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DM3725 and TPS65950 power down(shut down) sequence

Raviraj Somnache1
Intellectual 430 points
Other Parts Discussed in Thread: DM3725, TPS65950

Hi,

We are using DM3725 and TPS 65950 based customized device and facing some issues with power down(shut down).

We tried to shut down device by writing 1 to TPS65950 register P1_SW_EVENTS (0x46), with this device is shutting down but we are getting VBAT current 3mA.

We also tried by configuring all regulators  REMAP registers to 0 but no luck, observation is same 3 mA current.

Can anyone let us know whatever we followed to shutdown is correct or not ?

If SW step is correct then how we can debug HW level, which are components  or test points we need to test to find out HW leakage current.

Thanks,

Raviraj

  • 0
    TI__Genius 17380 points
    Hi Raviraj,

    Setting DEVOFF to '1' should initiate the ACTIVE--> WAIT-ON transition at which point the PMIC should use approximately 64 uA of current at 3.8V input, so I see your concern.

    Does VBAT connect to anything other than the PMIC? If so, can we remove those connections to ensure that only the PMIC current is being accounted for.

    What is connected to the VRRTC supply? If it is drawing 3 mA that could explain the 3 mA observed.

    Is the device staying in WAIT-ON state? If there are any pending switch-on requests then the PMIC will go back to ACTIVE state. This can be checked by checking whether regulators stay OFF or initiate the WAIT-ON to ACTIVE transition.

    Is the backup battery charger enabled/disabled? That can contribute up to 1 mA.

    If you haven't taken a look at the Technical Reference Manual (www.ti.com/.../swcu050), it has a ton of useful information.
  • 0 in reply to Kevin LaRosa
    Intellectual 430 points

    Thanks for your inputs.

    Multiple supplies derived from VBAT but all ICs are controlled by VIO_1V8 and GPIOs.

    One more observation is VIO_1V8 voltage is 0.15mV after shut down and  back battery voltage (BKBAT) also shows 0.25mV.

    I have given all this inputs to our HW team to check on this, may be HW issue. If you have any inputs please let us know.

    Thanks,

    Raviraj

  • 0 in reply to Raviraj Somnache1
    TI__Genius 17380 points
    Hi Raviraj,

    My biggest concern is OFF current of the other components and this potential back-biasing of the VIO_1V8 from one of these components. If hardware team can isolate each component then that may help to identify where the leakage is going.