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GPI input problem UCD90124A

JacobV1587
Intellectual 260 points

Other Parts Discussed in Thread: UCD90124A

I use a UCD90124A sequencer with firmware 2.4.0.

I make a RESETn output from several POWER_GOOD outputs and one GPI (pin 18).
Sometimes the RESETn output goes unwanted low and goes mostly never high. Sometimes the RESETn line goes high after +/- 25 ms. But there are no POWER or GPI fault logged.

When I remove the GPI dependence, the RESETn line works fine. I make the conclusion the problem is the GPI input.
I monitor the input with a oscilloscope but no glitch are found. I saw only a voltage dip of 100 mV. I place a small capacitor on the GPI input and I don't see the voltage dip but the problem still exist. I measure also the sequencer power but no voltage dips are found.

This problem occurs only when an open-drain output (pin 11)  is pulled low by an external device.

Next I make an other GPI dependence (only pin 20) and the problem doesn't  appear!

Any idea?

  • 0
    TI__Intellectual 1595 points

    Hi Jacob,

    I apologize for not responding to your post. This post somehow skipped from my inbox . Can you please share with me the schematic. I have your project file unless it's modified later. Is the pin 11 routed to any other pin on the board? Also can you check the rail behaviors or share some scope shots of the rail1, rail3, pin18 when you see the RESET going unwanted low. You can email me directly at s-kocherlakota@ti.com to give your response or for any further questions on the UCD90XX.

    Thanks, Spandana