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LP3947 problem

Mikhail Polyakov1
Prodigy 10 points
Other Parts Discussed in Thread: LP3947

Hello everybody .

I use LI-POL battery charger  LP3947, and faced with a strange problem :

When power input of IC  is unplug, voltage on it is equally the voltage on battery. It means that power input stay connected to battery. When I plug to this scheme switched-off  AC/DC charger,  It begin to consum current from battery,and IC become very hot.    Why can it be so ? What I do wrong ?  

  • 0
    TI__Prodigy 210 points

    Hi,

    When you unplug the power to the IC the internal FET should be off. There will be the possibility of a diode drop between the output and the input so reverse biasing the output to the input is not recommended. This may be happening when you are connecting the switched-off AC/DC charger. Please note also the apps diagram in the datasheet which shows external switch control for USB and AC/DC charger operation.

    G Roxburgh.