ICS8543 Data Sheet LOW SKEW, 1-to-4, DIFFERENTIAL-TO-LVDS FANOUT BUFFER
ICS8543BG REVISION E DECEMBER 17, 2010 13 ©2010 Integrated Device Technology, Inc.
Recommendations for Unused Input and Output Pins
Inputs:
CLK/nCLK INPUTS
For applications not requiring the use of the differential input, both
CLK and nCLK can be left floating. Though not required, but for
additional protection, a 1kΩ resistor can be tied from CLK to ground.
PCLK/nPCLK INPUTS
For applications not requiring the use of the differential input, both
PCLK and nPCLK can be left floating. Though not required, but for
additional protection, a 1kΩ resistor can be tied from PCLK to
ground.
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 1kΩ resistor can be used.
Outputs:
LVDS Outputs
All unused LVDS outputs should be terminated with 100Ω resistor
between the differential pair.
LVDS Driver Termination
A general LVDS interface is shown in Figure 5. Standard termination
for LVDS type output structure requires both a 100Ω parallel resistor
at the receiver and a 100Ω differential transmission line environment.
In order to avoid any transmission line reflection issues, the 100Ω
resistor must be placed as close to the receiver as possible. IDT
offers a full line of LVDS compliant devices with two types of output
structures: current source and voltage source. The standard
termination schematic as shown in Figure 5 can be used with either
type of output structure. If using a non-standard termination, it is
recommended to contact IDT and confirm if the output is a current
source or a voltage source type structure. In addition, since these
outputs are LVDS compatible, the amplitude and common mode
input range of the input receivers should be verified for compatibility
with the output.
Figure 5. Typical LVDS Driver Termination
100Ω
–
+
100Ω Differential Transmission Line
LVDS Driver
LVDS
Receiver
