Mixup of 3 and 5v input

Hardware Nano Family Nano ESP32
1

I probably know the answer already but I wanted to confirm with the experts.

I have a Nano ESP32 and in my prototyping I moved my power wire from VBUS to the 3V pin. Everything was fine because I was powering via USB and the 3V was an output only to my sensors and display. Later I redesigned and went back to powering with a 5V battery but forgot to move the power wire off of the 3V pin.

Bottom line: I powered the Nano with 5V on the 3V pin for some time. Now it will not power up via the USB or with voltage on the VIN pin. It will still power via 5V on the 3V pin but not with 3V on the 3V pin. I assume the internal power converter is probably fried?

Also since this isn't really supposed to work like this, is the rest of the board tolerant to 5V on the 3.3V rail?

Lastly, I also found it interesting that I could power the board externally and then plug in the USB and successfully program it. So it's not a complete loss, just a little extra awkward since I have to keep the external power pack with it always.

Any thoughts on the damage done? Or perhaps a fix other than an external power supply?

Thanks

Brian

2

Well, if that's all, consider yourself lucky. Applying 5V to the 3V3 pin also powers the ESP32 with 5V, which it is very much not designed for.

How extensive the damage is, I can't really tell. Something's fried, that much seems clear. Maybe it's just the step-down converter. Maybe some stuff in/around the ESP32/NORA module is also dead. Time will tell, most likely.

This may be a good moment to purchase a spare, though.

3

Use it for testing, but don’t expect it to last. The damage has already been done, though not all failures happen immediately—some will take time to manifest.