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AR# 37317

MAP - WARNING:Timing - Feedback on Clock Modifying COMP pll_base_i/PLL_ADV forms an incomplete loop.

Description


For GTP designs using PLLs with feedback pins going through the GTP, the following warning message is reported:
 

WARNING:Timing - Feedback on Clock Modifying COMP pll_base_i/PLL_ADV forms an incomplete loop. The Tdcmino calculation will be invalid. If
the Clock Modifying COMP uses external feedback, please apply the FEEDBACK constraint to indicate the external board delay. Consult the
Constraints Guide for further information on how to apply the FEEDBACK constraint.


Solution


This warning message can be ignored.

The feedback path through the GTP is valid.


Revision History:
09/08/2010 - Initial Release
AR# 37317
Date Created 08/09/2010
Last Updated 02/18/2015
Status Active
Type General Article
Devices
  • Spartan-6 LXT
Tools
  • ISE Design Suite