I am working on a very power sensitive application involving a STML431 processor running only off a battery. I plan on using Shutdown mode most of the time with an hourly wake up.
I am looking for 1 measurement (maybe averaging a few actual samples) every hour of the battery power supply and spending the rest of the time in Shutdown mode of STM32L4.
What is the most effective way of handling ADC to guarantee lowest possible power during shutdown.
1.) Is turning the ADC off enough? What is current draw with it turned off?
2.) Looking at spec it seems maybe I can turn off ADC and configure its pin as floating input before entering Shutdown, maybe that is best?
3.) Or, use an external switch/LDO to disable all input to ADC pin during shutdown
4.) Or, use internal VBATT ADC (since it is connected to same supply as VDD) measurement for very short periods of time during wakeup interval and then disable it ASAP to prevent current draw over its voltage divider.
Any information/experience would be much appreciated.
