TLK1501

0.6 TO 1.5 GBPS TRANSCEIVER

SLLS428F − JUNE 2000 − REVISED JANUARY 2004

21

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

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

TLK1501 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, 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.