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LP876242-Q1: Shutdown issue

user5883945
Expert 1806 points
Part Number: LP876242-Q1

Tool/software:

Dears,

The device operates normally at room temperature for a period of time, and there is a probability that 4 Buck circuits have no output. From the phenomenon, it should belong to IMMEDIATE SHUTTOWN. The voltage of Vout_LDO is normal, and it returns to normal after being powered on again. The MCU is powered by PMIC, so it is not possible to view the registers through the MCU. How to investigate shutdown caused by other reasons after excluding the causes of overheating and overvoltage。

       SCH

  • 0
    TI__Genius 16350 points

    Hi,

    Schematic looks okay and for the debugging I may need to ask few questions to get more understanding of the problem?

    1. Are you able to capture the shutdown on oscilloscope ? 

    2. From your statement it looks like initially the device powers up normally and then after sometime it goes to shutdown. Do you know after how much time exactly? and does the shutdown occur at similar time intervals or it is random?

    2. What do you mean by your below quoted statement ? do you mean BUCK4 only shutdown or did you mean all 4 bucks shutdown?

    user5883945 said:
    there is a probability that 4 Buck circuits have no output

    3. Can you share the device NVM ID and REV and also the top marking of the device ? 

    4. Can you share how many devices are failing?

    5. Any additional information that you can share ? Have you contacted your local TI representative in this regard?  

    BR,

    Ishtiaque  

  • 0 in reply to Ishtiaque Panhwar
    Expert 1806 points

    Hi 

    1. Are you able to capture the shutdown on oscilloscope ? 

     No, the power is shutdown and system power is down.

    2. From your statement it looks like initially the device powers up normally and then after sometime it goes to shutdown. Do you know after how much time exactly? and does the shutdown occur at similar time intervals or it is random?

    random.

    2. What do you mean by your below quoted statement ? do you mean BUCK4 only shutdown or did you mean all 4 bucks shutdown?

    all 4 bucks shutdown.

    user5883945 said:
    there is a probability that 4 Buck circuits have no output

    3. Can you share the device NVM ID and REV and also the top marking of the device ? 

    4. Can you share how many devices are failing?

    almost all

    5. Any additional information that you can share ? Have you contacted your local TI representative in this regard?  

  • 0 in reply to user5883945
    TI__Genius 16350 points

    Hi,

    Thanks for reply. 

    Without getting any scope shots how can you conclude that it is PMIC which is causing the shutdown. May be it is 3V3 input supply to PMIC which might goes off for any reason and as a result PMIC shuts down. 

    1. You need to probe by looking into the input supply of PMIC and output rails, nINT and nRST signal of the PMIC and try to capture that on oscilloscope to know what is happening. 

    2. Second, are you able to read out any interrupts or errors from the PMIC through SPI ? Without reading any information how can we know that PMIC is causing the shutdown and for what reason?

    Can you share the device TI_DEVICE_ID, TI_NVM_ID and TI_NVM_REV register bit information from the device that you are using. 

    BR,

    Ishtiaque