ESP32 Development Board with 3.3v in and USB

[pmckeon]

I have an ESP32 Development Board (or at least a clone of one) that I was intending to power via a 3.7v lithium cell -> charge controller -> 3.3v voltage regulator on the 3.3v pin

Is this going to upset or damage the existing 3.3v regulator onboard? What if I had both the USB and external 3.3v regulator connected at the same time (which programming)? It seems unlike the 5v input there is not a diode protecting the voltage regulator.

If that's going to be a problem I'll have to switch out the 3.3v regulator in my design for a 5v, I just figured the 3.3v regulator would be more efficient.

[bobolink]

I read this:
“Above options are mutually exclusive, i.e. the power supply may be provided using only one of the above options. Attempt to power the board using more than one connection at a time may damage the board and/or the power supply source.”
From:
https://docs.espressif.com/projects/esp ... vkitc.html
You should check the documents for the board you are using. Or do the analysis yourself (a complex dynamic transient analysis).