I 've built an MCP1640 circuit powered by a 1.5V single cell battery. (no microcontroller in the circuit)
I want to start it up and shut it down with a single push button.
But the battery voltage starts from 1.5V and goes down to 0.35V (till the battery gets totally empty).
I was thinking something like this (which definitely won't work with e.g 0.7V battery voltage):