Peripheral device power switch and MCU sleep

[Majek Ondrovic]

I have a project with an Atmega328pb at 3.3v 8MHz in communication with an SMD module ( a wireless lighting controller) over SPI. This whole project is lipo battery powered, and I want the MCU to sleep but remain powered so it can start almost instantly. The SMD module will need its power cut because it doesn't have a sleep mode- the module draws 60-250mAh variably.

What is the ideal power switch in this case? A dedicated IC or some MOSFET, etc..?

I've tested this manually by disconnecting the power to the module and then sleeping the mega328. I get about 8µA draw which is great. And then I have it wake up via an interrupt.

My understanding was that putting all the GPIO to input with internal pull-ups gives the least current draw in sleep mode. But then I've noticed most of the power distribution switch IC's are all active high so I'm not sure how to best deal with that. I was hoping to be able to have the MCU come out of sleep and pull the power switch ENABLE low to turn the module on.

Thanks in advance!