TLK2501

1.5 TO 2.5 GBPS TRANSCEIVER

SLLS427D − AUGUST 2000 − REVISED JULY 2003

20

POST OFFICE BOX 655303

APPLICATION INFORMATION

recommended values of external resistors (1% tolerance)

PARAMETER

TEST CONDITIONS

RECOMMENDED

UNIT

R(t), Termination resistor

50

Ω environment

50

Ω

R(t), Termination resistor

75

Ω environment

75

Ω

R(REF), Reference resistor

50

Ω environment

200

Ω

R(REF), Reference resistor

75

Ω environment

300

Ω

RREF − Resistor Reference −

Ω

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

100

150

200

250

300

VOLTAGE

vs

RESISTOR REFERENCE

VODP at 75

Ω

VODD at 50

Ω

VODD at 75

Ω

VODP at 50

Ω

Figure 14. Differential Transmitter Voltage

choosing RREF resistor values

TLK2501 offers the flexibility to customize the voltage swing and transmission line termination by adjusting the

be optimized for a particular transmission line impedance, length, and controlling the output swing for EMI and

attenuation concerns. Refer to Figure 14 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 15 for high-speed

I/O directly coupled mode and Figure 16 for high-speed I/O ac-coupled mode.