Need a circuit which charge the cap with small drop out

[barbar]

indication on power fail

I use a battery input which should charge a MCU (microchip) and also a cap (to keep the power for a small time when I take the battery out. I need that the battery charge the cap. at max (so P-MOSFET is good low drop out).
The problem is that I need an indication when I take the battery out.
Every design I try with mosfet I get the cap. voltage back infront of the MSFET, so I can't detect the power fail.
Is any one know a circuit which charge the cap with small drop out (better then a schottky) and at the some time make a buffer between the battery and the cap?

 

[IanP]

Re: indication on power fail

You can try to sense mili-current that flows from battery to cap/PIC by measuring voltage drop acrossP-FET (+ maybe small resistor).
Attached is an idea on how to do it using low power opamp..