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Topic: Protection of reverse voltage of an arduino (Read 166 times) previous topic - next topic


Have any others used a diode like the MC78M05CDTG to protect an Arduino from reverse voltage?

I am creating a board that has a 12v 5 amp power supply to control various LEDs.  I am going to place a voltage regulator (7805) in line to the arduino to bring it down to 5v.  I want to protect the Arduino from all the other power connections and in case I'm an idoit.

Am I over thinking this setup?


Have any others used a diode like the MC78M05CDTG
That's not a diode...

You can use a series diode but you'll get a voltage drop (about 0.7V) so the diode should be on the 12V side of the regulator.   Or, a Schottky diode will only drop about 0.3V which you might be able to live with on the 5V side of the regulator.

You can use a reverse diode to ground, which will "short out" any negative voltage.   In that circuit  there should be a fuse so the fuse blows before you fry the diode & power supply.

and in case I'm an idoit.
Use a polarized connector and check everything with a multimeter (or LED voltage tester, etc.) before connecting the 1st time.    Or, go-ahead and try a series diode on the 5V side until everything is working OK.   It should "work OK" with the slight voltage drop.


I know I can plumb 12v right to the Arduino.  But is it horrible to run it that high?  I'd like to chill it out a bit before it gets to the arduino.


Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

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