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BQ25713: Register status when power on

Kai Lai
Genius 9381 points
Part Number: BQ25713


Hi Team,

I have some questions with BQ25713 need to double confirm with BU, thanks for teams help !

  1. Does the VBUS readback(0x26) will always read one time when the first time power on(adapter plug in) even when the register 0x3A bit6 =0 which mean EN_ADC_VBUS not enable??
    I use the EVM to do some experiment, I found VBUS will read at power on nonmother I enable the register 0x3A bit6 =0 or 1.
    And I think this is a normal work since charger need to read the VBUS to determine it should work in buck or boost and set the VINDPM limiting voltage. 

  2. If yes, then only VBUS will read once at power on or does the register REG0x27/26(), REG0x29/28(), REG0x2B/2A(), and REG0x2D/2C() will also read one time when the first time power on even we didn’t enable it ?

Thanks!
Kai 

  • 0
    TI__Expert 4285 points

    Hi Kai,

    What values do you got in #1? and what is the expected value? I suspect you are reading back default values.

    Best Regards,

    Linhong

  • 0 in reply to Linhong Qin
    TI__Genius 9381 points

    Hi Linhong,

    In EVM experiment, the value I read in VBUS readback(0x26) at the power on is what I set with the DC source, so I assume Charger will read VBUS at power on nonmother the register 0x3A bit6 is enable or not. 

    Kai

  • 0 in reply to Kai Lai
    TI__Expert 4285 points

    Hi Kai,

    No, you need to enable ADC first. Please make sure power is completely off (including battery) during your experiment.

    Charge checks VBUS during powerup, but not through ADC.

    Best Regards,

    Linhong

  • 0 in reply to Linhong Qin
    TI__Genius 9381 points

    Hi Linhong,

    Yes, I'm sure that the power is completely off (including battery) during my experiment.

    So charger will check the VBUS during powerup, then determine the input voltage limit and write into 0x0A register, but  it will not write the VBUS voltage into 0X26 VBUS readback register?

    So if I see the VBUS readback register had show the value at the power on it must be I enable the the VBUS ADC?

    Thanks for your reply. Sorry that I didn't have much experience on charger setting.

    Kai 

  • 0 in reply to Kai Lai
    TI__Expert 4285 points

    Hi Kai,

    All registers have default values loaded upon powered up. Those includes 0x0A and 0x26. All initial values are fixed per IC design and hardware setup, however you can change them after powered up.

    You have to enable ADC in order to have "valid" ADC reading.

    Feel free to let me know if you have further questions.

    Best Regards,

    Linhong