Latching power circuit

[TomV]

Hi,

Im building a power switch latching circuit for a project powered by a 3.7v LI-PO. Ive based the circuit on those by mosaic-industries. The circuit turns on and off fine, a hold of the button shuts the system down as expected. However when the MCU pin "SHUTDOWN PIN" is used to turn off the power, by switching to a LOW output signal as soon as the MCU shuts down the circuit is latching back on again and therefore "SHUTDOWN" pin goes high to maintain the latch until the next shutdown is requested, this behaviour loops.

The label here that says PWR_BUTTON connects through a momentary switch to GND. Battery is a 3.7v Li-Po pack. I've also tried the IRF7317PBF. Any advice would be great. Thanks.

[Peabody]

I don't really understand how the pushbutton part works.  A short press turns power on, and a long press turns it off?  Can you explain how it works?

I suspect what's happening with the pin turnoff is that as Vcc decreases it reaches the point where the processor shuts down and the low on the pin is released, but there's still enough voltage to turn  the N-channel mosfet back on through the resistors, and the processor reboots.  But that's just a guess.  I'm not sure how you would fix that without messing up the pushbutton part.