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I believe I can supply the Arduino with power in three different ways:

  • Use USB. The design trusts the 5V to be regulated, and does not regulate it in any way.
  • Use a regulated power source, trusted to be 5V, and connect it to GND and 5V.
  • Connect an unregulated power source, eg a battery, to GND and VIN. This should be above 6.2V (since the dropout voltage is 1.2V) and preferably between 9V and 12V. There is a built-in regulator that will supply the Arduino with exactly 5V.

But can I use any of those pins to power other components. E.g. if the Arduino is powered with USB, can I use the 5V pin to power a diode? I thought I could, but the voltage is 4.70V, while the USB is 5.07V. The VIN is 4.26V btw.

Are the 5V and VIN only for powering the Arduino?

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  • It's an Arduino Nano, so no barrel jack.
    – Mads Skjern
    Commented Oct 4, 2014 at 20:41
  • 1
    where and when were you getting those voltages? It could be a drop from measuring with and without other current flowing from USB (if you measured initially without the arduino). There should be a small drop as the USB input power does go across a fuse (F1 on schematic) and a mosfet (T1) before reaching the 5v pin.
    – BrettFolkins
    Commented Oct 4, 2014 at 21:03
  • 1
    I put the Nano in a breadboard. And I measure the voltages with a multimeter, which I put in the breadboard right next to the pins from the Arduino. I understand that there can be a voltage drop when there is a load, ie when there is a current. But there is no other load in my setup, than what is inside the Arduino itself.
    – Mads Skjern
    Commented Oct 4, 2014 at 21:39
  • 1
    I measure the 5.07V, by putting the multimeter on the points where the USB connector is soldered to the Arduino.
    – Mads Skjern
    Commented Oct 4, 2014 at 21:41
  • 4
    There is Feeding power to Arduino: the ultimate guide
    – jediz
    Commented Jan 4, 2017 at 9:09

4 Answers 4

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37

No. You can draw power from the 5v and VIN pins on the arduino. VIN is the completely unaltered input power before the regulator (it will be useless if regulated 5v is supplied directly). Outputting power is what the 5v pin is intended to be used for, not as a power input.

From the arduino website:

5V. This pin outputs a regulated 5V from the regulator on the board. The board can be supplied with power either from the DC power jack (7 - 12V), the USB connector (5V), or the VIN pin of the board (7-12V). Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board. We don't advise it.

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3
  • 13
    Yet, provided that you do not exceed 5.5 volts on the +5v pin, you can absolutely use it to supply the arduino. You bear the responsibility of ensuring that you do not exceed 6v though.
    – David Hoelzer
    Commented Nov 26, 2015 at 14:34
  • 1
    I am still wondering how the USB power fits into this. Does the USB power bypass the regulator? I think it must otherwise there is too much of a voltage drop. So is powering the Arduino through the +5V pin the same as powering by USB? And does powering it through the +5V pin still also give the +3.3V?
    – tcurdt
    Commented Dec 19, 2020 at 20:31
  • you can input power into an arduino, up to 20 volt, via vin pin.
    – clockw0rk
    Commented Sep 20, 2021 at 19:36
6

They can also be used to draw power from the barrel jack (Vin) or from USB or the on-board regulator (5V). The schematic of the board shows all exact power paths.

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3
  • Ok, but then why does the 5V and VIN pins have lower voltages then? And wouldn't that be a problem for many applications? I imagine that if I used a LCD display rated at 5V, it could (potentially) be a problem that it only gets 4.70 or 4.26V?
    – Mads Skjern
    Commented Oct 4, 2014 at 20:46
  • Btw: I am not an electrical engineer, and I am not able to understand the schematics. Maybe one day :)
    – Mads Skjern
    Commented Oct 4, 2014 at 20:47
  • 2
    It gets a lower voltage because the traces on the board have non-zero resistance, which results in a voltage drop. Check the datasheets of all components to see what voltage range they can accept, but 4.70V should be fine for 99% of all 5V electronics.
    – Ignacio Vazquez-Abrams
    Commented Oct 4, 2014 at 20:57
5

5V pin can be used to power up shields like Bluetooth, RFID, ultrasonic sensors etc..

vin pin is used to power up the Arduino. For example, when using shields such as L298 motor shield which is providing 5V output while operating from 12V.

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0

The MBR0520 Schotky Power Rectifier (Surface Mount Schottky Power Rectifier) is connected in the Series path of 5v pin present on Nano which can handle maximum of 12V reverse voltage and according to datasheet 20v typical valur thus we can power ON arduino NANO using 5v pin also provided you supply proper 5v through any type of DC-DC Converter to it. https://www.onsemi.com/pub/Collateral/MBR0520LT1-D.PDF http://malylubo.sk/wp-content/uploads/2013/01/Arduino_Nano_Schematic-1024x676.png

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