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TPS65218: AC_DET PIN causes PMIC to behave incorrectly

Fedex Hsu
Prodigy 10 points
Part Number: TPS65218

Tool/software:

Our platform uses PMIC TPS65218 and we have several units experiencing its abnormal behavior.

I describe the situation we encountered as follows.

  1. Pulling AC_DET to GND should be used to trigger the power on sequence, but these units cannot. They are normal to use the PB pin to bootup.
  2. When the system is operating normally, pulling AC_DET to GND will cause the system to shut down and PGOOD will also show the low voltage of logic 0.
  3. When PGOOD is at low voltage described in item 2, the voltages of DCDC1-4 and LDO1 are all normal.
  4. In addition, when the input power is normal and there is no trigger source, AC_DET itself will toggle continuously.

Have TI member ever encountered a similar situation or know what might cause this?

  • 0
    TI__Genius 9117 points

    Hi Fedex, 

    Could you clarify a few things so  I can get a better idea of what may be happening here?

    What is the full part number of the TPS65218 part you are using? (Ex: TPS65218D0 or TPS6521825)

    Is your system a battery-powered application?
    Can you clarify how AC_DET is connected in your schematic? Is it like A, B, or C, or something else:

    Is EN asserted high after AC_DET is being pulled low? Is EN pulled low at any moment?

    Fedex Hsu said:
    When PGOOD is at low voltage described in item 2, the voltages of DCDC1-4 and LDO1 are all normal.

    The device may be in the SUSPEND state, with DCDC1-4 and LDO1 enabled in standby.

    Looking forward to your response so we can figure out the root cause here. 

    Best Regards, 
    Sarah

  • 0 in reply to Sarah Lao
    Prodigy 10 points

    The full part number I got from our database is SNE8038D0RSLR and the datasheet is the same as that of TPS65218.

    Our application is type A.

    The behavior of the EN is a bit complicated, so I will describe it separately.

    (1) After booting by PB, EN is asserted high. At this time, AC_DET is pulled low, EN keeps high and PGOOD goes low. System shut down.

    (2) Pull AC_DET down to low to start up. The EN voltage is sometimes high and sometimes low, but the system cannot be started.

    Later I found that AC_DET and PGOOD are short-circuited, and I am sure it is not a manufacturing problem. What are the possible causes of this?

    Or there is sudden voltage input into which PIN will cause such a problem.

  • 0 in reply to Fedex Hsu
    TI__Genius 9117 points

    Hi Fedex, 

    Are you able to share your schematic so that I may review it for a better understanding?
    You may share over private message or email me at s-lao@ti.com if privacy is a concern. 

    Also are you using I2C in your system, and are you able to read any interrupts or flags in the registers?

    Best Regards, 
    Sarah