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AR# 33113

Timing Analyzer - Different "clock to pad" values between analyses using autogenerated timing constraints VS user specified endpoints


When doing timing analysis using auto generated timing constraints (trce -a option), the clock to out value is different from when doing timing analysis by user specified endpoints (FF to pad). 

Why does this happen?


This is an expected behavior. 

This is because when running analysis using user specified endpoints, clock uncertainty is not included in the calculation as the period constraints are not involved.

The difference in the clock to out values comes from the clock uncertainty.

AR# 33113
Date Created 08/06/2009
Last Updated 09/03/2014
Status Active
Type General Article
  • ISE Design Suite