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BQ25713: Under OTG mode, why prochot pin is always low according to VDPM protect?

Wilson Guo11
Prodigy 570 points
Part Number: BQ25713

Hi team,

When BQ25713 OTG is EN, I can always see prochot turns low. And I found this is because VDPM protect is always on.

In my application, OTG voltage is 5V and Vin min(0x0A/B) is 3.2V. In my opinion, under this setting, VBUS detection should be 5V. Therefore, I can't understand why VDPM protect is triggered?

Look forward your kindly reply. Thanks a lot.

Wilson 

  • 0
    TI__Mastermind 25800 points
    Hey Wilson,

    Is this a custom board or one of our Evaluation Modules?

    Can you provide the register settings for the charger?

    And do you have more information about your test setup when you see this behavior, such as battery voltage, input voltage, system load?


    Regards,
    Joel H
  • 0 in reply to Joel Hernandez II
    TI__Prodigy 570 points

    Thank you, Joel. This phenomenon can be found in both custom board and TI EVM.

    Below is the setting of EVM test.

    Vbus is only connected to a Voltmeter, without a source or load. A battery simulator is connected to Vbat with 3.6V voltage output. Vsys generated 3.54V accordingly.

    Charger setting can be see as below: OTG voltage 5V, OTG current is 3A min input voltage is 3.2V

    After EN_OTG is set to 1, prochot is turn low. And prochot status register STAT_VDPM is set to 1. The waveform of prochot and VBus is as below:

     

    Anything more to provide you, please feel free to ask. Thanks in advance!!!

    Best regards!!!

    Wilson

  • 0 in reply to Wilson Guo11
    TI__Mastermind 25800 points
    Hey Wilson,

    The VDPM /PROCHOT flag is tripped whenever the input is not present AND the PROCHOT_PROFILE_VDPM bit is set (which it is by default). It cannot be deasserted just by reapplied a valid voltage. It must be manually cleared in the ProchotStatus Register, by setting 21h[7] back to 0.

    Now, if the PROCHOT_PROFILE_VDPM bit is set to zero in the ProchotOption1 register, the /PROCHOT pin will not be asserted for that type of fault.


    Regards,
    Joel H