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BQ21040: BQ21040DBVR charger gets stuck on charging state

NirKe
Prodigy 20 points
Part Number: BQ21040
Other Parts Discussed in Thread: BQ25618, BQ25628

Tool/software:

We are charging 1 li-ion battery, 138mAH with BQ21040DBVR.
For an unknown reason, on rare occasions, upon connecting the charger to the battery, when the battery is charged the charger will indicate a 'charging' state and will stay stuck on it regardless of the charge current.
The ISET is currently 130mA, we are drawing far less than that from the charger.

what can be the source of the problem and how would you suggest to resolve it?

Thank you 

  • 0
    Prodigy 20 points

    Hi again,

    Additional information about the problem.

    The battery is connecting to the charger component through pogo pins, can the order of the battery pins connection create wrong indications from the charger?

    (For instance, if the GND is connected couple of milliseconds before the Vbat and NTC or the Vbat is connected a bit before the NTC and GND)

    We will welcome any suggestion.

    Cheers 

  • 0 in reply to NirKe
    TI__Guru 57781 points

    Hi,

    The pogo pins may add extra resistance on the charging path. Please try to connect the battery to the OUT pin and GND pin directly and see.

    Thanks,

    Ning.

  • 0 in reply to Ning T
    Prodigy 20 points

    We performed more tests and saw that the contacts minor vibrations during the attachment of the device to the charger circuit gets the BQ component stuck - usually in no charging mode even though the battery is connected to it. Even after the minor vibrations stop the charger is still stuck in no charging mode.

    Are there any other recommended charging components that are dedicated to handle pogo pins connections and its relevant challenges robustly? 

    Thanks 

  • 0 in reply to NirKe
    TI__Guru 57781 points

    Hi,

    Please try pogo pins with less parasitics.

    Thanks,

    Ning.

  • 0 in reply to Ning T
    Prodigy 20 points

    Thank you for your fast reply.

    We removed the pogo pins and still it happens when some vibrations happen on one of the pins (that now connect the battery directly without pogo pins).

    So we don't think it's the pogo pins quality and suspect that the BQ component experiences logic faults.

    We also found more posts in the forum about logic issues with this component. 

    Is there any other recommended charger for such wearables applications?

  • 0 in reply to NirKe
    TI__Guru 57781 points

    Hi,

    Please check BQ25618/619 and BQ25628/629.

    Thanks,

    Ning.

  • 0 in reply to Ning T
    Prodigy 20 points

    Thank you Ning.

    And if I may ask, what is implemented differently in those recommended options that makes them a better option?

    Cheers

  • 0 in reply to NirKe
    TI__Mastermind 40635 points

    What is the input and output voltage when this is happening? Can you provide a schematic?

    Regards,

    Mike Emanuel