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Question about the V_drop out in BO24203

Michael Shen
Prodigy 10 points
Other Parts Discussed in Thread: BQ24203

Dear All:

       V_dropout  = Vin-Vout.  so, when I use Vin=12V, Vout=4.2V @ BQ24203, its V_dropout should be 12-4.2=7.8V.

is that right ?  or I have a wrong understnad about the V_dropout ? because in the 3rd page of the data sheet, its

 V(do) is typically=350mV; that confused me! 

  • 0
    Guru 192875 points

    Hi,

    I just looked into the datasheet and to my amazement I noticed the same thing:

    I guess, a TI representative sheds some light on this issue!

    Regards,

    Gautam

  • 0 in reply to Gautam Iyer
    TI__Guru**** 160721 points

    Dropout voltage is the minimum voltage above VOUT that is required in order for the device to regulate VOUT, otherwise VOUT=VIN-IOUT*RDSON of pass element.  As long as VIN is above VOUT by VDO, your output will be regulated UNLESS the power lost across the pass element (Plost=(VIN-VOUT)*IOUT) causes the IC to start thermally protecting itself by reducing IOUT.