UPGRADE YOUR BROWSER

We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

AR# 13119

8.1i Virtex-II MAP - Why are my OBUFDS components not using the DIFFO signals for LVPECL?

Description

When I design with an OBUFDS and use LVPECL, the tools do not utilize the DIFFO_OUT in the DIFFM and the DIFFO_IN in the DIFFS. Why?

Solution

The DIFFO_IN connection, which is used for LVDS outputs, is not supported in the hardware for LVPECL_33 outputs. For LVPECL_33 outputs, normal output paths are used to drive both DIFFM and DIFFS paths. A MAXSKEW constraint should be used to minimize skew between the DIFFM and DIFFS paths.

AR# 13119
Date Created 08/29/2007
Last Updated 12/15/2012
Status Active
Type General Article