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Original question:

BQ25898: STAT Low at discharge state

BQ25898: Fast charging operation in DPM

Toshiro Imi
Expert 6960 points
Part Number: BQ25898

Hello,

While our customer evaluate bq35898 EVM and have some question about "Fast Charging " condition. As shown in the evaluation result, the charging status show "Fast Charging" even though DPM and supplement mode.

When we read the I2C resisters, then IINDPM status=IINDPM, VINDPM status=Not in VINDPM, battery voltage=3.684V, SYS voltage=3.664V in page-1, IINDPM status=Not in IINDPM, VINDPM status=VINDPM, battery voltage=3.644V, SYS voltage=3.624V i page-2. However the charge status is "Fast Charging" in both cases.

could you help him following questions.

- In DPM state of IINDPM=1 or VINDPM=1 case, is displaying "Fast charging" (STAT=Low) normal bq25898 operation ?

- In DPM state of IINDPM=1 or VINDPM=1 case and battery discharging state, is displaying "Fast charging" (STAT=Low) normal bq25898 function ?

best regards,

bq25898 STAT 20200806.pdf

  • 0
    TI__Guru 54651 points

    Imi-san,

    The observations are normal. The device does not have status bit indicating "Supplement mode".

    Thanks,

    Ning.

  • 0 in reply to Ning T
    TI__Expert 6960 points

    Ning-san,

    Thank you for your feedback. let me summarize DPM operation again.

    - once bq25898 is working into DPM (VBUS power applied, IINDPM=1 and/or VINDPM=1. SYS current is driven by VBUS with decaying charging current, or SYS current is driven by the battery in case SYS current is exceeded VBUS supply current capability.), Charge state is always "Fast charging".

    - once the charging state is in "Fast Charging", STAT output is Low.

    please correct me, if my understanding is incorrect.

    best regards,

  • 0 in reply to Toshiro Imi
    TI__Guru 54651 points

    Hi,

    Your understanding is basically right.

    Thanks,

    Ning.

  • 0 in reply to Ning T
    TI__Expert 6960 points

    Thank you for your help.

    Best regards,