
ICS8741004
DIFFERENTIAL-TO-LVDS/0.7V DIFFERENTIAL PCI EXPRESS JITTER ATTENUATOR
IDT / ICS PCI EXPRESS JITTER ATTENUATOR
12
ICS8741004AG REV. AMAY 29, 2008
Recommendations for Unused Input and Output Pins
Inputs:
LVCMOS Control Pins
All control pins have internal pull-ups or pull-downs; additional
resistance is not required but can be added for additional
protection. A 1k
resistor can be used.
Outputs:
Differential Outputs
All unused differential outputs can be left floating. We recommend
that there is no trace attached. Both sides of the differential output
pair should either be left floating or terminated.
LVDS Outputs
All unused LVDS output pairs can be either left floating or
terminated with 100
across. If they are left floating, we
recommend that there is no trace attached.
LVDS Driver Termination
A general LVDS interface is shown in Figure 4. In a 100
differential transmission line environment, LVDS drivers require a
matched load termination of 100
across near the receiver input.
For a multiple LVDS outputs buffer, if only partial outputs are used,
it is recommended to terminate the unused outputs.
Figure 4. Typical LVDS Driver Termination
3.3V
LVDS Driver
R1
100
–
+
3.3V
50
50
100
Differential Transmission Line