GS7025 PRO-LINX™ Serial Digital Receiver

Data Sheet

13813 - 7

October 2009

19 of 23

Figure 3-9: Digital Inputs - single-ended input interface

When the DDI and the DDI inputs are not used, saturate one input of the differential

amplifier for improved noise immunity. To saturate, connect either pins 44 and 1 or pins

2 and 3 to VCC. Leave the other pair floating.

3.3.2 High Speed Outputs (SDO/SDO and SCO/SCO)

SDO/SDO and SCO/SCO are current mode outputs that require external pullup resistors

(see Figure 3-10). To calculate the output sink current, use the following relationship:

Output Sink Current = Output Signal Swing / Pullup Resistor

A diode can be placed between Vcc and the pullup resistors to reduce the common

mode voltage by approximately 0.7V. When the output traces are longer than 1in,

controlled impedance traces should be used. The pullup resistors should be placed at the

end of the output traces as they terminate the trace in its characteristic impedance

(75Ω).

Figure 3-10: High-speed Outputs with External Pullups

DDI

DDI

GS7025

SDO

SDO

SCO

SCO

75

75

75

75

GS7025