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TPS659037 Shutting Down After Power-Up

AM5728_User
Prodigy 250 points
Other Parts Discussed in Thread: TPS659037

Hello,

We made a design using TPS6590377ZWST and AM5728BABCXEA.
I am trouble shouting one board with the following symptoms:
  • The board was powering up correctly on Friday
  • The board was not powering up this morning
  • PMIC output rails were all to 0V except VRTC_OUT
  • When I maintain PWRON or RPWRON shorted to GND, the board powers up for few second then shuts down
  • When I briefly short PWRON or RPWRON to GND, the board powers up for few second then shuts down
The configuration of the board is:
  • GPIO_7 is pull up to VRTC_OUT (via 0 ohm)
  • BOOT0 = 0
  • BOOT1 = 1
  • PWRON is floating
  • RPWRON is floating
  • POWERDOWN is pull down to GND (via 10 Kohms)
  • NSLEEP is pull up to VRTC_OUT (via 10 Kohm)
  • NREWARM is pull up to VRTC_OUT (via 100 Kohm)
  • VPROG is pull down to GND (via 0 ohm)
  • RESET_IN is pull up to 5V (via 0 ohm)
The intended behavior is that the board is always on. The board power ON/OFF is made by input voltage monitoring using circuitry TPS3808G01DRVR as per suggested by TI.
I have few other boards that seems to work properly.
In my comprehension, it follows indications from Design guide (TPS659037 Design Guide slia088 sept2015.pdf) section 2.6.1 with POWERHOLD always pull up and PMIC_RESET that is used as ON/OFF command.
Do you have any clue to fix the problem?
Thank you for your help
  • 0
    TI__Genius 16410 points
    Hello,

    When you say "powers up for a few seconds", could you measure how long the time is from power-up to shutdown? This could give us some insight in to what is happening. After power-up, POWERHOLD/GPIO_7 needs to be set within 8 seconds or else the PMIC will shut down, so if the power-on lasts 8 seconds, then this seems like the likely source. If it lasts 12 seconds, it is likely from PWRON being held low, since the PMIC will shut off after 12 seconds of PWRON being held low.

    I would suggest double checking the GPIO_7 voltage, very close to the pin. Pulling GPIO_7 high (1.8V logic) will turn on the PMIC, so the fact that it doesn't turn on indicates to me that GPIO_7 isn't getting set properly. And VRTC should be 1.8V, so please double check that since it powers the digital logic.

    Regards,
    Karl
  • 0 in reply to Karl Wallinger
    Prodigy 250 points

    Hello Karl,

    Thank you for the advice.
    The board is shutting down after exactly 8 sec. I probed GPIO_7 and the voltage was 0.
    After visual inspection it appeared to be a soldering issue on the pull down resistor.

    Thank you for your help, problem solved!