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AR# 13291

4.1i Virtex-II PAR - Router not finding low skew paths for LVPECL_33 output.


Keywords: LVPECL, LVPECL_33, skew, output, path, DIFFO, OBUFDS

Urgency: Hot

General Description:
My router is not making low skew connections to the DIFFM and DIFFS IOBs used in an LVPECL_33 output path, even though a MAXSKEW timing constraint is being applied to the signal involved.

(Investigation of this issue revealed that timing analysis of the LVPECL DIFFS paths had been incorrectly turned off in the timing analysis software.)


This problem will be fixed in 4.2i, which will become available in February, 2002.

Meanwhile, a patch is available that is compatible with all 4.1i versions and all hardware platforms:


To install the patch, unzip it in the XILINX install directory while maintaining the directory structure:

gzip -d 4.1i_par_sol_13291.tar.gz
tar xvf 4.1i_par_sol_13291.tar

A MAXSKEW constraint must be applied to the input net to the OBUFDS for this patch to have any affect.

NOTE: Please ignore the 3.1i reference in the path above - - this is a 4.1i only patch.
AR# 13291
Date Created 08/29/2007
Last Updated 10/20/2008
Status Archive
Type General Article