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Original question:

BQ76930EVM: TIDA-01093 Q38 Vgs Over Voltage Risk check

BQ76930EVM: BQ76930EVM: TIDA-01093 DSG Circuit Check

Jack Zheng1
Prodigy 90 points
Part Number: BQ76930EVM
Other Parts Discussed in Thread: BQ76930, TIDA-01093

As showed in the TIDA-01093 BQ76930EVM,SCH  Page 4,   Changed  the DSG  circuit  with same function , Remove BAT+  Q27,Q28,Q32 circuit,   Let DSG_B directly drive Q33.  When battery Short protction test under higher current,  protection was triggered,  but  the Q34,R90,Bq76930 always failed . Please help give some suggestion to improve it . Thank you!

  • 0
    TI__Guru 54715 points

    Hi Jack,

    If you drive Q33 directly you loose the SCR effect of Q34 & Q37.  You will need to figure out how a transient is getting to the damaged components.

  • 0 in reply to WM5295
    Prodigy 90 points

    Could you please help explaint the " loose the SCR effect of Q34 & Q37?", Then i keep the circuit or not, ?  The circuit contain: R90,Q34,Q37,R153 . Thank you!

  • 0 in reply to Jack Zheng1
    TI__Guru 54715 points

    Hi Jack,

    If you have connected directly to Q33 then the DSG pin can't pull down Q34 base which is what triggers the turn off circuit.  I don't see why the R90 or BQ76930 would fail.  Generally resistance between the DSG pin and the FET drive will provide some protection.  Have you monitored the voltages during the event?  It would seem you have some high voltage coupling to R90 or the DSG pin.  Can you share your schematic?