Signal connections on UCD9081 8-ch Power sequencer:
For simplicity, I am presenting only 4 signals where there is a problem.
There are four power good signals on input monitoring pins and 4 output enable signals.
They are connected on UCD9081 in this order:
Inputs - rail # - Outputs - parent rail
==============================
MON4 - rail 4 - EN4 (parent rail is 4)
MON5 - rail 5 - EN5 (parent rail is 5)
MON6 - rail 6 - EN6 (parent rail is 6)
MON7 - rail 7 - EN7 (parent rail is 7)
MON4, 5, 6, and 7 are power good signals coming from 4 power rails.
EN# signals are delayed 10ms after the MON# signals.
Setup:
1) UCD9081 EVM GUI is set: Advanced Mode, Allow Self-dependencies.
2) Alarm Processing: Sequence
3) Parent rails setup:
Output EN# is referenced to the same input rail MON#.
EN4 (parent rail is 4)
EN5 (parent rail is 5)
EN6 (parent rail is 6)
EN7 (parent rail is 7)
Problem:
When the fault is simulated on any of MON4, 5, 6, or 7 inputs, the power sequencer doesn't sequence output signals EN4, 5, 6, and 7.
Note:
If Advanced Mode with Self Dependences is NOT used, then EN 4, 5, 6, and 7 are sequenced when a fault is present on MON 4, 5, 6, or 7 inputs.
But the problem, in this case, is that dependencies are now different and not desirable, and timing gets different:
Now dependencies are like this:
EN4 (parent rail is 3)
EN5 (parent rail is 4)
EN6 (parent rail is 5)
EN7 (parent rail is 6)
Why power sequencer in this application is not sequencing EN4, 5, 6, and 7 signals (toggling OFF-ON) after a fault is present on input MON signals when Advanced mode is used with Allowed Self-dependencies?
Thank you,