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BQ76940： For battery management, BQ76940 only for discharge, what about charge?

shen yue
Prodigy 60 points
Part Number: BQ76940
Other Parts Discussed in Thread: BQ77915

I have checked the datasheet of BQ76940, and found for the hardware protection features, 76940 only could give protection when battery discharge, and I want to know, for the charge condition, overcurrent and short circuit, BQ76940 could give protection?

  • 0
    TI__Guru 54715 points
    Hi Shen,
    The bq76940 does not provide overcurrent protection in the charge direction. The expectation is that this would be monitored by a connected MCU which would certainly have some response time in addition to the 250 ms availability of the current reading.
  • 0 in reply to WM5295
    Prodigy 60 points
    Hi WM
    Do you mean, if I want to protect the battery at charge direction, I need another MCU to monitor.
    for the 250ms, I think a little bit longer, 250us?
  • 0 in reply to shen yue
    TI__Guru 54715 points
    Hi Shen,
    Correct, the MCU must monitor charge current. The bq76940 does not work without a MCU.
    Since the MCU would not be synchronized with the bq76940 it may take up to 2 scheduler cycles to get a current reading since the MCU may have just missed the start of the first cycle when it writes an enable. So if it just missed the cycle start, the measurement starts at 249.9 ms and the measurement takes another 250 ms. Plus tolerance.
    For a system which does not need an MCU, consider the bq77915 protector.
  • 0 in reply to WM5295
    Prodigy 60 points
    HI WM5295,
    Thank you very much!