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BQ24250: Charging wont stop

M.A.M
Expert 8535 points
Part Number: BQ24250
Other Parts Discussed in Thread: BQ25618

Hi,

Please help me assist my customer (offline if needed) that see the following strange behavior.
Your expertise is needed. Thanks!

B.r / M.A.M

"Currently the battery charger on our design does not stop the charging (change status become complete) even though the charging current is already below the configured termination value (in this case 50).
The timer fault occurs, so in that case we could not differentiate between good and defect battery.
The battery is perfectly healthy one.

Below is our charger configure
    properties.watchdogEnable = false;
    properties.currentLimit = Charger2000;
    properties.statEnable = true;
    properties.chargeTerminationEnable = true;
    properties.chargeEnable = true;
    properties.hiZEnable = false;
    properties.regulationVoltage = 4040; //!< 4040 mV, around 1000mAh on fresh battery
    properties.chargeCurrent = 900; //!< 900 mA
    properties.terminationCurrentThreshold = 50; //!< 50mA
    properties.lowChargeEnable = true;
    properties.dpdmEnable = false;
    properties.vdpm = 4200; //!< 4200mV
    properties.slowTimerEnable = false;
    properties.timerLimit = Timer6H;
    properties.sysoffEnable = false;
    properties.tsEnable = true;
    properties.ovp = OVP6V5;
    properties.clearVdp = true;
    properties.forceBatteryDetect = false;
    properties.forcePtm = false; "

  • 0
    TI__Guru*** 148825 points

    Hi M.A.M,

    What is the measured value at BAT pin?  Can you provide status register values?  The charger automatically disables termination if any of the other DPM loops (VINDPM, IINDPM, thermal) are active.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 50 points

    Hi Jeff,

    M.A.M is helping on my issue.

    Measured battery on fully charged condition is around 4.03 volt.

    I have a MCU connected to the charger to configure it and pull the parameters.

    These are my charging sequence.

    • Initial configuration I set registers [1-7]: 0x00, 0x5C, 0x6C, 0x42, 0x20, 0x28, 0x30
    • Charging starts, I disable LOW_CHG on register 5 and set charging current become 500mA (our system have 2 options 900/500mA). Pull registers status return 0x10, 0xDC, 0x6C, 0x02, 0x00, 0x28, 0x20.
    • After 30 minutes we enable LOW_CHG on register 5. Pull registers status return 0x10, 0xDC, 0x6C, 0x02, 0x20, 0x28, 0x20.
    • Charging continues even the current is below the termination setting until safety timer triggered (6 hours).
    • Timer Fault occurs. Pull registers status return 0x37, 0xDC, 0x8C, 0x02, 0x20, 0x28, 0x20.

    As you can see none of the DPM loops is active (register 5) and I don't enable it at initial configuration.

    Kindly share your advice for this issue.

    Thanks,

    Jefri

  • 0 in reply to jefri
    TI__Guru*** 148825 points

    Hi Jefri,

    Termination is automatically disabled when LOW-CHG bit is set.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 50 points

    Hi Jeff,

    I have tried it, and it works. The charging is stop once the current is below the configured value.

    I just need to disable low current charging. But is there any other way than disable it?

    I mean we want to keep low current charging if possible.

    Thanks,

    Jefri

  • 0 in reply to jefri
    TI__Guru*** 148825 points

    Hi Jefri,

    Unfortunately, there is no way to enable termination if low charge is enabled.  If you have an ADC or other circuit that can report when V(BAT)=VBATREG (i.e. the charger is in CV mode, meaning the current has likely already tapered below 325mA), you could then disable low charge mode for proper termination.

    We have a new charger, BQ25618 / 9 that has very low, very accurate charge termination and as well as low leakage in battery only mode.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 50 points

    Hi Jeff,

    I have tried your suggestion as well and the result is quite good, we have battery gauge on our circuit.

    Thanks for helping my issues Jeff and M.A.M, I really appreciate it.

    Regards,

    Jefri