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AR# 60388

MMCM/PLL LOCKED goes high even when VCO is out of spec

Description

Even when the Fvco is out of spec we see that the MMCM/PLL LOCKED output is high.

Solution

It is possible that very low VCO frequencies where the VCO frequency is out of spec, can achieve LOCKED = 1.

However, if the VCO frequency is out of spec we cannot guarantee that the MMCM/PLL will achieve LOCKED "always" because we do not characterize at those out of spec VCO frequencies.

The user should always check that the MMCM/PLL is operating within the VCO frequency and then check for LOCKED = 1.
AR# 60388
Date Created 04/23/2014
Last Updated 06/30/2014
Status Active
Type Known Issues
Devices
  • Virtex-7
  • Artix-7
  • Kintex-7