set_clock_uncertainty Constraint

set_clock_uncertainty [-setup] [-hold] [-from <clock>] [-rise_from <clock>] \
    [-fall_from <clock>] [-to <clock>] [-rise_to <clock>] [-fall_to <clock>] \
    <uncertainty>

This constraint specifies the uncertainty for clocks or clock-to-clocks transfers. The tool added the specified uncertainty value to the derived uncertainty. If you do not specify source or destination clocks, the tool applies the uncertainty to all clocks in the design. If you do not specify a setup or hold, the tool uses the uncertainty value for both setup and hold.

  • -setup is the clock uncertainty for setup analysis
  • -hold is the clock uncertainty for hold analysis
  • -from source clock
  • -rise_from source clock with rising edge
  • -fall_from source clock with falling edge
  • -to destination clock
  • -rise_to destination clock with rising edge
  • -fall_to destination clock with falling edge
  • <uncertainty> is the clock uncertainty value

See How to Set Clock Uncertainty.