I'm working on a wireless sensor network and would like to know what it would take to shut down the regulator during deep sleep.
- MCU: STM32L151C6T6
- Regulator: TPS63001
- Radio: RFM69HW
- LCD: some chinese ILI9341 TFT
- Batteries: 2xPanasonic NCR18650 Lithium in parallel
I'm planning on going 3.3v, because I will allow the user to push a button to display readings locally on an LCD and that is saying it needs 3.3v. Otherwise I would go lower. Everything else supports 1.8v.
So my question is, if I have a node deep sleep, can I set the EN pin on the regulator low and depend on either the power supply caps or the inductor to to retain enough power to keep the MCU alive so it can wake up in 5 minutes? How do I know how long I'll have? Should I throw in a supercap too? Is it even worth it to try to turn the regulator off, or when there is no draw will it not burn energy?
Peak current will be under 200mA. When sleeping, nothing should be running except the MCU in stop+RTC or low power run mode, which is, according to the datasheet, 1.2 uA and 9uA, respectively. I'm sure some inefficiencies in my design will require wiggle room.
Thanks a lot and any feedback on any of the above is greatly appreciated.