Electronic – arduino – Maximum Current Draw on Vin Pin


I don't want to damage the pins on my Arduino Uno, and I'm especially cautious of drawing too much current. I'm experimenting with a small servo motor (similar to this one), and have connected the power line to the Vin pin on my Arduino. (I'm powering the Arduino via a 9v battery connected to the DC jack).

I know the current limits for the digital ports (which are covered in this question), but I haven't been able to find any current draw limit for the Vin pin. Is there a limit determined by the Arduino hardware?

Best Answer

You can look at the schematic for the Uno to see for yourself.

Looking at that, you can identify the power pins (top right) and see that the Vin pin comes straight from Vin, without going through the MCU or any other chip. Then, if you look towards the top you can see that the only thing separating Vin from the power supply is a single diode.

In short, there is nothing on the Uno that would limit the current draw of Vin. The only consideration is that you don't draw so much current that the voltage drops. This could cause the Arduino to reset (which is probably undesirable). So just limit your current to what your power supply can handle.

Edit: As stated in comments, the diode and trace width are other limiting factors. The diode is rated at 1 amp and the board traces can't handle much above 2 amp.