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BQ51050B: WPC wakeup problem

BJ Han
Expert 2035 points
Part Number: BQ51050B

Dear TI,

The current problem is that when the battery is discharged naturally (when the cell voltage falls below 3.0 V)
When the battery voltage reaches 0V due to PCM circuit operation, it will not wake up when trying to charge wirelessly.
Also, when the PCM circuit operates, there is no change even if you try to charge wirelessly.
Is there a solution?

  • 0
    TI__Guru* 75656 points

    Hi BJ Han

    I can assist with this question.  Thanks for posting schematic, it looks OK.

    Do you have any info on the PCM?

    Would it be possible to send a scope capture of the BAT pin at start up?

  • 0 in reply to Bill Johns
    Expert 2035 points

    Dear Bill,

    Thank you for your attention and support.
    Sorry for the late response. I solved the problem well.
    There was a problem in biting the RECT signal to the MCU at random.

    One more additional help will be appreciated.
    We are using a small battery (250mAh), so we changed the charging current from 500mA to about 200mA.
    I think it works well, but in the data sheet, the charging current Ibulk minimum is written at 500mA.


    Do you have any problems? I would appreciate your feedback.

  • 0 in reply to BJ Han
    TI__Guru* 75656 points

    Hi BJ Han

    Thanks for the update, glad the problem is resolved.

    Regarding charge and termination current.

    The BQ5105X was designed with charge currents of 1A with termination currents of 100mA in mind. 

    Use at lower currents is possible but the accuracy of charge current and termination current will decrease. If termination current is 30mA or above you should be OK.  In your case 200mA charge current would work but termination at 15% or 30mA should work. 

    It has to do with measuring the voltage on ILIM as it gets closer to ground.  Voltage generated by 200mV on ILIM is not bad but measuring voltage generated by 20mA is more difficult.