Excess voltage applied to 5v pin on UNO

On my last project, I accidentally applied my red voltage wire from my 12v battery pack to the 5v pin instead of the VIN pin. Now, I am not able to upload new code to my board. Does anyone know what I may have fried on my board and if I should be able to replace part(s) to get it working properly again? If it could be any one of several parts that fried, how do I test them?

Remove the processor, try the loopback test. If that passes (unlikely, as 12V almost certainly fried the USB/Serial chip), then try simple blink sketch upload, perhaps re-bootload the uC.
Extremely likely that you blew both chips tho, as they have Absolute Max of 5V on Vcc pins, and you applied 12V. Does either one feel warm/hot to the touch?
You reverse drive the 5V regulator too, if that feels hot now that is probably dead too.

I accidentally applied my red voltage wire from my 12v battery pack to the 5v pin instead of the VIN pin.

That put in jeopardy every component on the 5V rail - which is nearly every component on the board.
Resign yourself to procuring purchasing a replacement.

Regrettably, the effort to find & repair the damaged component(s) is likely too great. Plus, even a working component could be marginal.

I vote replace.


I agree with mrburnette.
Sometimes a board still works after a voltage up to 8V. But 12V destroyes it.

It's dead. Time to move on.

You might find one or two components left working :slight_smile:

RIP uno.

You're not alone! I've done that twice! Fortunately I can pick up arduino clones locally for about $20 a pop. So I have a small supply should I do it again.

There is one Arduino clone that's supposed to be hardened to deal with stuff like this, which could be could for the building and testing phase. It's called the Ruggeduino. It's about twice the cost of the normal arduino clone. But still could be useful!

Yes, the ruggeduino would (or should) have survived this mistreatment:

The 5V output connector pin is current-limit protected by the thermal shutdown feature of the on-board 5V regulator. In addition, this pin is protected against applied overvoltage. Any voltage at this pin above 5.5V (typical) will disconnect the pin from the rest of the Ruggeduino circuitry, preventing this damaging voltage from reaching the other components.

Applied voltages of up to 24V are blocked.

Touch wood I have never done this to an Arduino yet, however my first Raspberry Pi did it to itself by applying 5V to the 3.3V power pin due to the pins being sited next to each other and there being no protection between them...