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Any 1S Li-Ion gauge able to distinguish between >500 uA = NORMAL current and <50 uA = SLEEP current?

Jonathan Bender
Expert 7895 points
Other Parts Discussed in Thread: BQ27621-G1, BQ27421-G1

Hello,

Are there any single cell gauges capable of distinguishing between > 500 uA for NORMAL current and <50 uA for SLEEP current?

I have a very small (< 75 mAh) battery. Gauges like bq27621-G1 and bq27421-G1 seem like a good fit, except it appears that the Sleep Current for these cannot be below 1 mA. In this use case, the system spends a lot of time in an 'idle mode' that draws between 0.5 and 1.5 mA, and I'd like to keep the gauge active in this state to keep the state-of-charge as accurate as possible.

From bq27421-G1 TRM p30:

Thanks,

Jonathan

  • 0
    TI__Mastermind 24870 points
    Hello Jonathan,

    How big is the battery of the device? The bq27421 has a coulomb counter and might not be able to distinguish between the two current consumption modes. However, if there are changes in the voltage, then the bq27621 will be a better fit.

    Thanks,
    Kang Kang
  • 0 in reply to Kang Kang
    TI__Expert 7895 points
    Hi Kang,
    The battery is between 30-70 mAh. Would bq27621-G1 be able to stay in NORMAL mode with load currents of 500 uA, and transition to SLEEP mode when that current drops below 100 uA?
    Jonathan
  • 0 in reply to Jonathan Bender
    TI__Mastermind 24870 points
    Hello Jonathan,

    Is it possible to ask the customer to provide a voltage profile of when the current is 500 uA transitioning to below 100 uA?

    Depending on the internal impedance of the small cell, this might be a very hard application to handle.

    The discharge rates vary between C/700 to C/140. Both of these discharges are negligible to the size of the battery.

    What is the end application?

    Thanks,
    Kang Kang