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BQ2057W: USE BQ2057 charger 8.4V two cell li-battery FZT788B or SI6475DQ are very hot

wancheng du
Prodigy 10 points
Part Number: BQ2057W

I used BQ2057WSN with FZT788B or SI6475DQ to charge 2 cell li-battery.the Vin 9V Rsns 0.1Ω. I test the charge current about 1.2A.but the FZT788B or SI6475DQ are very hot. how can I solve this issue. can you advise a p-mos to me.thanks.

  • 0
    TI__Genius 13700 points

    Hello,

    You are going to encounter similar issues regardless of what PMOS device you choose. The reason being that the PMOS device is the in-line regulating element for this linear charger. This means that if you battery voltage is down at 6V and you are charging at 1.2A from a 9V source there will be 3V across the PMOS device at a current of 1.2A meaning that it is dissipating 3.6W and as a result will get very hot.

    Have you considered using a switch-mode battery charger? This will be far more efficient and therefore not get nearly as hot.