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AR# 64188

MIG UltraScale - sys_rst missing set_false_path constraint


Version Found: MIG UltraScale v7.0
Version Resolved: See (Xilinx Answer 58435)

(PG150) states that the sys_rst is an asynchronous input that must be asserted for a minimum of 20 cycles of the controller clock.

Please disregard the 20 clock cycle requirement.

The sys_rst input port is an asynchronous reset which goes through synchronization logic so the 20 cycle requirement is not required and will be removed from (PG150) in a future release. 

The asynchronous sys_rst port drives the PRE input pins to the MIG IP core synchronization logic but there are no set_false_path timing constraints on this path.

In some designs, this can make timing closure difficult so a set_false_path constraint should be applied to the sys_rst.


To ignore the timing paths for the asynchronous sys_rst to the synchronization logic, the following example constraint can be applied:

set_false_path -to [get_pins -hierarchical -filter {NAME =~ *infrastructure/rst*_sync_r*/PRE}]

Revision History:
04/08/2015 - Initial Release

Linked Answer Records

Master Answer Records

Answer Number Answer Title Version Found Version Resolved
58435 DDR4, DDR3, QDRIV, QDRII+, RLDRAM3, LPDDR3 UltraScale and UltraScale+ - IP Release Notes and Known Issues N/A N/A
AR# 64188
Date 04/16/2015
Status Active
Type Known Issues
  • Kintex UltraScale
  • Virtex UltraScale
  • MIG UltraScale
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