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GG IC for 18mAH cell

Katsuhiro Kanao
Intellectual 1710 points
Other Parts Discussed in Thread: BQ27426, BQ24726

Hi team

Is there any GG IC for 18mAH Li-ION battery cell ?

best regards K.Kanao

  • 0
    TI__Genius 14985 points
    Hi Kanao-san,

    bq27426 is one of the lowest power gauges we offer.
    bq27621 has also been used with tiny batteries and is relatively low power.
    Even the normal current consumption of the IC might drain such a tiny battery over time, so there is another technique which you can use.
    If you send the SHUTDOWN command sequence to the gauge it will go to very low power mode. Then you can use the GPIO pin to wake it up once per hour (for example), allow it to initialize the SOC, then 10 seconds later you can put the gauge in SHUTDOWN mode again. This will result in average current consumption of the gauge <1uA and it will maximize the run-time of your battery.
  • 0 in reply to dMax
    TI__Intellectual 1710 points
    Regarding to gauging, does bq27426 have enouhg accuracy ?

    best reards K.Kanao
  • 0 in reply to Katsuhiro Kanao
    TI__Genius 14985 points

    Hi Kanao-san,

    For capacities <200mAh you should trick the gauge by multiplying all mA, mAh, cW, and cWh settings in Data Memory by 10x.   Then calibrate the current by 10x (enter -1000mA but is an actual current of -100mA.   Also, a sense resistor with a large value should be used to ensure the tiny currents have enough signal to be measured by the coulomb counter.  But if the currents are very tiny relative to the cell then perhaps the current measurement accuracy will not be so important as you can rely on the voltage updates.  If you plan to use the duty-cycle scheme then you only need to measure current accurately in the charge direction.  

    What is the old profile and use case of the battery and system?  It might require special tuning of the gauge  but it can probably work.  

  • 0 in reply to dMax
    TI__Intellectual 1710 points
    Hi dMax

    Thank you for your reply.
    Your recommendation GG is bq24726.
    Would you please let me know how to set 10x in Data Flash of this IC.
    This GG is ROM version, so I wonder that Data Flash could change.
    I would appreciate to suggest the operation method more detail.

    best regards K.Kanao