AM79C984A

PRELIMINARY Am79C984A enhanced Integrated Multiport Repeater (eIMR™) DISTINCTIVE CHARACTERISTICS s Repeater functions comply with IEEE 802.3 Repeater Unit specifications s Four integral 10BASE-T transceivers with onchip filtering that eliminate the need for external filter modules on the 10BASE-T transmit-data (TXD) and receive-data (RXD) lines s One Reversible Attachment Unit Interface (RAUI™) port that can be used either as a standard IEEE-compliant AUI port for connection to a Medium Attachment Unit (MAU), or as a reversed port for direct connection to a Media Access Controller (MAC) s Low cost suitable for non-managed multiport repeater designs s Expandable to increase number of repeater ports with support for up to seven eIMR devices without the need for an external arbiter s All ports can be individually isolated (partitioned) in response to excessive collision conditions or fault conditions. s Full LED support for individual port status LEDs and network utilization LEDs s Programmable extended distance mode on the RXD lines, allowing connection to cables longer than 100 meters s Twisted Pair Link Test capability conforming to the 10BASE-T standard. The Link Test function and the transmission of Link Test pulses can be optionally disabled through the control port to allow devices that do not implement the Link Test function to work with the eIMR device. s Programmable option of automatic polarity detection and correction permits automatic recovery due to wiring errors s Full amplitude and timing regeneration for retransmitted waveforms s CMOS device with a single +5-V supply GENERAL DESCRIPTION The enhanced Integrated Multiport Repeater (eIMR) device is a VLSI integrated circuit that provides a system-level solution to designing non-managed multiport repeaters. The device integrates the repeater functions specified in Section 9 of the IEEE 802.3 standard and Twisted Pair Transceiver functions complying with the 10BASE-T standard. The eIMR device provides four Twisted Pair (TP) ports and one RAUI port for direct connection to a MAC. The total number of ports per repeater unit can be increased by connecting multiple eIMR devices through their expansion ports, hence, minimizing the total cost per repeater port. The device is fabricated in CMOS technology and requires a single +5-V supply. This document contains information on a product under development at Advanced Micro Devices. The information is intended to help you evaluate this product. AMD reserves the right to change or discontinue work on this proposed product without notice. Publication# 20650 Rev: B Amendment/0 Issue Date: January 1998 PRELIMINARY ORDERING INFORMATION Standard Products AMD standard products are available in several packages and operating ranges. The order number (Valid Combination) is formed by a combination of the elements below. Am79C984A J C \W ALTERNATE PACKAGING OPTION \W = Trimmed and formed in a tray TEMPERATURE RANGE C = Commercial (0˚C to +70˚C) PACKAGE TYPE J = 84-Pin Plastic Leaded Chip Carrier (PL 084) K = 100-Pin Plastic Quad Flat Pack (PQR100) SPEED OPTION Not Applicable DEVICE NUMBER/DESCRIPTION Am79C984A enhanced Integrated Multiport Repeater (eIMR) Valid Combinations Am79C984A JC, KC\W Valid Combinations Valid Combinations list configurations planned to be supported in volume for this device. Consult the local AMD sales office to confirm availability of specific valid combinations and to check on newly released combinations. 2 Am79C984A BLOCK DIAGRAM DI± CI± FIFO Preamble Phase Lock Loop FIFO CONTROL Jam Sequence TX MUX DO± AUI Port RX MUX Manchester Decoder RXD± TXD± Manchester Encoder TP Port 0 RXD± TXD± Partitioning Link Test RST Reset TP Port 3 eIMR Chip Control PRELIMINARY Am79C984A CLK Clock Gen Timers Expansion Port SELI[1:0] SELO ACK COL DAT JAM LED Interface LDA[4:0], LDB[4:0] LDGA, LDGB LDC[2:0] ACT[7:0] Test and Control Port SI SO SCLK AMODE 20650A-1 20650B-1 3 PRELIMINARY RELATED AMD PRODUCTS Part No. Am7990 Am7992B Am7996 Am79C90 Am79C98 Am79C100 Am79C981 Am79C982 Am79C987 Am79C988 Am79C900 Am79C940 Am79C960 Am79C961 Am79C961A Am79C965 Am79C970 Am79C970A Am79C974 Am79C983 Am79C985 Description Local Area Network Controller for Ethernet (LANCE) Serial Interface Adapter (SIA) IEEE 802.3/Ethernet/Cheapernet Transceiver CMOS Local Area Network Controller for Ethernet (C-LANCE) Twisted Pair Ethernet Transceiver (TPEX) Twisted Pair Ethernet Transceiver Plus (TPEX+) Integrated Multiport Repeater Plus (IMR+™) basic Integrated Multiport Repeater (bIMR™) Hardware Implemented Management Information Base (HIMIB™) Quad Integrated Ethernet Transceiver (QuIET™) Integrated Local Area Communications Controller (ILACC™) Media Access Controller for Ethernet (MACE™) PCnet™-ISA Single-Chip Ethernet Controller (for ISA bus) PCnet™-ISA+ Single-Chip Ethernet Controller for ISA (with Microsoft® Plug n’ Play® Support) PCnet™-ISA II Full Duplex Single-Chip Ethernet Controller for ISA PCnet™-32 Single-Chip 32-Bit Ethernet Controller PCnet™-PCI Single-Chip Ethernet Controller (for PCI bus) PCnet™-PCI II Full Duplex Single-Chip Ethernet Controller (for PCI bus) PCnet™-SCSI Combination Ethernet and SCSI Controller for PCI Systems Integrated Multiport Repeater 2 (IMR2™) enhanced Integrated Multiport Repeater Plus (eIMR+™) 4 Am79C984A PRELIMINARY TABLE OF CONTENTS DISTINCTIVE CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-29 GENERAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-29 ORDERING INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-30 STANDARD PRODUCTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-30 BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-31 RELATED AMD PRODUCTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-32 CONNECTION DIAGRAM (PL 084) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-35 CONNECTION DIAGRAM (PQR100) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-36 LOGIC SYMBOL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-37 LOGIC DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-37 PIN DESIGNATIONS (PL 084). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-38 Listed by Pin Number. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-38 PIN DESIGNATIONS (PQR100) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-39 Listed by Pin Number. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-39 PIN DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-40 AUI Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-40 Twisted Pair Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-40 Expansion Bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-40 Control Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-41 LED Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-41 Miscellaneous Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-41 FUNCTIONAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-43 Basic Repeater Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-43 Repeater Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-43 Signal Regeneration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-43 Jabber Lockup Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-43 Collision Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-43 Fragment Extension. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-43 Auto Partitioning/Reconnection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-43 Detailed Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-44 Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-44 AUI Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-44 TP Port Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-44 Twisted Pair Transmitters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-44 Twisted Pair Receivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-44 Link Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-45 Polarity Reversal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-45 Visual Status Monitoring (LED) Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-45 Network Activity Display. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-46 Expansion Bus Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-48 Internal Arbitration Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-48 IMR+ Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-48 Control Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-49 Command/Response Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-50 Control Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-50 SET (Write Commands) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-52 Chip Programmable Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-52 Alternate AUI Partitioning Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-52 Alternate TP Partitioning Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-52 AUI Port Disable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-52 AUI Port Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-52 TP Port Disable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-52 TP Port Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-52 Disable Link Test Function (Per TP port) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-52 Enable Link Test Function (Per TP port) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-52 Disable Link Pulse (Per TP Port) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-52 Am79C984A 5 PRELIMINARY Enable Link Pulse (Per TP Port). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-52 Disable Automatic Receiver Polarity Reversal (Per TP Port) . . . . . . . . . . . . . . . . . 1-53 Enable Automatic Receiver Polarity Reversal (Per TP Port) . . . . . . . . . . . . . . . . . 1-53 Disable Receiver Extended Distance Mode (Per TP Port) . . . . . . . . . . . . . . . . . . . 1-53 Enable Receiver Extended Distance Mode (Per TP Port) . . . . . . . . . . . . . . . . . . . 1-53 Disable Software Override of LEDs 5 (Per Port - AUI and TP, Global) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-53 Enable Software Override of Bank A LEDs (Per Port - AUI and TP, Global) . . . . . 1-53 Enable Software Override of Bank B LEDs (Per Port - AUI and TP, Global) . . . . . 1-54 Software Override of LED Blink Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-54 GET (Read Commands) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-54 AUI Port(s) Status. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-54 Alternate AUI Port(s) Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-54 TP Port Partitioning Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-54 Bit Rate Error Status of TP Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-54 Link Test Status of TP ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-55 Receive Polarity Status of TP Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-55 MJLP Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-55 Version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-55 SYSTEMS APPLICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-55 eIMR to TP Port Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-55 Twisted Pair Transmitters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-55 Twisted Pair Receivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-55 MAC Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-57 Internal Arbitration Mode Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-57 IMR+ Mode External Arbitration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-57 Visual Status Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-59 ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-60 OPERATING RANGES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-60 DC CHARACTERISTICS over operating ranges unless otherwise specified . . . . . . . . . . . . . . . . . 1-60 SWITCHING CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-62 KEY TO SWITCHING WAVEFORMS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-64 SWITCHING WAVEFORMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-64 SWITCHING TEST CIRCUIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-69 6 Am79C984A PRELIMINARY CONNECTION DIAGRAM (PL 084) RXD3– RXD3+ RXD2– RXD2+ RXD1– RXD1+ RXD0– RXD0+ VDD TXD3– TXD3+ AVSS TXD2– TXD2+ VDD REXT AVSS DI+ DI– VDD CI+ CI– AVSS DO+ DO– AMODE VDD DVSS VDD VDD VDD RST CLK DVSS SELI_0 SELI_1 11 10 9 8 7 6 5 4 3 2 1 84 83 82 81 80 79 78 77 76 75 74 12 13 73 72 14 71 15 70 16 17 69 68 18 67 19 66 20 21 65 eIMR 64 22 Am79C984A 63 23 62 24 61 25 60 26 27 59 58 28 57 29 56 30 55 31 54 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 SELO COL DVSS ACK DAT VDD JAM NC DVSS SI SO SCLK VDD ACT0 ACT1 ACT2 DVSS ACT3 ACT4 ACT5 ACT6 TXD1– TXD1+ AVSS TXD0– TXD0+ VDD LDC2 LDC1 LDC0 VDD LDGB LDGA LDB4 DVSS LDA4 LDB3 LDA3 DVSS LDB2 LDA2 VDD LDB1 LDA1 DVSS LDB0 LDA0 ACT7 20650A-2 20650B-2 Am79C984A 7 PRELIMINARY CONNECTION DIAGRAM (PQR100) RXD3– NC NC NC REXT AVSS DI+ DI– VDD CI+ CI– AVSS DO+ DO– AMODE VDD DVSS VDD VDD VDD RST NC CLK DVSS SELI_0 SELI_1 NC NC NC SELO 100 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81 RXD3+ RXD2– NC RXD2+ RXD1– RXD1+ RXD0– RXD0+ VDD TXD3– TXD3+ AVSS TXD2– TXD2+ VDD TXD1– TXD1+ AVSS TXD0– TXD0+ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 eIMR Am79C984A 80 79 78 77 76 75 74 73 72 71 70 69 68 67 66 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51 VDD NC NC NC LDC2 LDC1 LDC0 VDD LDGB LDGA LDB4 DVSS LDA4 LDB3 LDA3 DVSS LDB2 LDA2 VDD LDB1 LDA1 NC DVSS LDB0 LDA0 ACT7 NC NC NC ACT6 COL DVSS NC ACK DAT VDD JAM NC DVSS SI SO SCLK VDD ACT0 ACT1 ACT2 DVSS ACT3 ACT4 ACT5 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 20650B-3 8 Am79C984A PRELIMINARY LOGIC SYMBOL V DD Expansion Port DAT JAM ACK COL SELO SELI[1:0] TXD+ TXD– RXD+ RXD– DO+ DO– DI+ DI– CI+ CI– Twisted Pair Ports (4 Ports) Test and Control Port SI Am79C984 SO SCLK AMODE LDA[4:0], LDB[4:0] LDGA, LDGB LDC[2:0] ACT[7:0] CLK RST DVSS AVSS AUI LED Interface 20650A-4 20650B-4 LOGIC DIAGRAM AUI LED Port Control Port Repeater State Machine Expansion Port Twisted Pair Port 0 Twisted Pair Port 3 20650A-5 20650B-5 Am79C984A 9 PRELIMINARY PIN DESIGNATIONS (PL 084) Listed by Pin Number Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Pin Name TXD3+ TXD3VDD RXD0+ RXD0RXD1+ RXD1RXD2+ RXD2RXD3+ RXD3REXT AVSS DI+ DIVDD CI+ CIAVSS DO+ DOPin No. 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 Pin Name AMODE VDD DVSS VDD VDD VDD RST CLK DVSS SELI_0 SELI_1 SELO COL DVSS ACK DAT VDD JAM NC DVSS SI Pin No. 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 Pin Name SO SCLK VDD ACT0 ACT1 ACT2 DVSS ACT3 ACT4 ACT5 ACT6 ACT7 LDA0 LDB0 DVSS LDA1 LDB1 VDD LDA2 LDB2 DVSS Pin No. 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 Pin Name LDA3 LDB3 LDA4 DVSS LDB4 LDGA LDGB VDD LDC0 LDC1 LDC2 VDD TXD0+ TXD0AVSS TXD1+ TXD1VDD TXD2+ TXD2AVSS 10 Am79C984A PRELIMINARY PIN DESIGNATIONS (PQR100) Listed by Pin Number Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Notes: 1. Pin 40 has a bonding option depending on internal device name. 2. NC = No Connection. Pin Name RXD3NC NC NC REXT AVSS DI+ DIVDD CI+ CIAVSS DO+ DOAMODE VDD DVSS VDD VDD VDD RST NC CLK DVSS SELI_0 Pin No. 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 Pin Name SELI_1 NC NC NC SELO COL DVSS NC ACK DAT VDD JAM NC DVSS SI SO SCLK VDD ACT0 ACT1 ACT2 DVSS ACT3 ACT4 ACT5 Pin No. 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 Pin Name ACT6 NC NC NC ACT7 LDA0 LDB0 DVSS NC LDA1 LDB1 VDD LDA2 LDB2 DVSS LDA3 LDB3 LDA4 DVSS LDB4 LDGA LDGB VDD LDC0 LDC1 Pin No. 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 Pin Name LDC2 NC NC NC VDD TXD0+ TXD0AVSS TXD1+ TXD1VDD TXD2+ TXD2AVSS TXD3+ TXD3VDD RXD0+ RXD0RXD1+ RXD1RXD2+ NC RXD2RXD3+ Am79C984A 11 PRELIMINARY PIN DESCRIPTION AUI Port DI+, DI– Data In Differential Input DI± are differential, Manchester receiver pins. The signals comply with IEEE 802.3, Section 7. DO+, DO– Data Out Differential Output DO± are differential, Manchester output driver pins. The signals comply with IEEE 802.3, Section 7. CI+, CI– Collision Input Differential Input/Output CI± are differential, Manchester I/O signals. As an input, CI is a collision-receive indicator. As an output, CI generates a 10-MHz signal if the eIMR device senses a collision. state of the DAT pin is used in conjunction with JAM to indicate a single port (DAT =1) or multiport (DAT=0) collision. JAM is in the high-impedance state if neither the SEL nor ACK signal is asserted. It is recommended that JAM be pulled up or down via a high value resistor. SELI0-1 Select In Input, Active LOW When the expansion bus is configured for Internal Arbitration mode, these signals indicate that another eIMR device is active; SELI0 or SELI1 is driven by SELO from the upstream device. At reset, SELI0 selects between the Internal Arbitration mode and the IMR+ mode of the expansion bus; a HIGH selects the Internal Arbitration mode and a LOW selects the IMR+ mode. SELI_1 X X SELI_0 1 0 Arbitration Mode Internal IMR+ Twisted Pair Ports TXD+0-3, TXD–0-3 Transmit Data Differential Output TXD± are 10BASE-T port differential drivers (4 ports). RXD+0-3, RXD–0-3 Receive Data Differential Input RXD± are 10BASE-T port differential receive inputs (4 ports). SELO Select Out Output, Active LOW If the expansion bus is configured for Internal Arbitration mode, an eIMR device drives this pin LOW when it is active or when either of its SELI0-1 pins is LOW. An active eIMR device is defined as having one or more ports receiving or colliding and/or is still transmitting data from the internal FIFO, or extending a packet to the minimum of 96 bit times. When the expansion bus is configured for IMR+ mode, SELO is active when the eIMR device is active (acquiring the functionality of the REQ pin on the Am79C971 IMR+ device). ACK Acknowledge Input/Output, Active LOW, Open Drain This signal is asserted to indicate that an eIMR device is active. It also signals to the other eIMR devices the presence of a valid collision status on the JAM line and valid data on the DAT line. When the eIMR device is configured for Internal Arbitration mode, ACK is an I/O, and must be pulled to VDD via a minimum equivalent resistance of 1 kΩ. When the eIMR device is configured for IMR+ mode, ACK is an input driven by an external arbiter. COL Collision Input/Output, Active LOW, Open Drain When asserted, COL indicates that more than one eIMR device is active. Each eIMR device generates the Collision Jam sequence independently. When the eIMR device is configured for Internal Arbitration mode, COL is Expansion Bus DAT Data Input/Output/3-State If the SELO and ACK pins are asserted during noncollision conditions, the eIMR device drives NRZ data onto the DAT line, regenerating the preamble if necessary. During a collision, when JAM is HIGH, DAT is used to differentiate between single-port (DAT=1) and multiport (DAT=0) collisions. DAT is an output when ACK is asserted and the eIMR device’s ports are active; DAT is an input when ACK is asserted and the ports are inactive. If ACK is not asserted, DAT is in the high-impedance state. It is recommended that DAT be pulled up or down via a high value resistor. JAM Jam Input/Output/3-State The active eIMR device drives JAM HIGH, if it detects a collision condition on one or more of its ports. The 12 Am79C984A PRELIMINARY an I/O and must be pulled to VDD via a minimum equivalent resistance of 1 kΩ. When the eIMR device expansion port is configured for IMR+ mode, COL is an input driven by an external arbiter. multiple-eIMR configuration, LDGA from each of the eIMR devices can be tied together to drive a single global LED in Bank A. LDGB Global LED Driver, Bank B Output, Open Drain LDGB is the Global LED driver for LED Bank B. The signal represents global CRS or JAB conditions. In a multiple eIMR configuration, LDGB from each of the eIMR devices can be tied together to drive a single global LED in Bank B. LDC0-2 LED Control Input These pins select the attributes that will be displayed on LDA0-4, LDB0-4, LDGA, and LDGB. If an LED is programmed to display two attributes, the attribute associated with the periodic blink takes precedence. ACT0-7 Activity Display Output These signals drive the activity LEDs, which indicate the percentage of network utilization. The display is updated every 250 ms. Control Port AMODE AUI Mode Input At reset, this pin sets the AUI port to either normal or reversed mode. If AMODE is LOW at the rising edge of RST, the AUI port is set to the normal mode; if AMODE is HIGH, the AUI port is set to the reversed mode. SCLK Serial Clock In Input Serial data (input or output) is clocked (in or out) on the rising edge of the signal on this pin. SCLK is asynchronous to CLK and can operate at frequencies up to 10 MHz. SI Serial In Input The SI pin is used as a test/control serial input port. Control commands are clocked in on this pin synchronous to SCLK input. At reset, SI sets the state of the Automatic Polarity Reversal function. If SI is HIGH at the rising edge of RST, Automatic Polarity Reversal is disabled. If SI is LOW at the rising edge of RST, Automatic Polarity Reversal is enabled. SO Serial Out Output The SO pin is used as a control command serial output port. Responses to control commands are clocked out on this pin synchronous to the SCLK input. Miscellaneous Pins RST Reset Input, Active LOW When RST is LOW, the eIMR device resets to its default state. On the rising (trailing) edge of RST, the eIMR also monitors the state of the SELI0-1, SI, and AMODE pins, to configure the operating mode of the device. In multiple eIMR systems, the falling (leading) edge of the RST signal must be synchronized to CLK. CLK Master Clock In Input This pin is a 20-MHz clock input. REXT External Reference Input This pin is used for an internal current reference. It must be tied to VDD via a 13-kΩ resistor with 1% tolerance. VDD Power Power Pin This pin supplies power to the device. LED Interface LDA0-4, LDB0-4 LED Drivers Output, Open Drain LDA0-4 and LDB0-4 drive LED Bank A and LED Bank B, respectively. LDA0 and LDB0 indicate the status of the AUI port; LDA1-4 and LDB1-4 indicate the status of the four TP ports. The port attributes monitored by LDA0-4 and LDB0-4 are programmed by three pins, LDC0-2. LDGA Global LED Driver, Bank A Output, Open Drain LDGA is the Global LED driver for LED Bank A. The signal represents global CRS or COL conditions. In a Am79C984A 13 PRELIMINARY AVSS Analog Ground Ground Pin This pin is the ground reference for the differential receivers and drivers. DVSS Digital Ground Ground Pin This pin is the ground reference for all the digital logic in the eIMR device. 14 Am79C984A PRELIMINARY FUNCTIONAL DESCRIPTION The Am79C984A eIMR device is a single-chip implementation of an IEEE 802.3/Ethernet repeater (or hub). It is offered with four integral 10BASE-T ports plus one RAUI port comprising the basic repeater. The eIMR device is also expandable, enabling the implementation of high port count repeaters based on several eIMR devices. The eIMR chip complies with the full set of repeater basic functions as defined in Section 9 of ISO 8802.3 (ANSI/IEEE 802.3c). The basic repeaters functions are summarized in the paragraphs below. times. This is referred to as MAU Jabber Lockup Protection (MJLP). The MJLP status for the eIMR device can be read through the Control Port, using the Get MJLP Status command. Collision Handling The eIMR device will detect and respond to collision conditions as specified in the IEEE 802.3 specification. Repeater configurations consisting of multiple eIMR devices also comply with the IEEE 802.3 specification, using status signals provided by the expansion bus. In particular, a repeater based on one or more eIMR devices will handle the transmit collision and one-port-left collision conditions correctly, as specified in Section 9 of the IEEE 802.3 specification. Fragment Extension If the total packet length received is less than 96 bits, including preamble, the eIMR device will extend the repeated packet length to 96 bits by appending a Jam sequence to the original fragment. Auto Partitioning/Reconnection Any of the TP ports or the AUI port can be partitioned if the duration or frequency of collisions becomes excessive. The eIMR device will continue to transmit data packets to a partitioned port, but will not respond, as a repeater, to activity on the partitioned port’s receiver. The eIMR device will monitor the port and reconnect it once certain criteria are met. The criteria for reconnection are specified by the IEEE 802.3 standard. In addition to the standard reconnection algorithm, the eIMR device implements an alternative reconnection algorithm, which provides a more robust partitioning function for the TP ports and/or AUI port. The eIMR device partitions each TP port and the AUI port separately and independently of other network ports. The eIMR device will partition an enabled network port if either of the following conditions occurs at that port: a. A collision condition exists continuously for more than 2048 bit times. (AUI port—SQE signal active; TP port—simultaneous transmit and receive). b. A collision condition occurs during each of 32 consecutive attempts to transmit to that port. In the AUI port, a collision condition is indicated by an active SQE signal. In a TP port, a collision condition is indicated when the port is simultaneously attempting to transmit and receive. Once a network port is partitioned, the eIMR device will reconnect that port, according to the selected reconnection algorithm, as follows: a. Standard reconnection algorithm—A data packet longer than 512-bit times (nominal) is transmitted or received by the partitioned port without a collision. Basic Repeater Functions The Am79C984A chip implements the basic repeater functions as defined by Section 9.5 of the ANSI/IEEE 802.3 specification. Repeater Function If any single network port senses the start of a valid packet on its receive lines, the eIMR device will retransmit the received data to all other enabled network ports (except when contention exists among any of the ports or when the receive port is partitioned). To allow multiple eIMR device configurations, the data will also be repeated on the expansion bus data line (DAT). Signal Regeneration When retransmitting a packet, the eIMR device ensures that the outgoing packet complies with the IEEE 802.3 specification in terms of preamble structure and timing characteristics. Specifically, data packets repeated by the eIMR device will contain a minimum of 56 preamble bits before the Start-of-Frame Delimiter. In addition, the eIMR restores the voltage amplitude of the repeated waveform to levels specified in the IEEE 802.3 specification. Finally, the eIMR device restores signal symmetry to repeated data packets, removing jitter and distortion caused by the network cabling. Jitter present at the output of the AUI port will be better than 0.5 ns; jitter at the TP outputs will be better than 1.5 ns. The start-of-packet propagation delay for a repeater set is the time delay between the first edge transition of a data packet on its input port to the first edge transition of the repeated packet on its output ports. The start-ofpacket propagation delay for the eIMR is within the specification given in Section 9.5.5.1 of the IEEE 802.3 standard. Jabber Lockup Protection The eIMR device implements a built-in jabber protection scheme to ensure that the network is not disabled by the transmission of excessively long data packets. This protection scheme causes the eIMR device to interrupt transmission for 96 bit-times if the device has been transmitting continuously for more than 65,536 bit Am79C984A 15 PRELIMINARY b. Alternative reconnection algorithm—A data packet longer than 512-bit times (nominal) is transmitted by the partitioned port without a collision. A partitioned port can also be reconnected by disabling and re-enabling the port. All TP ports use the same reconnection algorithm; either they must all use the standard algorithm, or they must all use the alternative reconnection algorithm. However, the reconnection algorithm for the AUI port is programmed independently from that of the TP ports. power is maintained to the eIMR device, a reset duration of only 4 µs is required. This allows the eIMR device to reset its internal logic. During reset, the eIMR registers are set to their default values. Also during reset, the eIMR device sets the output signals to their inactive state; that is, all analog outputs are placed in their idle state, no bidirectional signals are driven, all active-HIGH signals are driven LOW and all activeLOW signals are driven HIGH. In a multiple eIMR system, the reset signal must be synchronized to CLK. See Figure 10 in the Systems Applications section. The eIMR device also monitors the state of the SELI0-1, SI, and AMODE pins on the rising (trailing) edge of RST to configure the operating mode of the device. Table 1 summarizes the state of the eIMR chip following reset. Detailed Functions Reset The eIMR device enters the reset state when the reset (RST) pin is driven LOW. After the initial application of power, the RST pin must be held LOW for a minimum of 150 µs. If the RST pin is subsequently asserted while Table 1. eIMR States after Reset Function Active-LOW Outputs Active-HIGH Outputs SO Output DAT, JAM Transmitters (TP and AUI) Receivers (TP and AUI) AUI Partitioning/Reconnection Algorithm TP Partitioning/Reconnection Algorithm Link Test Functions for TP Ports Automatic Receiver Polarity Reversal Function State after Reset HIGH LOW HIGH HIGH IMPEDANCE IDLE ENABLED STANDARD ALGORITHM STANDARD ALGORITHM ENABLED, TP PORTS IN LINK FAIL DISABLED IF SI PIN IS HIGH ENABLED IF SI PIN IS LOW Pull Up/Pull Down No No No Either No Terminated N/A N/A N/A N/A AUI Port The AUI Port is fully compatible with the IEEE 802.3, Section 7 requirement for an AUI port. It has the signals associated with an AUI port: DO, DI, and CI. The AUI port has two modes of operation: normal and reverse. When configured for normal operation, the functionality is that of an AUI port on a MAC (CI is an input). When configured for reverse operation, the functionality is that of an AUI on a MAU (CI is an output). The mode of the AUI port is set during the trailing (rising) edge of the reset pulse, by the state of the AMODE pin. A LOW sets the AUI port to its normal mode (CI Input) and a HIGH sets the AUI port to its reversed (CI Output) mode. The eIMR device can be connected directly to a MAC through the AUI port. This requires that the AUI port be configured for reverse operation. Refer to the Systems Applications section for more details. TP Port Interface Twisted Pair Transmitters TXD is a differential twisted-pair driver. When properly terminated, TXD will meet the electrical requirements for 10BASE-T transmitters as specified in IEEE 802.3, Section 14.3.1.2. The TXD signal is filtered on the chip to reduce harmonic content per IEEE 802.3, Section 14.3.2.1 (10BASE-T). Since filtering is performed in silicon, TXD can connect directly to a standard transformer, thereby, eliminating the need for external filtering modules. Proper termination is shown in the Systems Applications section. Twisted Pair Receivers RXD is a differential twisted-pair receiver. When properly terminated, RXD will meet the electrical requirements for 10BASE-T receivers as specified in IEEE 802.3, Section 14.3.1.3. The receivers do not require 16 Am79C984A PRELIMINARY external filter modules. Proper termination is shown in the Systems Applications section. The receiver’s threshold voltage can be programmed to an extended-distance mode. In this mode, the differential receiver’s threshold is reduced to allow a longer cable than the 100 meters specified in the IEEE 802.3 standard. For programming details, refer to the Control Commands section. Link Test The integrated TP ports implement the Link Test function, as specified in the IEEE 802.3 10BASE-T standard. The eIMR device will transmit Link Test pulses to any TP port after that port’s transmitter has been inactive for more than 8 ms to 17 ms. Conversely, if a TP port does not receive any data packets or Link Test pulses for more than 65 ms to 132 ms and the Link Test function is enabled for that port, then that port will enter the link-fail state. The eIMR device will disable a port in link-fail state (i.e., disable repeater transmit and receive functions) until it receives either four consecutive Link Test pulses or a data packet. The Link Test function can be disabled via the eIMR control port on a port-by-port basis, to allow the eIMR device to operate with pre-10BASE-T networks that do not implement the Link Test function. When the Link Test function is disabled, the eIMR device will not allow the TP port to enter link-fail state, even if no Link Test pulses or data packets are being received. Note, however, that the eIMR device will always transmit Link Test pulses to all TP ports, regardless of whether or not the port is enabled, partitioned, in link-fail state, or has its Link Test function disabled. Separate control commands exist for enabling and disabling the transmission of Link Test pulses on a port-by-port basis. Polarity Reversal The TP ports can be programmed to receive data if a wiring error results in a data packet being received at a TP port with reversed polarity. This function will be enabled upon reception of a negative End Transmit Delimiter (ETD) or negative pulses and allows subsequent packets to be received with the correct polarity. The polarity-reversal function is executed once following reset or link-fail and can be programmed via the control port to be enabled or disabled on a port-by-port basis. The function may be enabled or disabled, following a reset, depending on the level of the SI signal on the rising edge of the RST pulse. Visual Status Monitoring (LED) Support The eIMR status port can be connected to LEDs to facilitate the visual monitoring of repeater port status. The status port has twelve output signals, LDA0-4, and LDB0-4, LDGA, and LDGB. LDA0-4 and LDB0-4 represent the four TP ports and AUI port. LDGA and LDGB are global indicators. Attributes that may be monitored are Carrier Sense (CRS), Collision (COL), Partition (PAR), Link Status (LINK), Loopback (LB), Port Disabled (DIS), and Jabber (JAB). Three control bits, LDC0-2, select the particular attributes to be displayed on the LEDs. Table 2 shows how the programming combinations for LDC0-2 control the attributes that will be monitored. Each LED drive pin (LDGA, LDGB, LDA0-4, and LDB0-4) has two states: Off and LOW. When none of the selected attributes are true, the driver is off and the diode is unlit. When an attribute is true, the driver is LOW, and the corresponding LEDs in Bank A or Bank B will be lit. Some of the settings (LDC2 = 1) include a blink function. This allows two attributes to be selected for a given state on the pin. As an example when LDC0-2 = 110, the LDA outputs relating to TP ports will be solidly lit when there is a link established at that port. However, whenever there is activity on a port, the corresponding LDA pin will switch on (LOW) and off at a period of 130 ms. Note that a partition on that port will also cause the pin to go LOW. On LDC settings that have two attributes for a state on a pin (blink or solid-on), the attribute causing the output to blink has priority. (Those attributes are shown in Table 2 with a blink period specified next to it.) If an attribute has no blink period specified, the LED indicates the attribute by being solidly lit. The LEDs can also be controlled via the control port. The Enable Software Override commands turn the LEDs on regardless of the attributes selected for display through the LDC setting. Enable Software Override of Bank A LEDs causes the LDA0-4 and LDGA pins to be driven LOW, and Enable Software Override of Bank B LEDs causes the LDB0-4 and LDGB pins to be driven LOW. The blink rate is set by the Software Override LED Blink Rate command. The periods are off, 512 ms, 1560 ms, or solid on. Am79C984A 17 PRELIMINARY Table 2. LED Attribute-Monitoring Program Options LED Control LDC2 LDC1 LDC0 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 Global LEDs LDGA LDGB CRS COL CRS COL CRS 260-ms blk COL CRS CRS COL 260-ms blk JAB COL COL TP LEDs LDA1-4 LDB1-4 LINK (Note 2) PAR LINK CRS Reserved (Note 5) Reserved (Note 5) LINK PAR CRS 260-ms blk COL 260-ms blk LINK (Note 3) PAR (Note 3) CRS 512-ms blk LINK PAR or DIS CRS 130-ms blk LINK (Note 4) PAR 1.56-s blk COL (Note 4) AUI LEDs LDA0 LB LB LDB0 PAR CRS CRS 260-ms blk (Note 3) CRS 512-ms blk CRS 130-ms blk (Note 4) PAR 1.56-s blk PAR COL 260-ms blk PAR (Note 3) PAR or DIS PAR (Note 4) Notes: 1. CRS = Carrier Sense, COL = Collision, JAB = Jabber, LINK = Link, LB = Loop Back, PAR = Partition, DIS = Port Disabled, blk = Blink (Number = period of Blink). 2. For the LDC0-2 setting of 000: If the port is partitioned, the LINK LED is off. 3. All LEDs blink 16 times at 260 ms per blink after reset. 4. All LEDs are on for approximately 4 seconds after reset. 5. LDC0-2 = ‘010’ and ‘011’ are undefined. LED software override is executed in two stages, by first issuing the blink rate (Software Override of LED Blink Rate) and then issuing the command to enable the particular port LEDs (Enable Software Override of Bank A/B LEDs). All port combinations selected for software override control will reference the blink rate last issued by the Software Override of the LED Blink Rate command. LDA0-4, LDB0-4, LDGA, and LDGB are open drain output drivers that sink 12 mA of current to turn on the LEDs. In a multiple eIMR configuration, the outputs from the global LED drivers (LDGA and LDGB) of each chip can be tied together to drive a single pair of global status LEDs. CRS and COL are extended to make it easier for visual recognition; that is, they will remain active for some time even if the corresponding condition has expired. Once carrier sense is active, CRS will remain active for a minimum of 4 ms. Once a collision is detected, COL is active for at least 4 ms. The exception to this rule is for selection LDC0-2 = 111. For this selection, COL is stretched to 100 µs. When LDC0-2 = 000 or LDC0-2 = 001, the loopback attribute (LB) for the AUI port is displayed on LDA0. LB is true when DO on the MAU is successfully looped back to DI on the AUI port. LB is false (off) if a loopback error is detected, or if the AUI port is disabled or in the reverse mode. Transmit carrier sense is sampled at the end of packet to determine the state of LB. The state of LB remains latched until carrier sense is sampled again for the next packet. The default/power-up state for LB is false (off). Figure 1 shows the recommended connection of LEDs. When LDA0-4, LDB0-4, LDGA, or LDGB are LOW, the LED lights. VDD eIMR LED Interface LDA[4:0] LDB[4:0] LDGA LDGB R Typical 20650B-6 20650A-6 Figure 1. Visual Monitoring Application—Direct LED Drive Network Activity Display The eIMR status port can drive up to eight LEDs to indicate the network-utilization level as a percentage of bandwidth. The status port uses eight dedicated outputs (ACT0-7) to drive a series of LEDs. The number of LEDs in the series that will be lit increases as the amount of network activity increases. ACT0 represents the lowest level of activity; ACT7 represents the highest. ACT0-7 are open-drain outputs that typically sink 12 mA of current to turn on the LEDs. See Figure 2. 18 Am79C984A PRELIMINARY VDD eIMR LED Interface ACT[0] ACT[1] ACT[2] ACT[3] ACT[4] ACT[5] ACT[6] ACT[7] 20650A-7 Figure 2. Network Activity Display Table 3 shows ACT0-7 as a function of the percentage of network utilization. The table uses a scale that is more sensitive at low utilization levels. 100% utilization represents the maximum number of events that could occur in a given window of time. The update rate and corresponding internal sampling window for ACT[7:0] is 250 ms. During this sampling window, a counter is used to count the number of times repeater transmit activity is TRUE. The counter uses a free-running clock which has the granularity to detect the minimum packet size of 96 bit times. Figure 3 shows the timing relationship between the sampling window, counting clock, and transmit activity. Table 3. Network Utilization Number of LEDs Lit by ACT7-0 8 7 6 5 4 3 2 1 Percentage Utilization >80% >64% >32% >16% >8% >4% >2% >1% latch data; update display; clear counter counter is active Sampling Window Counting Clock Xmit Activity 20650B-8 next counting cycle Figure 3. Activity Sampling Am79C984A 19 PRELIMINARY Expansion Bus Interface The eIMR device expansion bus allows multiple eIMR devices to be interconnected. The expansion bus supports two modes of operation: internal arbitration mode and IMR+ mode. The internal arbitration mode uses a modified daisy-chain scheme to eliminate the need for any external arbitration circuitry. The IMR+ mode maintains the full functionality of the IMR+ (Am79C981) expansion bus and benefits from minimum delays. In this mode, the eIMR device requires external circuitry to handle arbitration for control of the bus. The eIMR arbitration mode is determined at reset. This occurs on the trailing edge of RST according to the state of SELI0-1, as illustrated in Figure 4. Internal Arbitration Mode The internal arbitration mode uses a daisy-chain (cascade) configuration. SELI0-1 are arbitration inputs and SELO is the arbitration output. SELO goes LOW when there is activity on one or more of the eIMR ports, or a SELI input is LOW. The SEL lines are connected as shown in Figure 5. This technique allows activity indication to propagate down the chain to the end device. All unused SELI inputs must be tied to VDD. ACK and COL are global activity I/O pins. When the eIMR device senses activity, it drives ACK LOW. . ACK and COL are mutually exclusive. If an eIMR driving ACK senses COL LOW, the device will deassert ACK. DAT and JAM are synchronized to CLK. DAT is the repetition of data from any connected port (either TP or AUI port) encoded in NRZ format. JAM is an internal collision indicator. If JAM is HIGH, the active eIMR device has detected an internal collision across one or more of its ports. When this occurs, the DAT signal distinguishes between single-port collisions and multiport collisions. DAT = 1 indicates a single port collision; DAT = 0 indicates a multiport collision. The drive capabilities of the I/O signals on the expansion bus (DAT, JAM, ACK, and COL) are sufficient to allow seven eIMR devices to be connected together without the use of external transceivers or buffers. The maximum number of eIMR devices that can be daisy chained is limited by the propagation delay of the eIMR devices. In practice, the depth of the cascade is limited to three eIMR devices, thus allowing a maximum of seven eIMR devices connected together via this expansion bus as shown in Figure 5. The active device will not drive the data line, DAT, until one bit time (100 ns) after SELO goes LOW. This is to avoid a situation where two devices drive DAT simultaneously. IMR+ Mode In IMR+ mode, the expansion bus requires an external arbiter. The arbiter allows only one eIMR device to control the expansion bus. If more than one device attempts to take control, the arbiter terminates all access and signals a collision condition. In IMR+ mode, DAT and JAM retain the same functionality as in internal arbitration mode, but ACK and COL are inputs to the eIMR device, driven by the external arbiter. The arbiter should drive ACK LOW when exactly one eIMR device is active. It should drive COL when more than one eIMR device is active. SELO is an output from the eIMR device. It indicates that the eIMR device has an active port and is requesting access to the bus. When ACK is HIGH, DAT and JAM are in the highimpedance state. DAT and JAM go active when ACK goes LOW. Refer to the Systems Applications section (Figure 13) for the configuration of IMR+ mode of operation. RST SELI_0 Mode Selection SELI_1 X X SELI_0 1 0 Arbitration Mode Internal IMR+ 20650B-9 Figure 4. Expansion Bus Mode Selection An eIMR device drives COL LOW when it senses more than one device is active; that is, if the device has an active port AND a SELI input is LOW, OR both SELI inputs are LOW. In Boolean notation, the formula for COL is: COL = (Active port & (SELI1 + SELI0))+ (SELI1 & SELI0) where & represents the Boolean AND operation + represents the Boolean OR operation 20 Note: The IMR+ mode is recommended when arbitrating between multiple boards. . Am79C984A PRELIMINARY VDD 1kΩ SELI_0 SELI_1 ACK SELO SELI_0 SELI_1 ACK COL DAT JAM SELO SELI_0 SELI_1 ACK COL SELO DAT JAM COL DAT JAM SELI_0 SELI_1 ACK SELO SELI_0 SELI_1 ACK SELO SELI_0 SELI_1 ACK COL DAT JAM SELO SELI_0 SELI_1 ACK COL DAT JAM COL DAT JAM SELO 20650A-10 20650B-10 Figure 5. Internal Arbitration—eIMR Devices in Cascade Control Functions The eIMR device receives control commands in the form of byte-length data on the serial input pin, SI. If the eIMR device is expected to provide data in response to the command, it will send byte-length data to the serialoutput pin, SO. Both the input and output data streams are clocked with the rising edge of the SCLK signal. The byte-length data is in RS232 serial-data format; that is, one start bit followed by eight data bits. The externally generated clock at the SCLK pin may be either a free-running clock synchronized to the input bit patterns, or a series of individual transitions meeting the setup-and-hold times with respect to the input bit pattern. If the latter method is used, 20 SCLK clock transitions are required for control commands that produce SO data, and 14 SCLK clock transitions are required for control commands that do not produce SO data. Am79C984A COL DAT JAM 21 PRELIMINARY Command/Response Timing Figure 6 shows the command/response timing. At the . end of a GET command, the eIMR device waits two SCLK cycles and then transmits the response on SO. SCLK SI ST D0 D1 D2 D3 D4 D5 D6 D7 SO ST D0 D1 D2 D3 D4 D5 D6 D7 20650A-11 20650B-11 Figure 6. Control Get Command/Response Control Commands The following section details the operation of each control commands available in the eIMR device. In all cases, the individual bits in each command are shown with the most-significant bit (bit 7) on the left and the least-significant bit (bit 0) on the right. Table 4 and Table 5 show a summary of default states and a summary of control commands, respectively. Table 4. Summary of Default States after Reset eIMR Programmable Option—S AUI Partitioning Algorithm TP Partitioning Algorithm AUI/TP Port Link Test Link Pulse Automatic Receiver Polarity Reversal Extended Distance Mode Blink Rate Software Override of LEDs Off Normal Normal Enabled Enabled Enabled State of SI at reset Disabled Off Disabled Note: Data is transmitted and received on the serial data lines least-significant bit first and most-significant bit last. 22 Am79C984A PRELIMINARY Table 5. Control Port Command Summary Commands SI Data SO Data Set (Write Commands) eIMR Chip Programmable Options Alternate AUI Partitioning Algorithm Alternate TP Partitioning Algorithm AUI Port Disable AUI Port Enable TP Port Disable TP Port Enable Disable Link Test Function (per TP port) Enable Link Test Function (per TP port) Disable Link Pulse (per TP port) Enable Link Pulse (per TP port) Disable Automatic Receiver Polarity Reversal (per TP port) Enable Automatic Receiver Polarity Reversal (per TP port) Disable Receiver Extended Distance Mode (per TP port) Enable Receiver Extended Distance Mode (per TP port) Disable Software Override of LEDs (per Port - AUI & TP) Enable Software Override of Bank A LEDs (per Port - AUI & TP, Global) Enable Software Override of Bank B LEDs (per Port - AUI & TP, Global) Software Override LED Blink Rate Get (Read Commands) AUI Port Status (B, S, and L Cleared) AUI Port Status (B Cleared) AUI Port Status (S, L, Cleared) AUI Port status (None Cleared) TP Port Partitioning Status Bit Rate Error Status of TP Ports Link Test Status of TP Ports Receive Polarity Status of TP Ports MJLP Status Version 0000 10S0 0001 1111 0001 0000 0010 1111 0011 1111 0010 00## 0011 00## 0100 00## 0101 00## 0100 10## 0101 10## 0110 00## 0111 00## 0110 10## 0111 10## 1001 #### 1011 #### 1100 #### 1110 1### 1000 1111 1000 1101 1000 1011 1000 1001 1000 0000 1010 0000 1101 0000 1110 0000 1111 0000 1111 1111 PBSL 0000 PBSL 0000 PBSL 0000 PBSL 0000 0000 C3..C0 0000 E3..E0 0000 L3..L0 0000 P3..P0 M000 0000 0000 0011 Am79C984A 23 PRELIMINARY SET (Write Commands) Chip Programmable Option SI Data SO Data 0000 10S0 None AUI Por t Enable SI SO Data 0011 1111 None This command enables the AUI port. The eIMR chip programmable option can be enabled (or disabled) by setting (or resetting) the S bit in the command string. TP Por t Disable SI Data SO Data 0010 00## None S AUI SQE Test Mask Setting this bit allows the eIMR chip to ignore activity on the CI signal pair, during the SQE test window, following a transmission on the AUI port. Enabling this function does not prevent the reporting of this condition by the eIMR device. The two functions operate independently. The SQE Test Window, as defined in IEEE 802.3 (Section 7.2.2.2.4) is from 6 bit times to 34 bit times (0.6 µs to 3.4 µs). This includes the delay introduced by a 50meter AUI. CI activity that occurs outside this window is not ignored and is treated as a true collision. This command disables the TP port designated by the two least-significant bits of the command byte. Subsequently, the eIMR chip will ignore all inputs to the designated port and will not transmit a DAT or JAM pattern on that port. Disabling the TP port also sets the partitioning state machine of that port to the idle state. Therefore, a partitioned port can be reconnected by first disabling the port and then enabling it. TP Por t Enable SI Data SO Data 0011 00## None Alternate AUI Par titioning Algorithm SI Data SO Data 0001 1111 None This command enables the TP port designated by the two least-significant bits of the command byte. Disable Link Test Function (Per TP por t) SI Data SO Data 0100 00## None Invoking this command sets the partition/reconnection scheme for the AUI port to the alternate (transmit-only) reconnection algorithm. To return the AUI port to the standard (transmit or receive) reconnection algorithm, it is necessary to reset the eIMR device. The standard partitioning algorithm is selected on reset. Alternate TP Par titioning Algorithm SI Data SO Data 0001 0000 None This command disables the Link Test function of the TP port designated by the two least-significant bits of the command data. As a consequence of this, the port will no longer be disconnected if it fails the Link Test. If a port has the Link Test disabled, reading the Link Test Status indicates a ‘Link Pass’. Enable Link Test Function (Per TP por t) SI Data SO Data 0101 00## None Invoking this command sets the partition/reconnection scheme for the TP ports to the alternate (transmit-only) reconnection algorithm. To return the TP ports to the standard (transmit or receive) reconnection algorithm, it is necessary to reset the eIMR device. The standard partitioning algorithm is selected on reset. AUI Por t Disable SI SO Data 0010 1111 None This command enables the Link Test function of the TP port designated by the two least-significant bits of the command data. As a consequence of this, the port is disconnected if it fails the Link Test. Disable Link Pulse (Per TP Por t) SI Data SO Data 0100 10## None This command disables the AUI port. Subsequently, the eIMR chip will ignore all inputs to this port and will not transmit a DAT or JAM pattern on the AUI port. Disabling the AUI port also sets the partitioning state machine of the AUI port to the idle state. Therefore, a partitioned port can be reconnected by first disabling the AUI port and then enabling the AUI port. This command disables the transmission of the Link pulse on the TP port designated by the two leastsignificant bits of the command byte. Enable Link Pulse (Per TP Por t) SI Data SO Data 0101 10## None This command enables the transmission of the Link pulse on the TP port designated by the two leastsignificant bits of the command byte. 24 Am79C984A PRELIMINARY Disable Automatic Receiver Polarity Reversal (Per TP Por t) SI Data SO Data 0110 00## None Disable Software Override of LEDs (Per Por t - AUI and TP, Global) SI Data SO Data 1001 #### None This command disables the Automatic Receiver Polarity Reversal function for the TP port designated by the two least-significant bits in the command byte. If this function is disabled on a TP port receiving with reversed polarity (due to a wiring error), the TP port will fail the Link Test due to the incorrect polarity of the received Link pulses. The state of Automatic Polarity Reversal function is set by SI on reset. If SI is HIGH at the rising edge of RST, the eIMR device disables Automatic Polarity Reversal. If SI is LOW at the rising edge of RST, the eIMR device enables Automatic Polarity Reversal. This command disables Software Override of the Port LEDs. Individual LEDs and combinations of LEDs can be selected via the lower four bits of the command byte as follows: Enable Automatic Receiver Polarity Reversal (Per TP Por t) SI Data SO Data 0111 00## None #### 0000-0011 0100-0111 1000 1001 1010 1011 1100 1101 1110 1111 Por t(s) affected TP0 - TP3 Reserved AUI port Reserved Reserved All TP ports All ports Global Reserved Reserved This command enables the Automatic Receiver Polarity Reversal function for the TP port designated by the two least-significant bits in the command byte. If enabled in a TP port, the eIMR chip will automatically invert the polarity of that port’s receiver circuitry if the TP port is detected as having reversed polarity (due to wiring error). After reversing the receiver polarity, the TP port could then receive subsequent (reverse polarity) packets correctly. Following command execution, the attributes displayed on the LEDs will be determined by LDC0-2. Software Override of LEDs is disabled after reset. Enable Software Override of Bank A LEDs (Per Por t AUI and TP, Global) SI Data SO Data 1011 #### None Disable Receiver Extended Distance Mode (Per TP Por t) SI Data SO Data 0110 10## None This command forces the LEDs in Bank A to blink. Individual LEDs and combinations of LEDs can be selected via the lower four bits of the command byte as follows: This command disables the Receiver Extended Distance Mode and restores the RXD circuit of the transceiver to normal squelch levels for the TP port driver designated by the two least-significant bits of the command data. Enable Receiver Extended Distance Mode (Per TP Por t) SI Data SO Data 0111 10## None #### 0000-0011 0100-0111 1000 1001 1010 1011 1100 1101 1110 1111 Por t(s) affected TP0 - TP3 Reserved AUI port Reserved Reserved All TP ports All ports Global Reserved Reserved This command modifies the RXD circuit of the transceiver for the TP port driver designated by the two leastsignificant bits of the command data. The RXD squelchthreshold value is lowered to accommodate signal attenuation associated with lines longer than 100 meters. At reset, Receiver Extended Distance Mode is disabled and the RXD circuit defaults to normal squelch-threshold values. The designated LED driver(s) will switch between LOW and ‘off’ at the rate set by the Software Override Blink Rate command. Enable Software Override of Bank A LEDs references the blink rate last issued and overrides any other attribute specified by LDC0-2. Software Override of LEDs is disabled after reset. Am79C984A 25 PRELIMINARY Enable Software Override of Bank B LEDs (Per Por t AUI and TP, Global) SI Data SO Data 1100 #### None B Bit Rate Error This bit is set to ‘1’ if there is an instance of FIFO overflow or underflow. The bit is cleared when the eIMR device is read. This command forces the LEDs in Bank B to blink. Individual LEDs and combinations of LEDs can be selected via the lower four bits of the command byte as follows: S SQE Test Status This bit is set to ‘1’ if the SQE test error is detected by the eIMR chip. The bit is cleared when the status is read. #### 0000-0011 0100-0111 1000 1001 1010 1011 1100 1101 1110 1111 Por t(s) affected TP0 - TP3 Reserved AUI port Reserved Reserved All TP ports All ports Global Reserved Reserved L Loopback Error The MAU attached to the AUI port is required to loopback data transmitted to DO onto the DI circuit. If the loopback carrier is not detected by the eIMR device, this bit is set to ‘1’. This bit is cleared when the status is read. Alternate AUI Por t(s) Status There are three further variations of the AUI Port Status Command allowing selective clearing of a combination of B,S, and L bits. These are the following: The designated LED driver(s) will switch between LOW and ‘off’ at the rate set by the Software Override of LED Blink Rate command. Enable Software Override of Bank B LEDs references the blink rate last issued and overrides any other attribute specified by LDC0-2. Software Override of LEDs is disabled after reset. Alternate 1: B is not cleared, S and L are Cleared SI Data SO Data 1000 1011 PBSL 0000 Alternate 2: S and L are not cleared, B is Cleared SI Data SO Data 1000 1101 PBSL 0000 Software Override of LED Blink Rate SI Data SO Data 1110 1### None Alternate 3: None of S, B, and L are Cleared SI Data SO Data SI Data SO Data 1000 1001 PBSL 0000 1000 0000 0000 P3..P0 This command sets the blink period of the LEDs with Software Override enabled. The duty cycle is 50%. This command defaults to ‘off’ at reset. TP Por t Par titioning Status Setting 1110 1000 1110 1001 1110 1010 1110 1011 Blink Period Off 512 ms 1560 ms Solid On Pn = 0 TP Port Partitioned TP port Connected Pn = 1 where n is a port number in the range 0–3. The response to this command gives the partitioning status of all four TP ports. If a port is disabled, reading its partitioning status will indicate that it is connected. These settings apply to the blink rate for both Bank A and Bank B. This command must precede the Enable Software Override of Bank A/B LEDs command. All LED combinations selected for Software Override will reference the blink rate last issued. Bit Rate Error Status of TP Por ts SI Data SO Data 1010 0000 0000 E3..E0 GET (Read Commands) AUI Por t(s) Status SI Data SO Data 1000 1111 PBSL 0000 En = 0 No Error En = 1 FIFO Overflow where n is a port number in the range 0–3. The response to this command gives the bit-rate-overflow or underflow (data rate mismatch) condition of all the TP ports. A 1 indicates that the FIFO has overflowed or underflowed due to the amount of data received by the corresponding port. The combined AUI status of the eIMR device allows a single instruction to be used to monitor the AUI port. The four local status bits are: P Partitioning Status This bit is ‘0’ if the AUI port is partitioned and ‘1’ if the AUI port is connected. 26 Am79C984A PRELIMINARY Link Test Status of TP por ts SI Data SO Data 1101 0000 0000 L3..L0 SYSTEMS APPLICATIONS eIMR to TP Port Connection The eIMR device provides a system solution to designing non-managed multiport repeaters. The eIMR device connects directly to AC coupling modules for a 10BASE-T hub. Figure 7 shows the simplified connection. Ln = 0 TP Port n in Link Test Failed Ln = 1 TP port n in Link Test Passed where n is a port number in the range 0–3. The response to this command gives the Link Test status of all the TP ports. A disabled port continues to report Link Test status. Re-enabling the port causes the port to be placed in the Link Test Fail state. Twisted Pair Transmitters TXD signals need to be properly terminated to meet the electrical requirement for 10BASE-T transmitters. Proper termination is shown in Figure 8 which consists of a 110-Ω resistor and a 1:1 transformer. The load is a twistedpair cable that meets IEEE 802.3, Section 14.4 specifications. The cable is terminated at the opposite end by 100 Ω. Receive Polarity Status of TP Por ts SI Data SO Data 1110 0000 0000 P3......P0 Pn = 0 TP Port n Polarity Correct Pn = 1 TP port n Polarity Reversed where n is a port number in the range 0–3. The response to this command gives the Received Polarity status of all the TP ports. If the polarity is detected as reversed for a TP port, then the eIMR device will set the appropriate bit in this command’s result only if the Polarity Reversal Function is enabled for that port. Twisted Pair Receivers RXD signals need to be properly terminated to meet the electrical requirements for 10BASE-T receivers. Proper termination is shown in Figure 9. Note that the receivers do not require external filter modules. MJLP Status SI Data SO Data 1111 0000 M000 0000 Each eIMR device contains an independent MAU Jabber Lock Up Protection timer. The timer is designed to inhibit the transmit function of the eIMR device if it has been transmitting continuously for more than 65536 bit times. This bit remains set and is only cleared when the MJLP status is read using this command. Version SI Data SO Data 1111 1111 0000 0011 The response to this command gives the version of the eIMR device. 0011 was chosen to help distinguish the eIMR device from the IMR (Am79C980) and the IMR+ (Am79C981) devices. Am79C984A 27 PRELIMINARY eIMR TXD0+ TXD0– RXD0+ RXD0– 110 Ω 100 Ω 1:1 TP Connector 1:1 TP Connector TXD1+ TXD1– RXD1+ RXD1– 110 Ω 100 Ω 1:1 1:1 TP Connector TXD2+ TXD2– RXD2+ RXD2– 110 Ω 100 Ω 1:1 1:1 TP Connector TXD3+ TXD3– RXD3+ RXD3– 110 Ω 100 Ω 1:1 1:1 RST CLK 20650A-12 Figure 7. Simplified 10BASE-T Connection TXD+ 110Ω TXD- 1:1 Twisted Pair 100Ω 20650A-13 20650B-13 Figure 8. TXD Termination RXD+ 1:1 Twisted Pair 100Ω 100Ω RXD– 20650A-14 20650A-14 20650B-14 Figure 9. RXD Termination 28 Am79C984A PRELIMINARY MAC Interface The eIMR device can be connected directly to a MAC through the AUI port. This requires that the AUI port be configured in the reverse mode and connected as shown in Figure 10a. Notice that DI is connected to DO of the MAC and DO is connected to DI of the MAC, because the reverse configuration only affects CI. Where CI is an input in the normal mode, in the reverse mode, CI is an output. Figure 10b shows the normal AUI configuration for reference. Am79C940 DO+ DO– 40 Ω DI+ DI– 40 Ω CI+ CI– 40 Ω 0.1 µF 40 Ω 40 Ω 40 Ω eIMR DI+ DI– Am7996 DI+ DI– 40 Ω 40 Ω 1:1 eIMR DI+ DI– DO+ DO– DO+ DO– 40 Ω 40 Ω 1:1 DO+ DO– 0.1 µF CI+ CI– CI+ CI– 1:1 CI+ CI– 40 Ω 0.1 µF 39 – 150 Ω 0.1 µF –9 V 40 Ω 0.1 µF a) Reverse Mode (with MAC) b) Normal Mode (with MAU) 20650B-15 20650A-16 Figure 10. AUI Port Interconnections Internal Arbitration Mode Connection The internal arbitration mode uses a modified daisychain scheme to eliminate the need for any external arbiter. In this mode, ACK and COL need to be pulled up through a minimum resistance of 1 kΩ. The DAT and JAM pins also need to be pulled down via a high value resistor. Refer to Figure 11. IMR+ Mode External Arbitration The IMR+ mode maintains the full functionality of AMD’s IMR+ (Am79C981) device’s expansion bus. In this mode, the eIMR device requires external circuitry to handle arbitration for control of the bus. Figure 12 shows the configuration for the IMR+ mode of operation. Am79C984A 29 PRELIMINARY VDD (Note: In a multiple eIMR system, the reset signal must be synchronized to CLK.) 74LS74 RST D ACK COL JAM DAT Q D Q SELI_0 SELI_1 RST CLK eIMR SELO SELI_0 SELI_1 RST CLK JAM DAT eIMR SELO ACK COL Q PC Q PC 20 MHz OSC VDD ~1 kΩ SELI_0 SELI_1 RST CLK JAM DAT eIMR SELO COL ACK 1 kΩ ~1 kΩ VDD 20650B-16 Figure 11. eIMR Internal Arbitration Mode Connection eIMR SELI_0 SELO SELI_1 DAT JAM ACK COL eIMR SELI_0 SELO SELI_1 DAT JAM ACK COL eIMR SELI_0 SELO SELI_1 DAT JAM ACK COL 1 kΩ COL ACK SEL1 SEL2 SEL3 Arbiter GCOL 20650B-17 Figure 12. IMR+ Mode External Arbitration 30 Am79C984A PRELIMINARY Visual Status Display LDA/B[4:0] and LDGA/B provide visual status indicators for the eIMR. LDA/B[4:0] displays Link, Carrier Sense, Collision, and Partition information for the TP and AUI ports. LDGA/B display global Carrier Sense, Collision, and Jabber information. In a multiple eIMR configuration, the global LED drivers (LDGA/B) from each chip can be tied together to drive a single pair of global status LEDs. The open drain output of these drivers facilitate this configuration. Refer to Figure 13. VDD LDA[4:0] LDB[4:0] LDGA LDGB LDA[4:0] LDB[4:0] LDGA LDGB 20650B-18 20650A-19 Figure 13. Visual Status Display Connection Am79C984A 31 PRELIMINARY ABSOLUTE MAXIMUM RATINGS Storage Temperature . . . . . . . . . . –65° C to +150° C Ambient Temperature Under Bias . . . . 0° C to +70° C Supply Voltage referenced to AVSS or DVSS (AVDD, DVDD) . . . . . . . –0.3 V to +6.0 V OPERATING RANGES Commercial (C) Devices Temperature (TA) . . . . . . . . . . . . . . . . . 0° C to +70° C Supply Voltages (VDD) . . . . . . . . . . . . . . . . . +5 V ±5% Stresses above those listed under ABSOLUTE MAXIMUM RATINGS may cause permanent device failure. Functionality at or above these limits is not implied. Exposure to Absolute Maximum Ratings for extended periods may affect reliability. Programming conditions may differ. Operating ranges define those limits between which the functionality of the device is guaranteed. DC CHARACTERISTICS over operating ranges unless otherwise specified Parameter Symbol Digital I/O VIL VIH VOL VOH IIL IILSTR VOLOD AUI Ports IIAXD VAICM VAIDV VASQ VATH VAOD VAOC VAODI VAODOFF IAODOFF VAOCM IIRXD RRXD VTIVB VTID Input Current at DI± and CI± Pairs DI±, CI± Open Circuit Input Voltage Range Differential Mode Input Voltage Range (DI, CI) DI, CI Squelch Threshold DI Switching Threshold Differential Output Voltage (DO+) – (DO) Differential Output Voltage (CI+) – (CI–) (Reverse Mode) DO Differential Output Voltage Imbalance DO Differential Idle Output Voltage DO Differential Idle Output Current DO+, DO- Common Mode Output Voltage Input Current at RXD± and CI± Pairs RXD Differential Input RXD+, RXD– Open Circuit Input Voltage (bias) Differential Mode Input Range (RXD) VDD = 5.0 V VSS