Strange question I know but is there any reason I can’t run a 3.3V Arduino Pro Mini using a regulated 5V supply and bypassing the onboard 3.3V regulator? Best I can tell it will just run at 8MHz but work fine at 5V?
Have a strange situation where it will run off of a 3.7 battery sleeping (very power sippy) until it needs to do sampling, it which case it will fire up a regulated 5V supply do it’s measurements, then power down the sensors, regulated power supply and go back to sleep until time to do it all over again. The sensors all require regulated 5V to work.
Bypassing the in-built 3.3V regulator will not be possible. Arduino Pro Mini is designed to run at 3.3V. The input voltage can be 3.3V to 12V. But the in-built regulator will maintain always 3.3V. If you give direct 5V bypassing the regulator, the board is most likely to damage.
The only thing that really defines a “3.3V Pro Mini” is the 3.3V regulator.
If you remove the regulator, the ATmega328 on the Pro Mini will work fine on any voltage from about 2.0 to 5V, albeit at the default 8 MHz. It is easy to remove, just swipe it off with the tip of a solder pencil.
The modified Pro Mini will work well with 2x or 3x AA battery packs, although sensors are usually not so forgiving.
The 3.3 volt board will run just fine on 5 volts but there is a 5 volt 16MHz board that would work just as well for you.
Thanks for the info, planning on running on a lipo 3.7 battery pack, using raw output of 3.7V while in low power more, then wake up, power up a 5V boost regulator, feed that into the Arduino via steering diodes so that the 5V won’t feed back into the 3.7 battery, and also feed the sensors, LORA radio and AREF pin, then sample the A0 line with it being set to EXTERNAL, send the data via LORA, then power off the regulator turning off everything except the Arduino at 3.7V, and drop back into deep sleep.
That will avoid running the regulator or sensors/radio with any power until sample time of once every 3 to 4 hours.
Again thanks