TLK2701 Datasheet, PDF (16/21 Pages) Texas Instruments – 1.6 TO 2.7 GBPS TRANSCEIVER

TLK2701
1.6 TO 2.7 GBPS TRANSCEIVER
SLLS429B – AUGUST 2000 – REVISED MAY 2002
APPLICATION INFORMATION
recommended values of external resistors (1% tolerance)
R(t), Termination resistor
PARAMETER
R(REF), Reference resistor
TEST CONDITIONS
50 Ω environment
75 Ω environment
50 Ω environment
75 Ω environment
RECOMMENDED
50
75
200
300
UNIT
Ω
Ω
VOLTAGE
vs
RESISTOR REFERENCE
2.00
1.80
VODD at 75 Ω
1.60
VODP at 75 Ω
1.40
1.20
1.00 ^{VODD at 50 Ω}
0.80
VODP at 50 Ω
0.60
100.00
150.00
200.00
250.00
RREF – Resistor Reference – Ω
300.00
Figure 10. Differential Transmitter Voltage
choosing resistor values
TLK2701 offers the flexibility to customize the voltage swing and transmission line termination by adjusting the
reference resistor, RREF, and termination resistor, R_t. By choosing particular resistor values, the system can
be optimized for a particular transmission line impedance, length, and controlling the output swing for EMI and
attenuation concerns. Refer to Figure 10 to determine the nominal voltage swing and driver current as a function
of resistor values. It is recommended that 1% tolerance resistors be used. Refer to Figure 11 for high-speed
I/O directly coupled mode and Figure 12 for high-speed I/O ac-coupled mode.
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