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UCD90120A: One of power rail enable pin did not asserted after power cycle

user6530578
Prodigy 40 points
Part Number: UCD90120A

Hi

I setting the rail#2 ROV_Core Enable (Pin17 GPIO5) is follow rail#1 (P3V3) to output high.

But now when rail#1(P3V3) is powered down then up, the rail#2  ROV_Core enable pin is keep low.

Note: UCD90120A VCC is alive during the power cycle.

I insert my code & issue waveform

  • Power Cycle DOWN

  • Power Cycle UP

UCD90120A 2.3.4.0 Address 52 Project File_NCP1-1_PVT_R03_20201202.xml

  • 0
    TI__Guru 58020 points

    8540.UCD90xxx Quick Guide.pptxHello

    Have you set the rail#2 as fault shutdown slave of rail#3? rail#2 will not follow#rail3 unless it has been set.

    setting sequencing on/off dependencies does not shutdown rail#2 when rail#3 is off.

    Please review the sequencing and fault shutdown slides in the attachment.

    Regards

    Yihe

  • 0 in reply to yihe
    Prodigy 40 points

    Hi yihe

    I solve my question by change rail#1 Fault shuts down due to fault ,turn off these rail as well setting : Close AVS_COE(rail#12)

    Becauce our new design unuse AVS_CORE this power. So we try to close this setting base on code : UCD90120A 2.3.4.0 Address 52 Project File_NCP1-1_PVT_R03_20201202.xml

    And then we can solve rail#2  ROV_Core enable pin is keep low issue. But I did not know this change will solve it?

    Chould you help us? Thanks.

  • 0 in reply to user6530578
    TI__Guru 58020 points

    Hi

    I am not quite clear about what you want to achieve here.

    The enable of Rail#2 is ACTIVE HIGH. if its stays at low, there are two possibilities; 1. the PMBUS_CTRL signal is not asserted/3V3 is not above its POWER_GOD threshold.2. rail#2 was shutdown due to fault.

    if rail#2's enable never goes high after the board is up, you have to look PMBUS_CTRL and rail#1

    If rail2's enable changes from high to low at some point, it is due to a fault. but looking your project file, I do not see there is any fault response set.

    So you may need check PMBUS_CTRL and rail#1's voltage.

    Regards

    Yihe

  • 0 in reply to yihe
    TI__Guru 58020 points

    Hello

    We haven't heard from you for a while and assumed that the issue has been solved. Please reply if any further help is needed.

    Regards

    Yihe