BQ24078: Power dissipation equation

Ted Thomas1

Prodigy 135 points

Part Number: BQ24078
Other Parts Discussed in Thread: BQ24076, BQ24070

Equation on page 33 of data sheet is:

P = [V(IN) – V(OUT)] × I(OUT) + [V(OUT) – V(BAT)] × I(BAT)

I think it should be this:

P = [V(IN) – V(OUT)] × I(OUT) + [V(IN) – V(BAT)] × I(BAT)

Current to the battery comes from Vin not Vout.

over 7 years ago

0 Bill Johns over 7 years ago

TI__Guru* 75676 points

Hello
I think this is correct, but double checking.

0 Bill Johns over 7 years ago in reply to Bill Johns

TI__Guru* 75676 points

The bq24076 / 78 data sheet Power dissipation equation (9) on page 33 does not take into account battery current thru Q1 only current supplied to OUT pin. This will equation will be updated.

An accurate equation can be found in bq24070 / 71 data sheet, equation (10) page 24. See below.

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BQ24078: Power dissipation equation