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BQ24296M: battery removal detection

Part Number: BQ24296M

Hi!

We've selected BQ24296M for one of our devices, but for passing a relevant certification we need such feature as battery removal detection (unit should show battery fault when the battery was removed).

Since there is no such feature in the IC itself, our engineer suggested three possible ways:

  • the IC shows repeatable strobe signals on INT/STAT pins when the battery was removed.
  • we can use additional circuits to control the battery's NTC (and it's complicated to distinguish battery removal from extreme temperatures)
  • for a short period: turn BATFET off, turn VBAT discharge circuit, measure VBAT

It would be nice if you could provide us some additional information about solutions for battery removal detection. For now, it isn't clear to us:

  • if strobe signals detection is the correct way to do this
  • if we can periodically turn off BATFET AND if it won't destroy the battery itself (we have previous experience with another charger IC which had current spikes during startup, they were able to destroy battery in 1-1.5 years of normal operation)

Our devboard's schematic:

  • Hi,

    There are multiple conditions for INT pulses and STAT on/off. INT/STAT are not reliable signals to detect the battery removal.

    Turning BATFET on/off periodically is ok as long as the BATFET on/off voltage/current transients do not exceed the specifications defined on the d/s. The BATFET on/off voltage/current transients are dependent on the transient levels, transient time, PCB layout etc which are out of control of the charger.

    Thanks,

    Ning.