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Original question:

AM57x short on 3 power supply rails

TPS659039-Q1：TPS659039 output short circuit

user3378603
Intellectual 1000 points
Part Number: TPS659039-Q1

Hi,

The PMIC chip of one of our debug boards was damaged during use and we are troubleshooting the cause. We want to know which PMIC internal conditions will affect the normal output voltage of the SMPS9 channel ？

the SMPS9_IN has a normal 3.3V voltage input, but after the POWERHOLDG is powered by 5V, the SMPS9 channel does not have a 1.8V voltage output. As we know,  SMP9 is the first power-up sequence after the POWERHOLD pin of O9039A387IZWSRQ1  is enabled.  

In addition,we have removed the SMPS9 load circuit, including the Path which SMPS9  power to VIO_IN , but it is useless.

  • 0
    TI__Genius 10000 points
    Feng,

    Do the other rails power up correctly? If so, can you read the INT status registers and see if any interrupts are generated?

    Thanks,
    Nastasha
  • 0 in reply to Nastasha
    Intellectual 1000 points
    Hi Nastasha,

    I2C pull-up resistor is powered by SMPS9, all outputs of PMIC have no voltage, VIO_IN is not powered, so INT status registers cannot be read.
  • 0 in reply to user3378603
    TI__Genius 10000 points

    Feng,

    This looks like it is not SMPS9 that is the issue if all rails are not turning on. If POWERHOLD is high and the device is not turning on, there may be a few possible issues:

    1. Is a "Gating ON Request" present? This keeps the device off.

    2. Is an "OFF Request" present? This keeps the device off.

    These lists of requests are also in the datasheet. If the device is damaged, you may not be able to tell what internal condition is keeping the device off. How did you confirm the device is damaged? Was a short measured somewhere? Was there visible damage to the PMIC or external components?

    Thanks,

    Nastasha

  • 0 in reply to Nastasha
    Intellectual 1000 points

    Hi Nastasha,

    We are not sure that it is damaged, because the voltage measured on these pins of the PMIC is normal after power-on operation, and there is no heat and visible damage on the surface of the PMIC chip. 

    PWRON =High level 3.3V
    RPWRON =High level 3.3V
    PWRDOWN =Low level 0 V
    RESET_IN =High level 3.3V
    VCC1 =High level 3.3V
    POWERHOLD=High level 5V

  • 0 in reply to user3378603
    TI__Genius 10000 points

    Feng,

    Do you have issue with all your devices not starting up or only one? The voltages of your input pins look good. I do not see any issue with on requests. Have you probed VRTC? Is it stable at 1.8V?

    Thanks,

    Nastasha