEE Link Partner Advertisement Register
2
Vendor Specific MMD 1 Device ID 1 Register
3
Vendor Specific MMD 1 Device ID 2 Register
5
Vendor Specific 1 MMD Devices Present 1 Register
6
Vendor Specific 1 MMD Devices Present 2 Register
8
Vendor Specific MMD 1 Status Register
11
TDR Match Threshold Register
12
TDR Short/Open Threshold Register
14
Vendor Specific MMD 1 package ID 1 Register
15
Vendor Specific MMD 1 package ID 2 Register
To read or write an MMD register, the following procedure must be observed:
1. Write the MMD Access Control Register with 00b (address) for the MMD Function field and the
desired MMD device (3 for PCS, 7 for Auto-Negotiation) for the MMD Device Address (DEVAD)
field.
2. Write the MMD Access Address/Data Register with the 16-bit address of the desired MMD register
to read/write within the previously selected MMD device (PCS or Auto-Negotiation).
3. Write the MMD Access Control Register with 01b (data) for the MMD Function field and choose
the previously selected MMD device (3 for PCS, 7 for Auto-Negotiation) for the MMD Device
Address (DEVAD) field.
4. If reading, read the MMD Access Address/Data Register, which contains the selected MMD register
contents. If writing, write the MMD Access Address/Data Register with the register contents
intended for the previously selected MMD register.
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.3.1
PCS Control 1 Register
Index (In Decimal):
BITS
15:11
10
Size:
DESCRIPTION
16 bits
TYPE
DEFAULT
RESERVED
RO
-
Clock Stop Enable
0 = The PHY cannot stop the clock during Low Power Idle (LPI).
1 = The PHY may stop the clock during LPI.
R/W
0b
RO
-
Note:
9:0
3.0
The device does not support this mode.
RESERVED
SMSC LAN8740A/LAN8740Ai
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Datasheet
4.3.2
PCS Status 1 Register
Index (In Decimal):
BITS
15:12
3.1
Size:
DESCRIPTION
RESERVED
16 bits
TYPE
DEFAULT
RO
-
11
TX LPI Received
0 = TX PCS has not received LPI.
1 = TX PCS has received LPI.
RO/LH
0b
10
RX LPI Received
0 = RX PCS has not received LPI.
1 = RX PCS has received LPI.
RO/LH
0b
9
TX LPI Indication
0 = TX PCS is not currently receiving LPI.
1 = TX PCS is currently receiving LPI.
RO
0b
8
RX LPI Indication
0 = RX PCS is not currently receiving LPI.
1 = RX PCS is currently receiving LPI.
RO
0b
7
RESERVED
RO
-
6
Clock Stop Capable
0 = The MAC cannot stop the clock during Low Power Idle (LPI).
1 = The MAC may stop the clock during LPI.
RO
0b
RO
-
Note:
5:0
The device does not support this mode.
RESERVED
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.3.3
PCS MMD Devices Present 1 Register
Index (In Decimal):
BITS
3.5
Size:
TYPE
DEFAULT
RESERVED
RO
-
7
Auto-Negotiation Present
0 = Auto-negotiation not present in package
1 = Auto-negotiation present in package
RO
1b
6
TC Present
0 = TC not present in package
1 = TC present in package
RO
0b
5
DTE XS Present
0 = DTE XS not present in package
1 = DTE XS present in package
RO
0b
4
PHY XS Present
0 = PHY XS not present in package
1 = PHY XS present in package
RO
0b
3
PCS Present
0 = PCS not present in package
1 = PCS present in package
RO
1b
2
WIS Present
0 = WIS not present in package
1 = WIS present in package
RO
0b
1
PMD/PMA Present
0 = PMD/PMA not present in package
1 = PMD/PMA present in package
RO
0b
0
Clause 22 Registers Present
0 = Clause 22 registers not present in package
1 = Clause 22 registers present in package
RO
0b
15:8
DESCRIPTION
16 bits
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Datasheet
4.3.4
PCS MMD Devices Present 2 Register
Index (In Decimal):
BITS
3.6
Size:
DESCRIPTION
16 bits
TYPE
DEFAULT
15
Vendor Specific Device 2 Present
0 = Vendor specific device 2 not present in package
1 = Vendor specific device 2 present in package
RO
0b
14
Vendor Specific Device 1 Present
0 = Vendor specific device 1 not present in package
1 = Vendor specific device 1 present in package
RO
1b
13
Clause 22 Extension Present
0 = Clause 22 extension not present in package
1 = Clause 22 extension present in package
RO
0b
RESERVED
RO
-
12:0
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.3.5
EEE Capability Register
Index (In Decimal):
BITS
15:7
6
DEFAULT
RESERVED
RO
-
10GBASE-KR EEE
0 = EEE is not supported for 10GBASE-KR.
1 = EEE is supported for 10GBASE-KR.
RO
0b
RO
0b
RO
0b
RO
0b
RO
0b
The device does not support this mode.
10GBASE-KX EEE
0 = EEE is not supported for 10GBASE-KX.
1 = EEE is supported for 10GBASE-KX.
The device does not support this mode.
10GBASE-T EEE
0 = EEE is not supported for 10GBASE-T.
1 = EEE is supported for 10GBASE-T.
Note:
2
The device does not support this mode.
10GBASE-KX4 EEE
0 = EEE is not supported for 10GBASE-KX4.
1 = EEE is supported for 10GBASE-KX4.
Note:
3
16 bits
TYPE
Note:
4
Size:
DESCRIPTION
Note:
5
3.20
The device does not support this mode.
1000BASE-T EEE
0 = EEE is not supported for 1000BASE-T.
1 = EEE is supported for 1000BASE-T.
Note:
The device does not support this mode.
1
100BASE-TX EEE
0 = EEE is not supported for 100BASE-TX.
1 = EEE is supported for 100BASE-TX.
RO
Note 4.6
0
RESERVED
RO
-
Note 4.6
The default value of this field is determined by the value of the PHY Energy Efficient
Ethernet Enable (PHYEEEEN) of the EDPD NLP / Crossover Time / EEE Configuration
Register on page 82. If PHY Energy Efficient Ethernet Enable (PHYEEEEN) is 0b, this field
is 0b and 100BASE-TX EEE capability is not supported. If PHY Energy Efficient Ethernet
Enable (PHYEEEEN) is 1b, then this field is 1b and 100BASE-TX EEE capability is
supported.
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.3.6
EEE Wake Error Register
Index (In Decimal):
3.22
Size:
16 bits
BITS
DESCRIPTION
TYPE
DEFAULT
15:0
EEE Wake Error Counter
This counter is cleared to zeros on read and is held to all ones on overflow.
RO/RC
0000h
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.3.7
Wakeup Control and Status Register (WUCSR)
Index (In Decimal):
BITS
15
14:13
DEFAULT
Interface Disable
0 = MII/RMII interface enabled
1 = MII/RMII interface disabled. Outputs driven to a low level and inputs
ignored.
R/W
NASR
0b
LED1 Function Select
00 = LED1 functions as Link/Activity.
01 = LED1 functions as nINT.
10 = LED1 functions as nPME.
11 = LED1 functions as Link Speed.
R/W
NASR
0b
R/W
NASR
0b
R/W
NASR
0b
R/W
NASR
0b
R/W/
NASR
0b
Refer to Section 3.8.1, "LEDs," on page 43 for additional
information.
RXD2/RMIISEL Function Select
0 = RXD2/RMIISEL pin functions normally as RXD2/RMIISEL.
1 = RXD2/RMIISEL pin functions as nPME.
Refer to Section 3.8.4, "Wake on LAN (WoL)," on page 48 for
additional information.
nPME Self Clear
0 = nPME pin is not self clearing.
1 = nPME pin is self clearing.
Note:
8
Refer to Section 3.8.1, "LEDs," on page 43 for additional
information.
LED2 Function Select
00 = LED2 functions as Link Speed.
01 = LED2 functions as nINT.
10 = LED2 functions as nPME.
11 = LED2 functions as Link/Activity.
Note:
9
16 bits
TYPE
Note:
10
Size:
DESCRIPTION
Note:
12:11
3.32784
When set, the de-assertion delay of the nPME signal is controlled
by the nPME Assert Delay bit of the Miscellaneous Configuration
Register (MCFGR). Refer to Section 3.8.4, "Wake on LAN (WoL),"
on page 48 for additional information.
WoL Configured
This bit may be set by software after the WoL registers are configured. This
sticky bit (and all other WoL related register bits) is reset only via a power
cycle or a pin reset, allowing software to skip programming of the WoL
registers in response to a WoL event.
Note:
Refer to Section 3.8.4, "Wake on LAN (WoL)," on page 48 for
additional information.
7
Perfect DA Frame Received (PFDA_FR)
The MAC sets this bit upon receiving a valid frame with a destination
address that matches the physical address.
R/WC/
NASR
0b
6
Remote Wakeup Frame Received (WUFR)
The MAC sets this bit upon receiving a valid remote Wakeup Frame.
R/WC/
NASR
0b
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Datasheet
BITS
DESCRIPTION
TYPE
DEFAULT
5
Magic Packet Received (MPR)
The MAC sets this bit upon receiving a valid Magic Packet.
R/WC/
NASR
0b
4
Broadcast Frame Received (BCAST_FR)
The MAC Sets this bit upon receiving a valid broadcast frame.
R/WC/
NASR
0b
3
Perfect DA Wakeup Enable (PFDA_EN)
When set, remote wakeup mode is enabled and the MAC is capable of
waking up on receipt of a frame with a destination address that matches the
physical address of the device. The physical address is stored in the MAC
Receive Address A Register (RX_ADDRA), MAC Receive Address B
Register (RX_ADDRB) and MAC Receive Address C Register
(RX_ADDRC).
R/W/
NASR
0b
2
Wakeup Frame Enable (WUEN)
When set, remote wakeup mode is enabled and the MAC is capable of
detecting Wakeup Frames as programmed in the Wakeup Filter.
R/W/
NASR
0b
1
Magic Packet Enable (MPEN)
When set, Magic Packet wakeup mode is enabled.
R/W/
NASR
0b
0
Broadcast Wakeup Enable (BCST_EN)
When set, remote wakeup mode is enabled and the MAC is capable of
waking up from a broadcast frame.
R/W/
NASR
0b
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.3.8
Wakeup Filter Configuration Register A (WUF_CFGA)
Index (In Decimal):
BITS
3.32785
Size:
16 bits
DESCRIPTION
TYPE
DEFAULT
15
Filter Enable
0 = Filter disabled
1 = Filter enabled
R/W/
NASR
0b
14
Filter Triggered
0 = Filter not triggered
1 = Filter triggered
R/WC/
NASR
0b
RO
-
13:11
RESERVED
10
Address Match Enable
When set, the destination address must match the programmed address.
When cleared, any unicast packet is accepted. Refer to Section 3.8.4.4,
"Wakeup Frame Detection," on page 51 for additional information.
R/W/
NASR
0b
9
Filter Any Multicast Enable
When set, any multicast packet other than a broadcast will cause an address
match. Refer to Section 3.8.4.4, "Wakeup Frame Detection," on page 51 for
additional information.
R/W/
NASR
0b
R/W/
NASR
0b
R/W/
NASR
00h
Note:
8
Filter Broadcast Enable
When set, any broadcast frame will cause an address match. Refer to
Section 3.8.4.4, "Wakeup Frame Detection," on page 51 for additional
information.
Note:
7:0
This bit has priority over bit 10 of this register.
This bit has priority over bit 10 of this register.
Filter Pattern Offset
Specifies the offset of the first byte in the frame on which CRC checking
begins for Wakeup Frame recognition. Offset 0 is the first byte of the
incoming frame’s destination address.
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.3.9
Wakeup Filter Configuration Register B (WUF_CFGB)
Index (In Decimal):
3.32786
Size:
16 bits
BITS
DESCRIPTION
TYPE
DEFAULT
15:0
Filter CRC-16
This field specifies the expected 16-bit CRC value for the filter that should
be obtained by using the pattern offset and the byte mask programmed for
the filter. This value is compared against the CRC calculated on the incoming
frame, and a match indicates the reception of a Wakeup Frame.
R/W/
NASR
0000h
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.3.10
Wakeup Filter Byte Mask Registers (WUF_MASK)
Index (In Decimal):
BITS
15:0
3.32802
Size:
Wakeup Filter Byte Mask [111:96]
BITS
3.32803
Size:
Wakeup Filter Byte Mask [95:80]
BITS
3.32804
Size:
DESCRIPTION
Wakeup Filter Byte Mask [79:64]
SMSC LAN8740A/LAN8740Ai
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DATASHEET
DEFAULT
R/W/
NASR
0000h
TYPE
DEFAULT
R/W/
NASR
0000h
TYPE
DEFAULT
R/W/
NASR
0000h
TYPE
DEFAULT
R/W/
NASR
0000h
16 bits
DESCRIPTION
Index (In Decimal):
TYPE
16 bits
DESCRIPTION
Index (In Decimal):
15:0
16 bits
Wakeup Filter Byte Mask [127:112]
BITS
15:0
Size:
DESCRIPTION
Index (In Decimal):
15:0
3.32801
16 bits
Revision 1.1 (05-10-13)
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
Index (In Decimal):
BITS
15:0
3.32806
Size:
Wakeup Filter Byte Mask [47:32]
BITS
3.32807
Size:
Wakeup Filter Byte Mask [31:16]
BITS
3.32808
Size:
DESCRIPTION
Wakeup Filter Byte Mask [15:0]
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DATASHEET
DEFAULT
R/W/
NASR
0000h
TYPE
DEFAULT
R/W/
NASR
0000h
TYPE
DEFAULT
R/W/
NASR
0000h
TYPE
DEFAULT
R/W/
NASR
0000h
16 bits
DESCRIPTION
Index (In Decimal):
TYPE
16 bits
DESCRIPTION
Index (In Decimal):
15:0
16 bits
Wakeup Filter Byte Mask [63:48]
BITS
15:0
Size:
DESCRIPTION
Index (In Decimal):
15:0
3.32805
16 bits
SMSC LAN8740A/LAN8740Ai
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.3.11
MAC Receive Address A Register (RX_ADDRA)
Index (In Decimal):
BITS
15:0
3.32865
Size:
DESCRIPTION
Physical Address [47:32]
16 bits
TYPE
DEFAULT
R/W/
NASR
FFFFh
Note: The MAC address must be loaded into the RX_ADDRA, RX_ADDRB, and RX_ADDRC
registers in the proper byte order. For example, a MAC address of 12:34:56:78:9A:BC should
be loaded into these registers as follows:
RX_ADDRA = BC9Ah
RX_ADDRB = 7856h
RX_ADDRC = 3412h
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.3.12
MAC Receive Address B Register (RX_ADDRB)
Index (In Decimal):
BITS
15:0
3.32866
Size:
DESCRIPTION
Physical Address [31:16]
16 bits
TYPE
DEFAULT
R/W/
NASR
FFFFh
Note: The MAC address must be loaded into the RX_ADDRA, RX_ADDRB, and RX_ADDRC
registers in the proper byte order. For example, a MAC address of 12:34:56:78:9A:BC should
be loaded into these registers as follows:
RX_ADDRA = BC9Ah
RX_ADDRB = 7856h
RX_ADDRC = 3412h
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.3.13
MAC Receive Address C Register (RX_ADDRC)
Index (In Decimal):
BITS
15:0
3.32867
Size:
DESCRIPTION
Physical Address [15:0]
16 bits
TYPE
DEFAULT
R/W/
NASR
FFFFh
Note: The MAC address must be loaded into the RX_ADDRA, RX_ADDRB, and RX_ADDRC
registers in the proper byte order. For example, a MAC address of 12:34:56:78:9A:BC should
be loaded into these registers as follows:
RX_ADDRA = BC9Ah
RX_ADDRB = 7856h
RX_ADDRC = 3412h
SMSC LAN8740A/LAN8740Ai
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.3.14
Miscellaneous Configuration Register (MCFGR)
Index (In Decimal):
3.32868
Size:
16 bits
BITS
DESCRIPTION
TYPE
DEFAULT
15:0
nPME Assert Delay
This register controls the delay of nPME de-assertion time when the nPME
Self Clear bit of the Wakeup Control and Status Register (WUCSR) is set.
Each count is equivalent to a 20 µs delay. The delay max is 1.31 seconds.
Time = (register value + 1) x 20 µs.
R/W/
NASR
1000h
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.3.15
Auto-Negotiation MMD Devices Present 1 Register
Index (In Decimal):
BITS
7.5
Size:
TYPE
DEFAULT
RESERVED
RO
-
7
Auto-Negotiation Present
0 = Auto-negotiation not present in package
1 = Auto-negotiation present in package
RO
1b
6
TC Present
0 = TC not present in package
1 = TC present in package
RO
0b
5
DTE XS Present
0 = DTE XS not present in package
1 = DTE XS present in package
RO
0b
4
PHY XS Present
0 = PHY XS not present in package
1 = PHY XS present in package
RO
0b
3
PCS Present
0 = PCS not present in package
1 = PCS present in package
RO
1b
2
WIS Present
0 = WIS not present in package
1 = WIS present in package
RO
0b
1
PMD/PMA Present
0 = PMD/PMA not present in package
1 = PMD/PMA present in package
RO
0b
0
Clause 22 Registers Present
0 = Clause 22 registers not present in package
1 = Clause 22 registers present in package
RO
0b
15:8
DESCRIPTION
16 bits
SMSC LAN8740A/LAN8740Ai
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.3.16
Auto-Negotiation MMD Devices Present 2 Register
Index (In Decimal):
BITS
7.6
Size:
DESCRIPTION
16 bits
TYPE
DEFAULT
15
Vendor Specific Device 2 Present
0 = Vendor specific device 2 not present in package
1 = Vendor specific device 2 present in package
RO
0b
14
Vendor Specific Device 1 Present
0 = Vendor specific device 1 not present in package
1 = Vendor specific device 1 present in package
RO
1b
13
Clause 22 Extension Present
0 = Clause 22 extension not present in package
1 = Clause 22 extension present in package
RO
0b
RESERVED
RO
-
12:0
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.3.17
EEE Advertisement Register
Index (In Decimal):
BITS
15:2
7.60
Size:
DESCRIPTION
RESERVED
1
100BASE-TX EEE
0 = Do not advertise EEE capability for 100BASE-TX.
1 = Advertise EEE capability for 100BASE-TX.
0
RESERVED
16 bits
TYPE
DEFAULT
RO
-
Note 4.7
Note 4.8
RO
-
Note 4.7
This bit is read/write (R/W). However, the user must not set this bit if EEE is disabled.
Note 4.8
The default value of this field is determined by the value of the PHY Energy Efficient
Ethernet Enable (PHYEEEEN) of the EDPD NLP / Crossover Time / EEE Configuration
Register on page 82. If PHY Energy Efficient Ethernet Enable (PHYEEEEN) is 0b, this field
is 0b and 100BASE-TX EEE capability is not advertised. If PHY Energy Efficient Ethernet
Enable (PHYEEEEN) is 1b, then this field is 1b and 100BASE-TX EEE capability is
advertised.
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Datasheet
4.3.18
EEE Link Partner Advertisement Register
Index (In Decimal):
BITS
15:7
6
DEFAULT
RESERVED
RO
-
10GBASE-KR EEE
0 = Link partner does not advertise EEE capability for 10GBASE-KR.
1 = Link partner advertises EEE capability for 10GBASE-KR.
RO
0b
RO
0b
RO
0b
RO
0b
RO
0b
This device does not support this mode.
10GBASE-KX EEE
0 = Link partner does not advertise EEE capability for 10GBASE-KX.
1 = Link partner advertises EEE capability for 10GBASE-KX.
This device does not support this mode.
10GBASE-T EEE
0 = Link partner does not advertise EEE capability for 10GBASE-T.
1 = Link partner advertises EEE capability for 10GBASE-T.
Note:
2
This device does not support this mode.
10GBASE-KX4 EEE
0 = Link partner does not advertise EEE capability for 10GBASE-KX4.
1 = Link partner advertises EEE capability for 10GBASE-KX4.
Note:
3
16 bits
TYPE
Note:
4
Size:
DESCRIPTION
Note:
5
7.61
This device does not support this mode.
1000BASE-T EEE
0 = Link partner does not advertise EEE capability for 1000BASE-T.
1 = Link partner advertises EEE capability for 1000BASE-T.
Note:
This device does not support this mode.
1
100BASE-TX EEE
0 = Link partner does not advertise EEE capability for 100BASE-TX.
1 = Link partner advertises EEE capability for 100BASE-TX.
RO
0b
0
RESERVED
RO
-
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.3.19
Vendor Specific MMD 1 Device ID 1 Register
Index (In Decimal):
BITS
15:0
30.2
Size:
DESCRIPTION
RESERVED
SMSC LAN8740A/LAN8740Ai
115
DATASHEET
16 bits
TYPE
DEFAULT
RO
0000h
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.3.20
Vendor Specific MMD 1 Device ID 2 Register
Index (In Decimal):
BITS
15:0
30.3
Size:
DESCRIPTION
RESERVED
Revision 1.1 (05-10-13)
116
DATASHEET
16 bits
TYPE
DEFAULT
RO
0000h
SMSC LAN8740A/LAN8740Ai
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.3.21
Vendor Specific 1 MMD Devices Present 1 Register
Index (In Decimal):
BITS
30.5
Size:
TYPE
DEFAULT
RESERVED
RO
-
7
Auto-Negotiation Present
0 = Auto-negotiation not present in package
1 = Auto-negotiation present in package
RO
1b
6
TC Present
0 = TC not present in package
1 = TC present in package
RO
0b
5
DTE XS Present
0 = DTE XS not present in package
1 = DTE XS present in package
RO
0b
4
PHY XS Present
0 = PHY XS not present in package
1 = PHY XS present in package
RO
0b
3
PCS Present
0 = PCS not present in package
1 = PCS present in package
RO
1b
2
WIS Present
0 = WIS not present in package
1 = WIS present in package
RO
0b
1
PMD/PMA Present
0 = PMD/PMA not present in package
1 = PMD/PMA present in package
RO
0b
0
Clause 22 Registers Present
0 = Clause 22 registers not present in package
1 = Clause 22 registers present in package
RO
0b
15:8
DESCRIPTION
16 bits
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4.3.22
Vendor Specific 1 MMD Devices Present 2 Register
Index (In Decimal):
BITS
30.6
Size:
DESCRIPTION
16 bits
TYPE
DEFAULT
15
Vendor Specific Device 2 Present
0 = Vendor specific device 2 not present in package
1 = Vendor specific device 2 present in package
RO
0b
14
Vendor Specific Device 1 Present
0 = Vendor specific device 1 not present in package
1 = Vendor specific device 1 present in package
RO
1b
13
Clause 22 Extension Present
0 = Clause 22 extension not present in package
1 = Clause 22 extension present in package
RO
0b
RESERVED
RO
-
12:0
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Datasheet
4.3.23
Vendor Specific MMD 1 Status Register
Index (In Decimal):
BITS
30.8
Size:
DESCRIPTION
15:14
Device Present
00 = No device responding at this address
01 = No device responding at this address
10 = Device responding at this address
11 = No device responding at this address
13:0
RESERVED
SMSC LAN8740A/LAN8740Ai
16 bits
TYPE
DEFAULT
10b
RO
119
DATASHEET
-
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Datasheet
4.3.24
TDR Match Threshold Register
Index (In Decimal):
BITS
30.11
Size:
TYPE
DEFAULT
RESERVED
RO
-
9:5
TDR Match High Threshold
Sets the upper threshold to detect match cable.
R/W
5’h12
Note 4.9
4:0
TDR Match Low Threshold
Sets the lower threshold to detect match cable.
R/W
5’h09
Note 4.9
15:10
DESCRIPTION
16 bits
Note 4.9
Revision 1.1 (05-10-13)
Software reset places the default values of this register into an indeterminate state. For
proper operation of the TDR, the TDR Match High Threshold and TDR Match Low
Threshold must be set to 5’h12 and 5’h09, respectively.
120
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4.3.25
TDR Short/Open Threshold Register
Index (In Decimal):
BITS
30.12
Size:
TYPE
DEFAULT
RESERVED
RO
-
9:5
TDR Short Low Threshold
Sets the lower threshold to detect short cable.
R/W
5’h09
Note 4.10
4:0
TDR Open High Threshold
Sets the upper threshold to detect open cable.
R/W
5’h12
Note 4.10
15:10
DESCRIPTION
16 bits
Note 4.10 Software reset places the default values of this register into an indeterminate state. For
proper operation of the TDR, the TDR Short Low Threshold and TDR Open High Threshold
must be set to 5’h09 and 5’h12, respectively.
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4.3.26
Vendor Specific MMD 1 package ID 1 Register
Index (In Decimal):
BITS
15:0
30.14
Size:
DESCRIPTION
RESERVED
Revision 1.1 (05-10-13)
122
DATASHEET
16 bits
TYPE
DEFAULT
RO
0000h
SMSC LAN8740A/LAN8740Ai
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
4.3.27
Vendor Specific MMD 1 package ID 2 Register
Index (In Decimal):
BITS
15:0
30.15
Size:
DESCRIPTION
RESERVED
SMSC LAN8740A/LAN8740Ai
123
DATASHEET
16 bits
TYPE
DEFAULT
RO
0000h
Revision 1.1 (05-10-13)
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
Chapter 5 Operational Characteristics
5.1
Absolute Maximum Ratings*
Supply Voltage (VDDIO, VDD1A, VDD2A) (Note 5.1) . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5 V to +3.6 V
Digital Core Supply Voltage (VDDCR) (Note 5.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5 V to +1.5 V
Ethernet Magnetics Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5 V to +3.6 V
Positive voltage on input signal pins, with respect to ground (Note 5.2) . . . . . . . . . . . .VDDIO + 2.0 V
Negative voltage on input signal pins, with respect to ground (Note 5.3). . . . . . . . . . . . . . . . . . . -0.5 V
Positive voltage on XTAL1/CLKIN, with respect to ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6 V
Storage Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-55oC to +150oC
Lead Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Refer to JEDEC Spec. J-STD-020
HBM ESD Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .JEDEC Class 3A
Note 5.1
When powering this device from laboratory or system power supplies, it is important that
the absolute maximum ratings not be exceeded or device failure can result. Some power
supplies exhibit voltage spikes on their outputs when AC power is switched on or off. In
addition, voltage transients on the AC power line may appear on the DC output. If this
possibility exists, it is suggested that a clamp circuit be used.
Note 5.2
This rating does not apply to the following pins: XTAL1/CLKIN, XTAL2, RBIAS.
Note 5.3
This rating does not apply to the following pins: RBIAS.
*Stresses exceeding those listed in this section could cause permanent damage to the device. This is
a stress rating only. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability. Functional operation of the device at any condition exceeding those indicated in
Section 5.2, "Operating Conditions**" or any other applicable section of this specification is not implied.
Note, device signals are NOT 5.0 V tolerant unless specified otherwise.
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Datasheet
5.2
Operating Conditions**
Supply Voltage (VDDIO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +1.62 V to +3.6 V
Analog Port Supply Voltage (VDD1A, VDD2A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +3.0 V to +3.6 V
Digital Core Supply Voltage (VDDCR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +1.14 V to +1.26 V
Ethernet Magnetics Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +2.25 V to +3.6 V
Ambient Operating Temperature in Still Air (TA). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Note 5.4
Note 5.4
0°C to +70°C for commercial version, -40°C to +85°C for industrial version.
**Proper operation of the device is guaranteed only within the ranges specified in this section. After
the device has completed power-up, VDDIO and the magnetics power supply must maintain their
voltage level with ±10%. Varying the voltage greater than ±10% after the device has completed powerup can cause errors in device operation.
Note: Do not drive input signals without power supplied to the device.
5.3
Package Thermal Specifications
Table 5.1 Package Thermal Parameters
PARAMETER
SYMBOL
VALUE
UNITS
COMMENTS
Thermal Resistance
ΘJA
47.8
oC/W
Measured in still air from the die to ambient air
Junction-to-Top-of-Package
ΨJT
0.7
oC/W
Measured in still air
Note: Thermal parameters are measured or estimated for devices in a multi-layer 2S2P PCB per
JESD51.
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5.4
Power Consumption
This section details the device power measurements taken over various operating conditions. Unless
otherwise noted, all measurements were taken with power supplies at nominal values (VDDIO, VDD1A,
VDD2A = 3.3 V, VDDCR = 1.2 V). See Section 3.8.3, "Power-Down Modes," on page 47 for a
description of the power down modes.
5.4.1
Regulator Disabled
Table 5.2 Current Consumption and Power Dissipation (Reg. Disabled)
POWER PIN GROUP
3.3 V DEVICE
CURRENT
(mA)
1.2 V DEVICE
CURRENT
(mA)
3.3 V DEVICE
CURRENT W/
MAGNETICS
(mA)
TOTAL
DEVICE
POWER
(mW)
nRESET
Typical
9.7
11
9.7
45
100BASE-TX /W TRAFFIC
(NO EEE)
Typical
32
21
74
130
10BASE-T /W TRAFFIC
Typical
11
13
114
51
100BASE-TX IDLE /W EEE
Typical
32
15
32
122
ENERGY DETECT
POWER DOWN
Typical
4.0
1.7
4.0
15
GENERAL POWER DOWN
Typical
0.3
1.4
0.4
2.8
5.4.2
Regulator Enabled
Table 5.3 Current Consumption and Power Dissipation (Reg. Enabled)
POWER PIN GROUP
DEVICE
CURRENT
(mA)
DEVICE
CURRENT W/
MAGNETICS
(mA)
TOTAL
DEVICE
POWER
(mW)
nRESET
Typical
21
21
70
100BASE-TX /W TRAFFIC
(NO EEE)
Typical
55
97
180
10BASE-T /W TRAFFIC
Typical
25
129
82
100BASE-TX IDLE /W EEE
Typical
48
48
158
ENERGY DETECT
POWER DOWN
Typical
7.1
7.1
24
GENERAL POWER DOWN
Typical
4.0
4.0
13
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5.5
DC Specifications
Table 5.4 details the non-variable I/O buffer characteristics. These buffer types do not support variable
voltage operation. Table 5.5 details the variable voltage I/O buffer characteristics. Typical values are
provided for 1.8 V, 2.5 V, and 3.3 V VDDIO cases.
Table 5.4 Non-Variable I/O Buffer Characteristics
PARAMETER
SYMBOL
MIN
Low Input Level
VILI
-0.3
High Input Level
VIHI
Negative-Going Threshold
VILT
1.01
Positive-Going Threshold
VIHT
Schmitt Trigger Hysteresis
(VIHT - VILT)
TYP
MAX
UNITS
NOTES
IS Type Input Buffer
V
3.6
V
1.19
1.39
V
Schmitt trigger
1.39
1.59
1.79
V
Schmitt trigger
VHYS
336
399
459
mV
Input Leakage
(VIN = VSS or VDDIO)
IIH
-10
10
µA
Input Capacitance
CIN
2
pF
Low Output Level
VOL
0.4
V
IOL = 12 mA
High Output Level
VOH
V
IOH = -12 mA
Note 5.5
O12 Type Buffers
VDD2A - 0.4
Note 5.6
ICLK Type Buffer
(XTAL1 Input)
Low Input Level
VILI
-0.3
0.35
V
High Input Level
VIHI
VDDCR-0.35
3.6
V
Note 5.5
This specification applies to all inputs and tri-stated bi-directional pins. Internal pull-down
and pull-up resistors add ±50 µA per-pin (typical).
Note 5.6
XTAL1/CLKIN can optionally be driven from a 25 MHz single-ended clock oscillator.
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Table 5.5 Variable I/O Buffer Characteristics
PARAMETER
1.8 V
TYP
2.5 V
TYP
SYMBOL
MIN
Low Input Level
VILI
-0.3
High Input Level
VIHI
Neg-Going Threshold
VILT
0.64
0.83
1.15
Pos-Going Threshold
VIHT
0.81
0.99
Schmitt Trigger
Hysteresis (VIHT - VILT)
VHYS
102
158
Input Leakage
(VIN = VSS or VDDIO)
IIH
-10
Input Capacitance
3.3 V
TYP
MAX
UNITS
NOTES
VIS Type Input Buffer
V
3.6
V
1.41
1.76
V
Schmitt trigger
1.29
1.65
1.90
V
Schmitt trigger
136
138
288
mV
10
µA
CIN
2
pF
Low Output Level
VOL
0.4
V
IOL = 8 mA
High Output Level
VOH
V
IOH = -8 mA
V
IOL = 8 mA
Note 5.7
VO8 Type Buffers
VDDIO - 0.4
VOD8 Type Buffer
Low Output Level
Note 5.7
0.4
VOL
This specification applies to all inputs and tri-stated bi-directional pins. Internal pull-down
and pull-up resistors add ±50 µA per-pin (typical).
Table 5.6 100BASE-TX Transceiver Characteristics
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
NOTES
Peak Differential Output Voltage High
VPPH
950
-
1050
mVpk
Note 5.8
Peak Differential Output Voltage Low
VPPL
-950
-
-1050
mVpk
Note 5.8
Signal Amplitude Symmetry
VSS
98
-
102
%
Note 5.8
Signal Rise and Fall Time
TRF
3.0
-
5.0
ns
Note 5.8
Rise and Fall Symmetry
TRFS
-
-
0.5
ns
Note 5.8
Duty Cycle Distortion
DCD
35
50
65
%
Note 5.9
Overshoot and Undershoot
VOS
-
-
5
%
1.4
ns
Jitter
Note 5.8
Measured at line side of transformer, line replaced by 100 Ω (±1%) resistor.
Note 5.9
Offset from 16 ns pulse width at 50% of pulse peak.
Note 5.10
Note 5.10 Measured differentially.
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Table 5.7 10BASE-T Transceiver Characteristics
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
NOTES
Transmitter Peak Differential Output Voltage
VOUT
2.2
2.5
2.8
V
Note 5.11
Receiver Differential Squelch Threshold
VDS
300
420
585
mV
Note 5.11 Min/max voltages guaranteed as measured with 100 Ω resistive load.
5.6
AC Specifications
This section details the various AC timing specifications of the device.
5.6.1
Equivalent Test Load
Output timing specifications assume a 25 pF equivalent test load, unless otherwise noted, as illustrated
in Figure 5.1 below.
OUTPUT
25 pF
Figure 5.1 Output Equivalent Test Load
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5.6.2
Power-On nRST & Configuration Strap Timing
This diagram illustrates the nRST reset and configuration strap timing requirements in relation to
power-on. A hardware reset (nRST assertion) is required following power-up. For proper operation,
nRST must be asserted for no less than trstia. The nRST pin can be asserted at any time, but must
not be deasserted before tpurstd after all external power supplies have reached operational levels. In
order for valid configuration strap values to be read at power-up, the tcss and tcsh timing constraints
must be followed. Refer to Section 3.8.7, "Resets," on page 54 for additional information.
All External
Power Supplies
Vopp
tpurstd
tpurstv
trstia
nRST
tcss
tcsh
Configuration Strap
Pins Input
totaa
todad
Configuration Strap
Pins Output Drive
Figure 5.2 Power-On nRST & Configuration Strap Timing
Table 5.8 Power-On nRST & Configuration Strap Timing Values
SYMBOL
DESCRIPTION
MIN
TYP
MAX
UNITS
tpurstd
External power supplies at operational level to nRST
deassertion
25
ms
tpurstv
External power supplies at operational level to nRST
valid
0
ns
trstia
nRST input assertion time
100
µs
tcss
Configuration strap pins setup to nRST deassertion
200
ns
tcsh
Configuration strap pins hold after nRST deassertion
1
ns
totaa
Output tri-state after nRST assertion
todad
Output drive after nRST deassertion
2
50
ns
800
ns
(Note 5.12)
Note: nRST deassertion must be monotonic.
Note: Device configuration straps are latched as a result of nRST assertion. Refer to Section 3.7,
"Configuration Straps," on page 39 for details. Configuration straps must only be pulled high or
low and must not be driven as inputs.
Note 5.12 20 clock cycles for 25 MHz, or 40 clock cycles for 50 MHz
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5.6.3
MII Interface Timing
This section specifies the MII interface transmit and receive timing. Please refer to Section 3.4.1, "MII,"
on page 32 for additional details.
tclkp
tclkh tclkl
RXCLK
(OUTPUT)
tval
tval
tinvld
RXD[3:0]
(OUTPUTS)
tinvld
tval
RXDV, RXER
(OUTPUTS)
Figure 5.3 MII Receive Timing
Table 5.9 MII Receive Timing Values
SYMBOL
DESCRIPTION
MIN
TYP
MAX
UNITS
NOTES
tclkp
RXCLK period
Note 5.13
tclkh
RXCLK high time
tclkp * 0.4
tclkp * 0.6
ns
tclkl
RXCLK low time
tclkp * 0.4
tclkp * 0.6
ns
tval
RXD[3:0], RXDV, RXER output
valid from rising edge of RXCLK
28.0
ns
Note 5.14
ns
Note 5.14
tinvld
RXD[3:0], RXDV, RXER output
invalid from rising edge of RXCLK
ns
10.0
Note 5.13 40 ns for 100BASE-TX operation, 400 ns for 10BASE-T operation.
Note 5.14 Timing was designed for system load between 10 pF and 25 pF.
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tclkp
tclkh
TXCLK
(OUTPUT)
tclkl
tsu thold
tsu thold
thold
TXD[3:0]
(INPUTS)
thold
tsu
TXEN, TXER
(INPUTS)
Figure 5.4 MII Transmit Timing
Table 5.10 MII Transmit Timing Values
SYMBOL
DESCRIPTION
MIN
TYP
MAX
UNITS
NOTES
tclkp
TXCLK period
Note 5.15
tclkh
TXCLK high time
tclkp * 0.4
tclkp * 0.6
ns
tclkl
TXCLK low time
tclkp * 0.4
tclkp * 0.6
ns
tsu
TXD[3:0], TXEN, TXER setup time
to rising edge of TXCLK
12.0
ns
Note 5.16
thold
TXD[3:0], TXEN, TXER hold time
after rising edge of TXCLK
0
ns
Note 5.16
ns
Note 5.16
t1
TXCLK rising edge after TXEN
assertion to RXDV assertion
(100 Mbps internal loopback
mode)
160
ns
162
Note 5.15 40 ns for 100BASE-TX operation, 400 ns for 10BASE-T operation.
Note 5.16 Timing was designed for system load between 10 pF and 25 pF.
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5.6.3.1
100 Mbps Internal Loopback MII Timing
TXCLK
(OUTPUT)
TXEN
(INPUT)
t1
RXDV
(OUTPUT)
RXD[3:0]
(OUTPUTS)
Figure 5.5 100 Mbps Internal Loopback MII Timing
Table 5.11 100 Mbps Internal Loopback MII Timing Values
SYMBOL
t1
DESCRIPTION
TXCLK rising edge after TXEN assertion to
RXDV assertion
(100 Mbps internal loopback MII mode)
MIN
TYPICAL
MAX
UNITS
160
161
162
ns
Note: The t1 measurement applies in MII mode when the Loopback bit of the Basic Control Register
is set to “1” and a link has been established in 100 Mb full-duplex mode. The t1 measurement
is taken from the first rising edge of TXCLK following assertion of TXEN to the rising edge of
RXDV.
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5.6.4
RMII Interface Timing
This section specifies the RMII interface transmit and receive timing.
Note: The CRS_DV pin performs both carrier sense and data valid functions. CRS_DV is asserted
asynchronously on detection of carrier due to the criteria relevant to the operating mode. If the
PHY has additional bits to be presented on RXD[1:0] following the initial deassertion of
CRS_DV, then the device will assert CRS_DV on cycles of REF_CLK which present the
second di-bit of each nibble and deassert CRS_DV on cycles of REF_CLK which present the
first di-bit of a nibble. For additional information, refer to the RMII specification.
tclkp
tclkh
CLKIN
(REF_CLK)
tclkl
toval
(INPUT)
toval
toinvld
RXD[1:0], RXER
(OUTPUTS)
toinvld
toval
CRS_DV
(OUTPUT)
tsu tihold
tsu tihold
tihold
TXD[1:0]
(INPUTS)
tihold
tsu
TXEN
(INPUT)
Figure 5.6 RMII Timing
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
Table 5.12 RMII Timing Values
SYMBOL
DESCRIPTION
MIN
TYP
MAX
UNITS
NOTES
tclkp
CLKIN period
tclkh
CLKIN high time
tclkp * 0.35
tclkp * 0.65
ns
tclkl
CLKIN low time
tclkp * 0.35
tclkp * 0.65
ns
toval
RXD[1:0], RXER, CRS_DV output
valid from rising edge of CLKIN
15.0
ns
Note 5.17
toinvld
RXD[1:0], RXER, CRS_DV output
invalid from rising edge of CLKIN
3.0
ns
Note 5.17
TXD[1:0], TXEN setup time to
rising edge of CLKIN
4.0
ns
Note 5.17
TXD[1:0], TXEN input hold time
after rising edge of CLKIN
1.5
ns
Note 5.17
tsu
tihold
20
ns
Note 5.17 Timing was designed for system load between 10 pF and 25 pF.
5.6.4.1
RMII CLKIN Requirements
Table 5.13 RMII CLKIN (REF_CLK) Timing Values
PARAMETER
MIN
TYP
CLKIN frequency
50
CLKIN Frequency Drift
CLKIN Duty Cycle
40
CLKIN Jitter
SMSC LAN8740A/LAN8740Ai
MAX
135
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UNITS
NOTES
MHz
±50
ppm
60
%
150
ps
p-p – not RMS
Revision 1.1 (05-10-13)
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
5.6.5
SMI Timing
This section specifies the SMI timing of the device. Please refer to Section 3.5, "Serial Management
Interface (SMI)," on page 35 for additional details.
tclkp
tclkh
MDC
(INPUT)
tval
tclkl
toinvld
toinvld
MDIO
(Data-Out)
tsu tihold
MDIO
(Data-In)
Figure 5.7 SMI Timing
Table 5.14 SMI Timing Values
SYMBOL
DESCRIPTION
tclkp
MDC period
tclkh
MIN
MAX
UNITS
400
ns
MDC high time
160 (80%)
ns
tclkl
MDC low time
160 (80%)
ns
tval
MDIO (read from PHY) output valid from rising edge of MDC
toinvld
MDIO (read from PHY) output invalid from rising edge of MDC
0
ns
MDIO (write to PHY) setup time to rising edge of MDC
10
ns
MDIO (write to PHY) input hold time after rising edge of MDC
10
ns
tsu
tihold
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300
ns
SMSC LAN8740A/LAN8740Ai
Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
5.7
Clock Circuit
The device can accept either a 25 MHz crystal or a 25 MHz single-ended clock oscillator (±50 ppm)
input. If the single-ended clock oscillator method is implemented, XTAL2 should be left unconnected
and XTAL1/CLKIN should be driven with a clock signal that adheres to the specifications outlined
throughout Chapter 5, Operational Characteristics. See Table 5.15 for the recommended crystal
specifications.
Table 5.15 Crystal Specifications
PARAMETER
SYMBOL
MIN
NOM
Crystal Cut
MAX
UNITS
NOTES
AT, typ
Crystal Oscillation Mode
Fundamental Mode
Crystal Calibration Mode
Parallel Resonant Mode
Ffund
-
25.000
-
MHz
Ftol
-
-
±50
ppm
Note 5.18
Frequency Stability Over Temp
Ftemp
-
-
±50
ppm
Note 5.18
Frequency Deviation Over Time
Fage
-
±3 to 5
-
ppm
Note 5.19
-
-
±50
ppm
Note 5.20
Frequency
Frequency Tolerance at
25oC
Total Allowable PPM Budget
Shunt Capacitance
CO
-
7 typ
-
pF
Load Capacitance
CL
-
20 typ
-
pF
Drive Level
PW
300
-
-
µW
Equivalent Series Resistance
R1
-
-
30
Ω
Operating Temperature Range
Note 5.21
-
Note 5.22
oC
XTAL1/CLKIN Pin Capacitance
-
3 typ
-
pF
Note 5.23
XTAL2 Pin Capacitance
-
3 typ
-
pF
Note 5.23
Note 5.18 The maximum allowable values for frequency tolerance and frequency stability are
application dependant. Since any particular application must meet the IEEE ±50 ppm Total
PPM Budget, the combination of these two values must be approximately ±45 ppm
(allowing for aging).
Note 5.19 Frequency Deviation Over Time is also referred to as Aging.
Note 5.20 The total deviation for the Transmitter Clock Frequency is specified by IEEE 802.3u as
±100 ppm.
Note 5.21 0°C for commercial version, -40°C for industrial version
Note 5.22 +70°C for commercial version, +85°C for industrial version
Note 5.23 This number includes the pad, the bond wire and the lead frame. PCB capacitance is not
included in this value. The XTAL1/CLKIN pin, XTAL2 pin and PCB capacitance values are
required to accurately calculate the value of the two external load capacitors. The total load
capacitance must be equivalent to what the crystal expects to see in the circuit so that the
crystal oscillator will operate at 25.000 MHz.
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
Chapter 6 Package Outline
Figure 6.1 32-SQFN Package
Table 6.1 32-SQFN Dimensions
MIN
0.80
0
4.90
3.20
0.35
0.18
0.35
A
A1
D/E
D2/E2
L
b
k
e
NOMINAL
0.90
0.02
5.00
3.30
0.40
0.25
0.45
0.50 BSC
MAX
1.00
0.05
5.10
3.40
0.45
0.30
-
REMARKS
Overall Package Height
Standoff
X/Y Body Size
X/Y Exposed Pad Size
Terminal Length
Terminal Width
Pin to Exposed Pad Clearance
Terminal Pitch
Notes:
1. All dimensions are in millimeters unless otherwise noted.
2.
3.
Dimension “b” applies to plated terminals and is measured between 0.15 and 0.30 mm from the terminal tip.
The pin 1 identifier may vary, but is always located within the zone indicated.
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
Figure 6.2 Recommended PCB Land Pattern
Figure 6.3 Taping Dimensions and Part Orientation
SMSC LAN8740A/LAN8740Ai
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
Figure 6.4 Reel Dimensions
Figure 6.5 Tape Length and Part Quantity
Note: Standard reel size is 4,000 pieces per reel.
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
Chapter 7 Revision History
Table 7.1 Customer Revision History
REVISION LEVEL
& DATE
Rev. 1.1
(05-10-13)
SECTION/FIGURE/ENTRY
CORRECTION
General
Changed part numbers from
“LAN8740/LAN8740i” to “LAN8740A/LAN8740Ai”
Updated ordering information
Updated figures
Cover
Added new bullet under Highlights section:
“Deterministic 100 Mb internal loopback latency
(MII Mode)”
Chapter 2, Pin Description and
Configuration, Table 2.1, “MII/RMII
Signals,” on page 11
Changed buffer type from “VIS (PU)” to “VIS”
Chapter 2, Pin Description and
Configuration, Table 2.3, “Serial
Management Interface (SMI) Pins,” on
page 17
Section 3.3, "HP Auto-MDIX Support,"
on page 31
Changed “100BASE-T” to “100BASE-TX”
Section 3.4.2.1, "CRS_DV - Carrier
Sense/Receive Data Valid," on
page 33
Changed “100BASE-X” to “100BASE-TX”
Section 3.5, "Serial Management
Interface (SMI)," on page 35
Removed sentence stating “Non-supported
registers (such as 7 to 15) will be read as
hexadecimal “FFFF”.
Section 3.8.11, "Cable Diagnostics,"
on page 56
Updated section with additional operation details
Section 3.8.12.1, "Near-end
Loopback," on page 61
Added cross-reference to 100 Mbps internal
loopback timing section
Chapter 4, "Register Descriptions," on
page 68
Removed
- TDR Channel Threshold Maximum Register
- TDR Wait Counter Threshold Register
- TDR TX Pattern Generator Divider Register
Section 4.2.2, "Basic Status Register,"
on page 71
Updated definitions of bits 10:8
Section 4.2.18, "Special
Control/Status Indications Register,"
on page 88
Updated bit 11 definition
Section 4.2.22, "PHY Special
Control/Status Register," on page 92
Updated bit 6 definition
Section 4.3, "MDIO Manageable
Device (MMD) Registers," on page 93
Added additional vendor specific MMD register
descriptions
SMSC LAN8740A/LAN8740Ai
Added pull-up to MDIO buffer type description
Changed “VIS/VOD8 (PU)” to “VIS/VO8 (PU)”
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Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology
Datasheet
Table 7.1 Customer Revision History (continued)
REVISION LEVEL
& DATE
Rev. 1.1
(05-10-13)
SECTION/FIGURE/ENTRY
CORRECTION
Section 4.3.11, "MAC Receive
Address A Register (RX_ADDRA)"
Added note
Section 4.3.12, "MAC Receive
Address B Register (RX_ADDRB)"
Added note
Section 4.3.13, "MAC Receive
Address C Register (RX_ADDRC)"
Added note
Chapter 5, "Operational
Characteristics," on page 124
Removed section “Power Sequence Timing”
Section 5.1, "Absolute Maximum
Ratings*," on page 124
Changed: Positive voltage on XTAL1/CLKIN, with
respect to ground from “VDDCR” to “+3.6V”
Section 5.3, Table 5.1, “Package
Thermal Parameters,” on page 125
Updated package thermal specification values
Section 5.4, "Power Consumption," on
page 126
Updated power numbers
Section 5.5, "DC Specifications," on
page 127
Changed VIHI max of ICLK Type Buffer from
“VDDCR” to “3.6”
Section 5.6, "AC Specifications," on
page 129
Removed two RMII notes at beginning of section
Section 5.6.3.1, "100 Mbps Internal
Loopback MII Timing," on page 133
Added new 100 Mbps internal loopback timing
section and diagram
Section 5.6.4, "RMII Interface Timing,"
on page 134
Rev. 1.0
(05-11-12)
Revision 1.1 (05-10-13)
Added note detailing CRS_DV behavior as both
carrier sense and data valid
Updated RMII timing table
Initial Release
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