I'm building a small circuit that needs to be powered by another device. I will power my own circuit from the already existing devices battery. I need to be able to shutdown/power-up my circuit through a trigger signal from the already existing device. My circuit needs ~200mA and at least 3.3V.
The only "trigger" signal available is a 3.3V signal, capable of providing something like 5mA.
When the existing device is powered off, the "trigger" signal will still have a small voltage, around 0.8V, so my idea is to use an opamp as a comparator, so when the "trigger" signal is higher than ~1.5V it will activate the power to my circuit, and when it´s lower than 1.5V it will shutdown my circuit.
I´ve attached a simulation of my idea and it seems to work, but i don´t know if this is the best approach to solve this.
Do you guys have any suggestions/changes, or maybe I should scrap my whole idea and do something else?
I´ve used transistors in this schematic, maybe it´s better to use mosfets? Any suggestions?