ICS8543BGI REVISION E NOVEMBER 15, 2012

12

©2012 Integrated Device Technology, Inc.

ICS8543I Data Sheet

LOW SKEW, 1-to-4, DIFFERENTIAL-TO-LVDS FANOUT BUFFER

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 1k

 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 1k

 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 1k

 resistor can be used.

Outputs:

LVDS Outputs

All unused LVDS output pairs can be either left floating or terminated

with 100

 across. If they are left floating, there should be no trace

attached.

LVDS Driver Termination

For a general LVDS interface, the recommended value for the

your transmission line. A typical point-to-point LVDS design uses a

100

 parallel resistor at the receiver and a 100 differential

transmission-line environment. In order to avoid any

transmission-line reflection issues, the components should be

surface mounted and 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 5A can be used

with either type of output structure. Figure 5B, which can also be

used with both output types, is an optional termination with center tap

capacitance to help filter common mode noise. The capacitor value

should be approximately 50pF. If using a non-standard termination, it

is recommended to contact IDT and confirm if the output structure is

current source or voltage source type. In addition, since these

outputs are LVDS compatible, the input receiver’s amplitude and

common-mode input range should be verified for compatibility with

the output.

LVDS Termination

LVDS

Driver

LVDS

Driver

LVDS

Receiver

LVDS

Receiver

C

2

2

Figure 5A. Standard Termination

Figure 5B. Optional Termination