We need to inform a user when the battery is going to die .
Our pcb has a 3.7V battery , that goes into a regulator (LD6806) of 3.6V to drive the atmega328p.
Our board mostly in sleep mode, and consume only 50-100uA while sleep .
We need to measure current only when the MCU is awake and to detect if its about to end.
Using 2 resistors to divide the voltage and input that to the ADC sounds great, but the problem with it, is that it has a hell of a leakage (current ).
We cant afford putting 2 of 10k resistors .
i was thinking of putting 2- 100k resistors, to divided the voltage and into the ADC, but i have heard the MCU cant have this resistors in the input ? why ?
I have read here about software only solution that measures the atmega's own voltage . but in our case its voltage is from regulator . can we use that to determine when battery going to die ?