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BQ24171: Needed AVCC off period for device reset

K. Sasaki14
Guru 10200 points
Part Number: BQ24171

How long period should we off the AVCC for device reset?

Is bq24171 done reset if AVCC drops below 3.37V even for a moment? Or should we wait for a while?

If we should wait, please let me know the period.

Best Regards,
Kohei Sasaki

  • 0
    TI__Guru**** 166106 points

    Hi Sasaki-san,

    The deglitch time for ACOV and ACUV is 30ms typical.  I suggest adding 25% for maximum so 30ms*1.25= 37.5ms.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Guru 10200 points

    Jeff-san,

    Thank you for your support.

    However it is protection function on OVPSET pin. I would like to know about UVLO on AVCC pin.

    Whether bq24171 is done reset if AVCC drops below 3.37V even for a moment, or we should wait for a while?

    I would like to know AVCC off period for proper initialize.

    Best Regards,
    Kohei Sasaki

  • 0 in reply to K. Sasaki14
    Guru 10200 points

    Jeff-san,

    Sorry for pushing you.

    How is the progress about this post?

    Best Regards,
    Kohei Sasaki

  • 0 in reply to K. Sasaki14
    TI__Guru**** 166106 points

    Hi Sasaki-san,

    OVPSET senses voltage for ACOV and ACUV.

    There is no mention of deglitch for UVLO in the original spec so the response time is the comparator response time in the <10us range.  The UVLO comparator at AVCC pin is the last resort to disable the IC, following ACUV (since AVCC pin response to input droop is delayed by the RC filter compared to what OVPSET senses) and then the SLEEP comparator. 

    The input undervoltage, ACUV (d/s page 9), has a deglitch of 30ms.  The SLEEP comparator, which trips if VACC<VSRN+90mV, has various levels of deglitch per d/s page 8.

    Regards,

    Jeff