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BQ25185: Device stops charging but does not raise STAT2

Jason Jibrail
Prodigy 10 points
Part Number: BQ25185

Tool/software:

I have a BQ25185 and single LiPo Cell.

One one board, charging seems to stop before the cell is charged.

On normal boards I see the current drop to the taper current of around 25mA and then step to 0.00mA and STAT2 goes high (STAT1 is also HIGH)

On the one board, charging works fine in the CC region, with the charge limit of 250mA.
Once the charger starts tapering, it gets to between 80 and 120mA and then steps to 0mA
STAT2 stays low and no further current flows into the cell.

After 6 hours STAT1 goes low as the charge timer expires.

What hardware issues can cause this early termination behaviour?

I have checked the TS/MR pulldown is 10k and reflowed the passives around the part.
 

  • 0
    TI__Expert 8225 points

    Hi Jason,

    Thanks for reaching out. STAT1 being HIGH and STAT2 being LOW when the charge current goes from 80mA-120mA to 0mA indicates that the charger has not terminated charge and no faults are present. Since the issue occurs on only one board, it suggests there is something about this one board or setup that's causing the issue.

    Could you check whether the battery is making good contact with the board? Is the connection loose? Is each board using its own battery? Does the issue persist if a known good battery pack is connected to the board with the issue?

    The most direct way to isolate the cause would be to perform an A-B-A swap, which is more involved but will determine whether the IC or the board is the problem:

    (A) Remove the suspect part (A) from the original failing board.

    (B) Replace the suspect part (A) with a known good part (B) and check if the original failing board now works correctly.

    (A) Place the suspect part (A) onto a known good board and see if the issue follows the part.

    Please let me know what you find.

    Best regards,

    Alec