TLK4015 Datasheet, PDF (20/24 Pages) Texas Instruments – QUAD 0.6 TO 1.5 Gbps TRANSCEIVER

TLK4015
QUAD 0.6 to 1.5 Gbps TRANSCEIVER
SLLS541 – DECEMBER 2002
recommended values of external resistors (1% tolerance)
PARAMETER
Rt
Termination resistor
RREF Reference resistor
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
2.0
1.8
VODD at 75 Ω
1.6
VODP at 75 Ω
1.4
1.2
VODD at 50 Ω
1.0
0.8
VODP at 50 Ω
0.6
100
150
200
250
300
RREF – Resistor Reference – Ω
Figure 13. Differential Transmitter Voltage
choosing resistor values
TLK4015 offers the flexibility to customize the voltage swing and transmission line termination by adjusting the
reference resistor, RREF, and termination resistor, Rt. By choosing particular resistor values, the system can
be optimized for a particular transmission line impedance and length as well as for controlling the output swing
for EMI and attenuation concerns. Refer to Figure 13 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 14 for
the high-speed-I/O directly coupled mode and to Figure 15 for the high-speed-I/O ac-coupled mode.
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