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Original question:

TPS23861: what will happen if I disable current sensing feature

TPS65217: SYS1/2 (pin 7&8) are 1.0V in my board

Chris Zhao1
Expert 1240 points
Part Number: TPS65217
Other Parts Discussed in Thread: AM3352,

Hi experts,

I'm using TPS65217C to power on AM3352 in my board, generally speaking it worked well, but I found one board having issue with it.

The AC pin (pin10) is 5V, but the SYS pin (7&8) is like 1.0V, so it could not power on AM3352, I was wondering there was some kind of short in AM3352, but after measuring the resistance, it seems not. 

Can you give some suggestions?

Regards

Chris

  • 0
    TI__Mastermind 30280 points

    Chris,

    Did you try pressing the Push-Button connected to PB_IN of the TPS65217 PMIC?

    Have you read the application note titled "Designing Robust TPS65217 Systems for VIN Brownout"?

    It sounds to me like one of a couple things is happening:

    PWR_EN is never set high. If this is the case, then pressing the push-button should turn the system back on.

    PWR_EN is set high, but after a power cycle the system encounters an issue due to a brownout on VIN. If this is the case, pressing the push-button will not work. You will need to completely power-down the system (AC=0V for >1s) before applying power again.

  • 0 in reply to Brian Berner
    Expert 1240 points

    Brian,

    Thanks for helping.

    I pressed the button, it didn't work.

    The right sequence should be:

    1) 5V is available, then VLDO1 of TPS65217 is available,

    2) VDDS_RTC of AM3352 is powered by VLDO1, which is 1.8V, once this 1.8V is available, AM3352 will drive PWR_EN high.

    3) Then the other power rails of TPS65217 will be up.

    While in this broken board, the SYS1/2 is 1.0V, in this way, the VLDO1 (1.8V) will not be available, so the PWR_EN signal will just be a pulse in my board.

    Regards

    Chris

  • 0 in reply to Chris Zhao1
    TI__Mastermind 30280 points

    Chris, 

    When the board is broken, measure VIO.

    If VIO is not 0V, then you are back-feeding power to the TPS65217 PMIC.

    This could be the cause of the issue.