Just looking for a second opinion on my circuit below. Wired up everything works great, but last night as i was unplugging the FTDI programmer something seemed to have happend, and the mini was bricked.

I'm not sure if it has to do with my wiring below, or if it was me unplugging the cable in a haphazard manner.

What I'm attempting to do is run my arduino from 12v wall supply, but also drive an LED strip with it. I'm just unsure if this is the best way to go about it, any advice is welcome.

Thanks Justin

example layout

  • Is that just a Fritzing artifact, or is that power supply in backwards? It looks to me like the center pin is going to ground. See have I bricked my Arduino for possible tests you can do to confirm if you really bricked it.
    – Nick Gammon
    Aug 24, 2015 at 22:23
  • Ya, that's just fritzing showing it backwards.
    – JW2
    Aug 24, 2015 at 22:27
  • I would try (amongst other things) removing it from the breadboard, and trying to program it just with the FTDI cable.
    – Nick Gammon
    Aug 24, 2015 at 22:29
  • Oh yea, sorry I didn't completely respond. The arduino is definitely bricked. I just wanted to make sure the 12v led circuit wasn't wired incorrectly and overheating caused the brick. Should there be a capacitor somewhere? It seemed like when I unplugged the ftdi it blew something.
    – JW2
    Aug 24, 2015 at 22:30
  • A little off topic- but what program did you use to make the above diagram?
    – Vinterwoo
    Jun 28, 2016 at 19:23

1 Answer 1


According to the schematics, the Pro Mini uses the MIC5205, which is a linear regulator. Using it directly with 12V is not a very good idea, in terms of power efficiency, as it will dissipate 35mW vs 25mW provided to the ATMega board.

From this perspective, I'd recommend a step-down converter for powering the Arduino.

However it will not cause any damage, at least at room temperature, as the power dissipation is well within operating margins, see calculation at page 8 of the MIC datasheet.

Edit: detailed pros and cons, power wise.

  • Arduino says input voltage can range up to 12V: arduino.cc/en/Main/ArduinoBoardProMini Is my circuit correct, or is this damaging to the Arduino?
    – JW2
    Aug 24, 2015 at 17:52
  • I'm trying to keep my circuit as compact as possible, which is the reasoning for wiring 12v into RAW, allowing arduino to step the voltage down.
    – JW2
    Aug 24, 2015 at 17:55
  • 1
    not a very good idea; please explain. In this circuit it's probably just fine, as an ATMega328 by itself only uses around 5mA, so the voltage regulator would dissipate only 35mW of heat.
    – Gerben
    Aug 24, 2015 at 17:59
  • Are you telling me it's not a very good idea, or are you asking Igor Stoppa to explain further?
    – JW2
    Aug 24, 2015 at 18:10
  • It dissipates 35mW vs 25mW provided to the Arduino. Not very efficient, power-wise. The preference for using the absolute minimum set of components was not part of the original question. Aug 24, 2015 at 18:23

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