I'm hacking my way through a LiPo charger that is sensitive to being plugged into a supply; I'm shooting to have it automatically disconnect from the load when in charge mode and automatically switch back to duty mode when unplugged from the charger. I'm not entirely sure I understand MOSFETs (I'm actively reading, don't worry). Especially whether or not I'm using the depletion MOSFET correctly.

The circuit is around the MCP73213.

Again; hack, and comfortable with it. But I'll take any criticism with thanks.

 

Maybe this would do: Assumes that with AC adapter removed, the input will fall to 0V. From memory, FDS9435 RDS 80 mΩ @ - 4.5 V on gate., also it is SM , but just about any similar P- FET should do.