Grahamed.
In any MOS transistor has a parallel diode. Using these two transistor diodes included counter. Those. switch is closed is closed to all current trends. Current will not flow between the adapter and the battery.

 

I think its to do with the way the charger regulator is configured. I'm not sure I understand it but its listed on page 15 here.

Looking at page 15 does not help me. It seems (given my limited time, patience and understanding) that the current during DCM is caused by the inductor in the switch-mode regulator which is the subject of the app. note. No such inductor is present in #36.

The line-supply is generally on or off but I do see there could be a transient when current passes though the body diode after the FET is turned off as the line-supply voltage collapses but this can only happen if the line-supply is still higher than the battery.

The body diode generally never conducts, but if it did it would do as in the same way as a "real" diode in the simple case of the two diode-switch using two diodes and no FETs. Is anyone suggesting that these diodes behave badly (other than volts drop).

 

Hi,
You may use a voltage divider (10K-10K) to drive the mosfet gate .


Regards