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Topic: Why arduino can fry? (Read 2 times) previous topic - next topic

pedroply

Hi,

Today a read that my arduino uno can fry by conecting a DC motor direcly into one of the i/o pins.
Anyway my question is why can it fry my arduino?

This may look a ridiculous question but I hope you can answer to it.

thanks.

AWOL

Becasue the DC motor will have a very low resistance, and the AVR will exceed its 40mA maximum rating trying to drive it.
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

pedroply

Thanks for the reply and for moving my topic.

What is the AVR?

Sorry for being so anoying.

AWOL

It's the microcontroller on your Arduino.
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

dhenry

Quote
why can it fry my arduino?


Low (dc) resistance isn't the issue: you can actually short your avr's pins without damaging them.

Motors are inductors who will try the best to sustain its status quote. If the current going through it is cut off, it will create a significant voltage trying to sustain that current. That voltage is higher if the cut-off is quicker.

So w hen your io pins turn off fast, that huge voltage is applied to the pin -> causing it to go to the avr heaven.

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