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UCD9090: Pin select rail states function

Brian Wang0
Expert 5310 points
Part Number: UCD9090

Hi Champs,

Here is some questions about UCD9090:

1. In UCD9090 GUI can we use pin select rail states config to connect 3 PowerGood signal to GPI1/2/3 and control all rails with the sequence on/off dependencies?

We noted below description seems we could achieve this function:

But in the GUI seems the power on follows the sequence but power off is immediately. And what does soft stop refer to?

Regards,

Brian

  • 0
    TI__Expert 4175 points

    Hello Brian,

    So my understanding is you would like to use 3 GPI to monitor 3 external power good signals and have other rails dependent on the 3 GPI signals, is my interpretation correct?

    If so, yes you can do this in the GUI.

    "Immediately" causes the rails to turn off immediately.
    "Soft Stop" will turn off the devices in their turn off sequence. (See section 4.17 on the on the below FAQ)

    UCD90xxx Family Frequently Asked Questions and Answers 

    Please let me know if you have any further questions.

    Regards,

    Samuel Gradinaru

  • 0 in reply to Sam
    TI__Expert 5310 points

    Hi Samuel,

    One question is about the how to deal with the transition stage.

    For example we have 3 PG signals transit from high to low( let's say from 111 to 000). Ideally we could set the corresponding power rail status for 111 and 000 . The problem here is there might be a timing difference for each pg signal to go low, so 3 PGs would not directly transit from 111 to 000, instead it may go to 110 ->100->000. Even the transition might be very fast, how can avoid that trigger other power rail status?

    Regards,

    Brian

  • 0 in reply to Brian Wang0
    TI__Expert 4175 points

    Hi Brian,

    So do you have configurations in between 111 and 000, or just the two configurations? We would need to see the how the states are arranged to determine if there will be a problem or not.

    Regards,

    Samuel Gradinaru