AR# 19627

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Spartan-3/-3E/-3A - Does Spartan-3/-3E/-3A have true differential termination (DT) in its IOBs?

Description

Keywords: LVDS_25_DT, LDT_25_DT

Does Spartan-3/-3E/-3A have true differential termination (DT) in its IOBs?

Solution

* Spartan-3 does not have differential termination in its IOBs.

* Spartan-3E does have true differential termination in its IOBs which can be used in a 2.5V bank with LVDS, BLVDS and mini-LVDS receivers. Note that DT is not available for the Spartan-3E dedicated input pins.

For more information on the Spartan-3E differential termination (DT), see the Spartan-3E Functional Description Data Sheet located at:
http://direct.xilinx.com/bvdocs/userguides/ug331.pdf

* Spartan-3A does have true differential termination on its IOBs which can be used in both a 2.5V and a 3.3V bank. Note that DT is not available for the Spartan-3A dedicated input pins.

Please see the Spartan-3A Data Sheet for more information on the exact value of the differential termination resistance (Rdt) at the different Vcco levels:
http://direct.xilinx.com/bvdocs/publications/ds529.pdf


NOTE:
To enable the differential termination for a differential I/O pair, set the DIFF_TERM attribute to TRUE.

The DIFF_TERM attribute uses the following syntax in the UCF file:
INST <I/O_BUFFER_INSTANTIATION_NAME> DIFF_TERM = <TRUE/FALSE>;

For more information on differential termination usage, please see the Spartan-3 Generation +54 ` User Guide at:
http://direct.xilinx.com/bvdocs/userguides/ug331.pdf


AR# 19627
Date 12/18/2006
Status Active
Type General Article
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