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BQ76952: REGIN Supply Path When MOSFETs Are Off

Yasir Ziya Gültak
Prodigy 50 points
Part Number: BQ76952

Tool/software:

Hello,


The collector pin of the transistor used to supply the REGIN pin is connected between the charge and discharge MOSFETs. In this case, if the MOSFETs are off and the MCU connected to REG1 is running, where will the current come from?
My guess is that it will flow through the body diode of the CHG MOSFET. If that’s the case, will this diode get damaged over time?

Thanks Slight smile

  • +1
    Intellectual 496 points

    Hi Yasir,

    Yes, if you are supplying REGIN from the common drain of the FETs, then it will get supplied through the body diodes of either the CHG FETs if the DSG FETs are OFF or via the DSG FETs if the CHG FETs are off. But this leaves a case in the event of SCD, when both FETs are OFF, your REGIN will not get any voltage and hence REG1 and REG2 will go off.

    As can be seen on some of the reference designs, the workaround for this will be to connect REGIN to CELL 16. I would recommend this if you are planning on using the REG1 to power your MCU.

    The answer to your question of any damage to the body diode of the FETs is no, you'll be absolutely fine.

    Best,
    Abhijith