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TPS650861: emergency shutdown

Michael T Schneider
Expert 3790 points
Part Number: TPS650861

Team, I have been having an issue with TPS650861 the where it goes into emergency shutdown

I believe we have been able to determine the root cause of the PMIC going into emergency shutdown.

Unfortunately it was a mistake on the design as we did not tie PIN VTT(Pin 46) of the VTT LDO to buck 6.

Buck 6 setpoint is 3.3V, and Pin VTT is connected to Buck5 output, which is set to 1.2V. With this configuration, the expected output is Buck6/2 = 1.65 V, so it never enters the expected regulation band and shut down 10ms after being enabled.

I believe that my only options at this point are to re-spin the board, or to wire in an external LDO. Can you confirm that there is nothing else that I can do through the I2C interface? Unfortunately, I don’t have the c orrect adapter yet, but it will be in today sometime.

  • 0
    TI__Genius 12735 points

    Hi Michael,

    Are you planning to change the output set point of Buck 6 or VTT? The issue here is VTT must be 1/2 of the Buck6 output as the regular is internally referenced to the feedback of Buck6. There may be some ways to modify the feedback for the VTT LDO to have the output match your original setting however these will be outside of the normal operation of the device and may result in behavior not specified in the datasheet.

    Best regards,

    Layne J