DS90CR217
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SNLS226A – OCTOBER 2006 – REVISED FEBRUARY 2013
DS90CR217 +3.3V Rising Edge Data Strobe LVDS 21-Bit Channel Link - 85 MHz
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FEATURES
DESCRIPTION
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The DS90CR217 transmitter converts 21 bits of
CMOS/TTL data into three LVDS (Low Voltage
Differential Signaling) data streams. A phase-locked
transmit clock is transmitted in parallel with the data
streams over a fourth LVDS link. Every cycle of the
transmit clock 21 bits of input data are sampled and
transmitted. At a transmit clock frequency of 85 MHz,
21 bits of TTL data are transmitted at a rate of 595
Mbps per LVDS data channel. Using a 85 MHz clock,
the data throughput is 1.785 Gbit/s (223 Mbytes/sec).
1
2
20 to 85 MHz Shift Clock Support
50% Duty Cycle on Receiver Output Clock
Best-in-Class Set & Hold Times on TxINPUTs
Low Power Consumption
±1V Common-Mode Range (Around +1.2V)
Narrow Bus Reduces Cable Size and Cost
Up to 1.785 Gbps Throughput
Up to 223 Mbytes/sec Bandwidth
345 mV (typ) Swing LVDS Devices for Low EMI
PLL Requires No External Components
Rising Edge Data Strobe
Compatible with TIA/EIA-644 LVDS Standard
Low Profile 48-Lead TSSOP Package
The narrow bus and LVDS signalling of the
DS90CR217 is an ideal means to solve EMI and
cable size problems associated with wide, high-speed
TTL interfaces.
Block Diagram
Figure 1. DS90CR217
See Package Number DGG0048A
1
2
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2006–2013, Texas Instruments Incorporated
DS90CR217
SNLS226A – OCTOBER 2006 – REVISED FEBRUARY 2013
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Connection Diagrams
Figure 2.
Typical Application
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
2
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Absolute Maximum Ratings
(1) (2) (1)
−0.3V to +4V
Supply Voltage (VCC)
CMOS/TTL Input Voltage
−0.5V to (VCC + 0.3V)
CMOS/TTL Output Voltage
−0.3V to (VCC + 0.3V)
LVDS Receiver Input Voltage
−0.3V to (VCC + 0.3V)
LVDS Driver Output Voltage
−0.3V to (VCC + 0.3V)
LVDS Output Short
Circuit Duration
Continuous
Junction Temperature
+150°C
−65°C to +150°C
Storage Temperature Range
Lead Temperature
(Soldering, 4 sec.)
+260°C
Maximum Package Power Dissipation @ +25°C
DGG0048A (TSSOP) Package:
DS90CR217
1.98 W
Package Derating
DS90CR217
16 mW/°C above +25°C
ESD Rating
(HBM, 1.5kΩ, 100pF)
> 7kV
(EIAJ, 0Ω, 200pF)
> 700V
Latch Up Tolerance @ 25°C
(1)
> ±300mA
If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and
specifications.
“Absolute Maximum Ratings” are those values beyond which the safety of the device cannot be guaranteed. They are not meant to
imply that the device should be operated at these limits. “Electrical Characteristics” specify conditions for device operation.
(2)
Recommended Operating Conditions
Min
Nom
Max
Units
3.0
3.3
3.6
V
Temperature (TA)
−10
+25
+70
°C
Receiver Input Range
0
2.4
V
Supply Voltage (VCC)
Operating Free Air
Supply Noise Voltage (VCC)
100
mVPP
Electrical Characteristics
Over recommended operating supply and temperature ranges unless otherwise specified
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
s
CMOS/TTL DC SPECIFICATIONS
VIH
High Level Input Voltage
2.0
VCC
V
VIL
Low Level Input Voltage
GND
0.8
V
VCL
Input Clamp Voltage
ICL = −18 mA
−0.7
9
−1.5
V
IIN
Input Current
VIN = 0.4V, 2.5V or VCC
+1.8
+15
μA
IOS
Output Short Circuit Current
−60
−120
mA
290
450
mV
35
mV
VIN = GND
−10
VOUT = 0V
μA
0
LVDS DRIVER DC SPECIFICATIONS
VOD
Differential Output Voltage
ΔVOD
Change in VOD between Complimentary Output
States
RL = 100Ω
250
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Electrical Characteristics (continued)
Over recommended operating supply and temperature ranges unless otherwise specified
Symbol
Parameter
Conditions
(1)
Min
Typ
Max
Unit
s
1.12
5
1.25
1.37
5
V
35
mV
VOS
Offset Voltage
ΔVOS
Change in VOS between Complimentary Output
States
IOS
Output Short Circuit Current
VOUT = 0V, RL = 100Ω
−3.5
−5
mA
IOZ
Output TRI-STATE Current
PWR DWN = 0V, VOUT = 0V or VCC
±1
±10
μA
RL = 100Ω,
CL = 5 pF,
Worst Case Pattern
(Figure 3 and Figure 4)
f = 33 MHz
28
42
mA
f = 40 MHz
29
47
mA
f = 66 MHz
34
52
mA
f = 85 MHz
39
57
mA
10
55
μA
TRANSMITTER SUPPLY CURRENT
ICCTW
Transmitter Supply Current Worst Case (with
Loads)
ICCTZ
(1)
Transmitter Supply Current Power Down
PWR DWN = Low
Driver Outputs in TRI-STATE
under Powerdown Mode
VOS previously referred as VCM.
Transmitter Switching Characteristics
Over recommended operating supply and temperature ranges unless otherwise specified
Symbol
Parameter
Min
Typ
Max
Units
LLHT
LVDS Low-to-High Transition Time (Figure 4)
0.75
1.5
ns
LHLT
LVDS High-to-Low Transition Time (Figure 4)
0.75
1.5
ns
TCIT
TxCLK IN Transition Time (Figure 5)
6.0
ns
TPPos0
Transmitter Output Pulse Position for Bit0 (Figure 12)
−0.20
0
0.20
ns
TPPos1
Transmitter Output Pulse Position for Bit1
1.48
1.68
1.88
ns
TPPos2
Transmitter Output Pulse Position for Bit2
3.16
3.36
3.56
ns
TPPos3
Transmitter Output Pulse Position for Bit3
4.84
5.04
5.24
ns
TPPos4
Transmitter Output Pulse Position for Bit4
6.52
6.72
6.92
ns
TPPos5
Transmitter Output Pulse Position for Bit5
8.20
8.40
8.60
ns
TPPos6
Transmitter Output Pulse Position for Bit6
9.88
10.08
10.28
ns
TCIP
TxCLK IN Period (Figure 7)
11.76
T
50
ns
TCIH
TxCLK IN High Time (Figure 7)
0.35T
0.5T
0.65T
ns
TCIL
TxCLK IN Low Time (Figure 7)
0.35T
0.5T
0.65T
ns
TSTC
TxIN Setup to TxCLK IN (Figure 7)
THTC
TxIN Hold to TxCLK IN (Figure 7)
TCCD
TxCLK IN to TxCLK OUT Delay @ 25°C, VCC = 3.3V (Figure 8)
TPLLS
1.0
f = 85 MHz
f = 85 MHz
2.5
ns
0
ns
6.3
ns
Transmitter Phase Lock Loop Set (Figure 9)
10
ms
TPDD
Transmitter Powerdown Delay (Figure 11)
100
ns
TJIT
TxCLK IN Cycle-to-Cycle Jitter
2
ns
4
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3.8
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AC Timing Diagrams
Figure 3. “Worst Case” Test Pattern
Figure 4. DS90CR217 (Transmitter) LVDS Output Load and Transition Times
Figure 5. D590CR217 (Transmitter) Input Clock Transition Time
Measurements at VDIFF = 0V
TCCS measured between earliest and latest LVDS edges
TxCLK Differential Low→High Edge
Figure 6. DS90CR217 (Transmitter) Channel-to-Channel Skew
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Figure 7. DS90CR217 (Transmitter) Setup/Hold and High/Low Times
Figure 8. DS90CR217 (Transmitter) Clock In to Clock Out Delay
Figure 9. DS90CR217 (Transmitter) Phase Lock Loop Set Time
Figure 10. 21 Parallel TTL Data Inputs Mapped to LVDS Outputs (DS90CR217)
6
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Figure 11. Transmitter Powerdown Delay
Figure 12. Transmitter LVDS Output Pulse Position Measurement
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APPLICATIONS INFORMATION
Table 1. DS90CR217 PIN DESCRIPTIONS — CHANNEL LINK TRANSMITTER
I/O
No.
TxIN
Pin Name
I
21
TTL level input.
Description
TxOUT+
O
3
Positive LVDS differential data output.
TxOUT−
O
3
Negative LVDS differential data output.
TxCLK IN
I
1
TTL level clock input. The rising edge acts as data strobe. Pin name TxCLK IN.
TxCLK OUT+
O
1
Positive LVDS differential clock output.
TxCLK OUT−
O
1
Negative LVDS differential clock output.
PWR DWN
I
1
TTL level input. Assertion (low input) TRI-STATEs the outputs, ensuring low current at power down. See
Applications Information section.
VCC
I
4
Power supply pins for TTL inputs.
GND
I
5
Ground pins for TTL inputs.
PLL VCC
I
1
Power supply pins for PLL.
PLL GND
I
2
Ground pins for PLL.
LVDS VCC
I
1
Power supply pin for LVDS outputs.
LVDS GND
I
3
Ground pins for LVDS outputs.
The Channel Link devices are intended to be used in a wide variety of data transmission applications. Depending
upon the application the interconnecting media may vary. For example, for lower data rate (clock rate) and
shorter cable lengths (< 2m), the media electrical performance is less critical. For higher speed/long distance
applications the media's performance becomes more critical. Certain cable constructions provide tighter skew
(matched electrical length between the conductors and pairs). Twin-coax for example, has been demonstrated at
distances as great as 5 meters and with the maximum data transfer of 1.785 Gbit/s. Additional applications
information can be found in the following Interface Application Notes:
AN = ####
Topic
AN-1041 (SNLA218)
Introduction to Channel Link
AN-1108 (SNLA008)
Channel Link PCB and Interconnect Design-In Guidelines
AN-1109 (SNLA220)
Multi-Drop Channel-Link Operation
AN-806 (SNLA026)
Transmission Line Theory
AN-905 (SNLA035)
Transmission Line Calculations and Differential Impedance
AN-916 (SNLA219)
Cable Information
CABLES
A cable interface between the transmitter and receiver needs to support the differential LVDS pairs. The ideal
cable/connector interface would have a constant 100Ω differential impedance throughout the path. It is also
recommended that cable skew remain below 90ps (@ 85 MHz clock rate) to maintain a sufficient data sampling
window at the receiver.
In addition to the four or five cable pairs that carry data and clock, it is recommended to provide at least one
additional conductor (or pair) which connects ground between the transmitter and receiver. This low impedance
ground provides a common-mode return path for the two devices. Some of the more commonly used cable types
for point-to-point applications include flat ribbon, flex, twisted pair and Twin-Coax. All are available in a variety of
configurations and options. Flat ribbon cable, flex and twisted pair generally perform well in short point-to-point
applications while Twin-Coax is good for short and long applications. When using ribbon cable, it is
recommended to place a ground line between each differential pair to act as a barrier to noise coupling between
adjacent pairs. For Twin-Coax cable applications, it is recommended to utilize a shield on each cable pair. All
extended point-to-point applications should also employ an overall shield surrounding all cable pairs regardless
of the cable type. This overall shield results in improved transmission parameters such as faster attainable
speeds, longer distances between transmitter and receiver and reduced problems associated with EMS or EMI.
8
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The high-speed transport of LVDS signals has been demonstrated on several types of cables with excellent
results. However, the best overall performance has been seen when using Twin-Coax cable. Twin-Coax has very
low cable skew and EMI due to its construction and double shielding. All of the design considerations discussed
here and listed in the supplemental application notes provide the subsystem communications designer with many
useful guidelines. It is recommended that the designer assess the tradeoffs of each application thoroughly to
arrive at a reliable and economical cable solution.
BOARD LAYOUT
To obtain the maximum benefit from the noise and EMI reductions of LVDS, attention should be paid to the
layout of differential lines. Lines of a differential pair should always be adjacent to eliminate noise interference
from other signals and take full advantage of the noise canceling of the differential signals. The board designer
should also try to maintain equal length on signal traces for a given differential pair. As with any high-speed
design, the impedance discontinuities should be limited (reduce the numbers of vias and no 90 degree angles on
traces). Any discontinuities which do occur on one signal line should be mirrored in the other line of the
differential pair. Care should be taken to ensure that the differential trace impedance match the differential
impedance of the selected physical media (this impedance should also match the value of the termination
resistor that is connected across the differential pair at the receiver's input). Finally, the location of the CHANNEL
LINK TxOUT pins should be as close as possible to the board edge so as to eliminate excessive pcb runs. All of
these considerations will limit reflections and crosstalk which adversely effect high frequency performance and
EMI.
UNUSED INPUTS
All unused inputs at the TxIN inputs of the transmitter may be tied to ground or left no connect.
TERMINATION
Use of current mode drivers requires a terminating resistor across the receiver inputs. The CHANNEL LINK
chipset will normally require a single 100Ω resistor between the true and complement lines on each differential
pair of the receiver input. The actual value of the termination resistor should be selected to match the differential
mode characteristic impedance (90Ω to 120Ω typical) of the cable. Figure 13 shows an example. No additional
pull-up or pull-down resistors are necessary as with some other differential technologies such as PECL. Surface
mount resistors are recommended to avoid the additional inductance that accompanies leaded resistors. These
resistors should be placed as close as possible to the receiver input pins to reduce stubs and effectively
terminate the differential lines.
Figure 13. LVDS Serialized Link Termination
DECOUPLING CAPACITORS
Bypassing capacitors are needed to reduce the impact of switching noise which could limit performance. For a
conservative approach three parallel-connected decoupling capacitors (Multi-Layered Ceramic type in surface
mount form factor) between each VCC and the ground plane(s) are recommended. The three capacitor values are
0.1 μF, 0.01 μF and 0.001 μF. An example is shown in Figure 14. The designer should employ wide traces for
power and ground and ensure each capacitor has its own via to the ground plane. If board space is limiting the
number of bypass capacitors, the PLL VCC should receive the most filtering/bypassing. Next would be the LVDS
VCC pins and finally the logic VCC pins.
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Figure 14. CHANNEL LINK
Decoupling Configuration
CLOCK JITTER
The CHANNEL LINK devices employ a PLL to generate and recover the clock transmitted across the LVDS
interface. The width of each bit in the serialized LVDS data stream is one-seventh the clock period. For example,
a 85 MHz clock has a period of 11.76 ns which results in a data bit width of 1.68 ns. Differential skew (Δt within
one differential pair), interconnect skew (Δt of one differential pair to another) and clock jitter will all reduce the
available window for sampling the LVDS serial data streams. Care must be taken to ensure that the clock input
to the transmitter be a clean low noise signal. Individual bypassing of each VCC to ground will minimize the noise
passed on to the PLL, thus creating a low jitter LVDS clock. These measures provide more margin for channelto-channel skew and interconnect skew as a part of the overall jitter/skew budget.
COMMON-MODE vs. DIFFERENTIAL MODE NOISE MARGIN
The typical signal swing for LVDS is 300 mV centered at +1.2V. The CHANNEL LINK receiver supports a 100
mV threshold therefore providing approximately 200 mV of differential noise margin. Common-mode protection is
of more importance to the system's operation due to the differential data transmission. LVDS supports an input
voltage range of Ground to +2.4V. This allows for a ±1.0V shifting of the center point due to ground potential
differences and common-mode noise.
TRANSMITTER INPUT CLOCK
The transmitter input clock must always be present when the device is enabled (PWR DWN = HIGH). If the clock
is stopped, the PWR DWN pin must be used to disable the PLL. The PWR DWN pin must be held low until after
the input clock signal has been reapplied. This will ensure a proper device reset and PLL lock to occur.
POWER SEQUENCING AND POWERDOWN MODE
Outputs of the CHANNEL LINK transmitter remain in TRI-STATE until the power supply reaches 2V. Clock and
data outputs will begin to toggle 10 ms after VCC has reached 3V and the Powerdown pin is above 1.5V. Either
device may be placed into a powerdown mode at any time by asserting the Powerdown pin (active low). Total
power dissipation for each device will decrease to 5 μW (typical).
The transmitter input clock may be applied prior to powering up and enabling the transmitter. The transmitter
input clock may also be applied after power up; however, the use of the PWR DWN pin is required as described
in the TRANSMITTER INPUT CLOCK section. Do not power up and enable (PWR DWN = HIGH) the transmitter
without a valid clock signal applied to the TxCLK IN pin.
The CHANNEL LINK chipset is designed to protect itself from accidental loss of power to either the transmitter or
receiver. If power to the transmit board is lost, the receiver clocks (input and output) stop. The data outputs
(RxOUT) retain the states they were in when the clocks stopped. When the receiver board loses power, the
receiver inputs are shorted to VCC through an internal diode. Current is limited (5 mA per input) by the fixed
current mode drivers, thus avoiding the potential for latchup when powering the device.
10
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Figure 15. Single-Ended and Differential Waveforms
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REVISION HISTORY
Changes from Original (February 2013) to Revision A
•
12
Page
Changed layout of National Data Sheet to TI format .......................................................................................................... 11
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PACKAGE OPTION ADDENDUM
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10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
(3)
Device Marking
(4/5)
(6)
DS90CR217MTD/NOPB
ACTIVE
TSSOP
DGG
48
38
RoHS & Green
SN
Level-2-260C-1 YEAR
-10 to 70
DS90CR217MTD
>B
DS90CR217MTDX/NOPB
ACTIVE
TSSOP
DGG
48
1000
RoHS & Green
SN
Level-2-260C-1 YEAR
-10 to 70
DS90CR217MTD
>B
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of