# Arduino Uno Max Amp Input

Hi everyone, I'm still pretty new to Arduino so I might be asking stupid questions but any answers would be really great.

I have an Arduino Uno that I want to power using 12 volts 1.5 amps. Is this possible? I thought that the Uno could handle 6 - 20 volts max, but I don't know what the max amperage is.

Any answers would help a lot. :)

You only need to be sure that the power supply can provide at least the amount of amps the Uno (and whatever else you might be powering off the supply requires). A power supply rating of anything over that is no problem.

Compare an Arduino with a light bulb. It draws current. If the light bulb (or all light bulbs together) draws too much current, you will blow the fuse in your house. In a similar way, if the Arduino draws more current than the power supply can deliver, it will not work (power supply drops voltage or shuts down).

Be aware that the voltage regulator in the Arduino needs to dissipate the heat caused by the voltage drop (12V minus 5V equals 7V) and the required current (e.g. 100 mA total). It will shut down when it gets too hot.

If you're only powering the Arduino, you will be OK. If you're also powering other 5V devices from the 5V output pin of the Arduino, it might or might not be OK; you will have to sum all the currents of the connected devices.

Thanks for the answers sterretje and pert!

So I can apply that much amperage and it won't burn the board.

Thanks so much! :)

You don't supply amperage to the arduino. The arduino draws amperage from the power supply. For arguments sake, let's say the arduino needs 0.1A to work. That's all it will draw. The extra 1.4 A in the power supply is avaialble for other devices. If you connect a second Arduino it too will draw 0.1 A. The total draw from the power supply is now 0.2 A and the power supply still has 1.3A available for other devices.

Makes sense?

Oh! That totally makes sense! Thanks DBMcDonald! I'm still really new to all this electrical stuff and I might just miss some stupid simple points. But thanks for the answer! That clears it up a lot! :)

Wait, so how much amperage does an Arduino Uno need? Like how much extra do I still have for other parts or devices.

With a 12V input, you might be able to draw 300-400mA before the 800mA max 5V regulator overheats and shuts down. If you need a lot current, get a 5V wallwart and power the Arduino and the other loads in parallel from it.

The regulator will smoke/fail with 20V, don't try that. Look at datasheet, page 3.

https://www.onsemi.com/pub/Collateral/NCP1117-D.PDF

Only the 12V output device is recommended to be run at 20V.