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Original question:

BQ76930: Check the life cycle

BQ76930EVM: TIDA-01093 Q38 Vgs Over Voltage Risk check

Jack Zheng1
Prodigy 90 points
Part Number: BQ76930EVM
Other Parts Discussed in Thread: TIDA-01093

As showed in TIDA-01093 SCH ,  20S  BMS Demo, Please help  check  the DSG or CHG Mode ,the Q38 or Q39 Vgs over over voltage or not,  please explain it .Thank you!

If the MOS Q27,Q28 Q32,Q33 all on, then the Q38 VGS will increased to Vbat+ (short  to Vbat+)

when CHG, If the MOS Q26,Q29,Q30, all on , then the Q38 VGS will increased to Vbat+(short  to Vbat+) 

  • 0
    TI__Guru* 77333 points

    Hi Jack,

    When Q27, Q28, Q32, and Q33 are all on, the gate voltage of Q38 will not increase to Vbat+. The source voltage of Q32 must be a couple volts below the gate voltage of Q32 (~12V). There will be additional voltage drop across Q33.

    The same is true for the CHG FET Q39 - the gate voltage will be much lower than Vbat+. The source of Q30 will be a couple volts lower than CHG_B with additional voltage drop across Q31.

    Best regards,

    Matt