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BQ35100: Sampling Rate for Accumulator Mode

Gabe Ausfresser
Prodigy 83 points
Part Number: BQ35100

Tool/software:

Hello,

We are planning on using the BQ35100 IC in accumulator mode to monitor state of charge of a Li-SOCl2 battery. To save power, we will only periodically wake up the system for tens of milliseconds at a time. We want to be able to accumulate the coulomb counter for that small duration.

When I look at the datasheet, Table 6.11 specifies that the coulomb counter has a conversion time of 1 second. In section 7.3.2.1, it also says that the device measures and updates voltage, temp, and current every 1 second. Does this mean that the accumulator will not be able to sample fast enough to account for our tens of milliseconds long awake cycle?

When I read section 8.2.2.6, it explains that the device is designed to work in a system where there is a period discharge pulse of tens of mA for tens of milliseconds. This seems to contradict the two specifications above.

Any clarification would be much appreciated.

Thanks,

Gabe

  • +1
    TI__Mastermind 27321 points

    Hello,

    The BQ35100 can accumulate charge during your tens-of-milliseconds awake cycles in ACC mode, despite the 1-second conversion time. The ADC integrates current continuously, so your short pulses will contribute to the total charge measured over the 1-second window. To ensure accurate accumulation, keep the device active for at least 1 second after each pulse to allow the conversion to complete before powering down. The design intent in Section 8.2.2.6 supports this use case, so there’s no contradiction in the datasheet.