Hello, I was previously using as a power source a 3.7v battery directly to the sleeping Atmega.
The thing is that I'd like to run the whole system at 5v, but not all the time (so that I don't waste energy running the 5v booster for the Atmega just to be sleeping). This is what I have in mind:
Connect the 3.7v battery to the Atmega, the Atmega will be on sleep mode until certain time. When that certain time arrives, I'd like the chip turn on a 5v booster module like the one from a cheap power bank as an example, to power itself from the same line as the 3.7v.
How can I approach this?
A MOSFET and a couple of diodes? Note that it will only be on for less than a minute, if that matters.
If the 3.7 V batterie is connected to the Atmega, you cannot connect it to the 5v booster and then to the atmega again, you would be connecting it twice. Why do you need 5V? Maybe you can work with 3.3 v devices, you wouldnt need a booster.
mart256:
If the 3.7 V batterie is connected to the Atmega, you cannot connect it to the 5v booster and then to the atmega again, you would be connecting it twice. Why do you need 5V? Maybe you can work with 3.3 v devices, you wouldnt need a booster.
DrDiettrich:
I wouldn't expect much additional saving from reducing the supply voltage in sleep mode. Instead I'd turn off all external power consuming circuitry.
Should I use something like a subsystem? I'm thinking a attiny controlling the atmega power?
I don't see why an Arduino can't control it's own supply.
Try a tiny Pololu 5volt boost converter.
Let the Arduino control the enable input (has to be pulled low with a diode or small mosfet).
Put a schottky diode across in and out, so the Arduino still gets battery supply when the boost converter is off.
You might have to read up about boost converter idle/sleep current.
Leo..