About powering documentation of 33 IOT

What is minimum power supply voltage for this board. Is there a way to use external 3.3V voltage as supply, or feed 5V to to the board.
I ask because I bought a low quiescent current 5V voltage source for the board, but it looks like I can't use it. I planned to use this board with a relatively small lead acid battery and there is practically no solar power here to charge it now. It is cloudy and/or rainy here, this time of the year.

The MPM3610 power converter used on the board has a minimum input voltage of 4.5V. So, 5V on the Vin pin should be fine.

You could try to power the board through the 3.3V pin if you want to use your own regulator. Unfortunately, there is no bridge to disconnect the power converter from the 3.3V (like on the Nano 33 BLE), so there might be some side effects e.g. some additional leakage current through the MPM3610.

Good to know. Thanks.
Board specs don’t talk about minimum input voltage. Could someone update the info?