Skip to main content
Added further info on using 5V pin
Source Link
jfpoilpret
  • 9.1k
  • 7
  • 37
  • 54

Short answer: NO. It would fry your Arduino.

Long answer:

The current of Arduino pins is very limited (40mA max on UNO).

If you need to draw 1A, then you need a transistor between the Arduino pin and your device.

In such case, what you would normally do is:

  • connect any Arduino logical pin to the transistor base (through a resistor),
  • plug your device between a 5V supply (capable of 1A current providing) and the transistor collector,
  • connect the transistor emitter to the Arduino GND pin (and connect that pin also to the 5V-1A supply)

Note that you don't need to use an analog pin for that, a logical pin is enough if you just want to switch the device on or off.

Now notice that I specified a 5V 1A supply, that should normally be distinct from the 5V pin of the Arduino.

So the next question is: can you draw 1A out of the Arduino 5V pin?

The Arduino UNO page does not specify the current limitation on that pin. However it mentions the following:

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).

So the max current on this pin depends on 2 factors:

  • what is the power supply for the board: it is either USB, or an external power supply, which can be connected to the power plug or to the Vin pin.
  • the specs of the 5V regulator voltage on the Arduino board

If you use USB as power supply, then you are limited to 500mA as stated in the Arduino UNO page:

The Arduino Uno has a resettable polyfuse that protects your computer's USB ports from shorts and overcurrent. Although most computers provide their own internal protection, the fuse provides an extra layer of protection. If more than 500 mA is applied to the USB port, the fuse will automatically break the connection until the short or overload is removed.

If you use an external power supply that provides at least 1A, then we have to find out the max current by ourselves.

If we take a look at Arduino UNO schematics, then we see that this regulator is referenced as "NCP1117ST50T3G" (this is "U1" on the top-right corner).

The spec sheet for this regulator mentions that it can supply 1.0A.

So in theory, that should work, however, you also have to consider that this regulator also supplies current to the Arduino borard itself and all its pins.

If you love your Arduino and don't want to fry it, you should probably stay away from using its 5V pin for your purposes.

Now if you're open to experiment, you may try it :-)

Short answer: NO. It would fry your Arduino.

Long answer:

The current of Arduino pins is very limited (40mA max on UNO).

If you need to draw 1A, then you need a transistor between the Arduino pin and your device.

Short answer: NO. It would fry your Arduino.

Long answer:

The current of Arduino pins is very limited (40mA max on UNO).

If you need to draw 1A, then you need a transistor between the Arduino pin and your device.

In such case, what you would normally do is:

  • connect any Arduino logical pin to the transistor base (through a resistor),
  • plug your device between a 5V supply (capable of 1A current providing) and the transistor collector,
  • connect the transistor emitter to the Arduino GND pin (and connect that pin also to the 5V-1A supply)

Note that you don't need to use an analog pin for that, a logical pin is enough if you just want to switch the device on or off.

Now notice that I specified a 5V 1A supply, that should normally be distinct from the 5V pin of the Arduino.

So the next question is: can you draw 1A out of the Arduino 5V pin?

The Arduino UNO page does not specify the current limitation on that pin. However it mentions the following:

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).

So the max current on this pin depends on 2 factors:

  • what is the power supply for the board: it is either USB, or an external power supply, which can be connected to the power plug or to the Vin pin.
  • the specs of the 5V regulator voltage on the Arduino board

If you use USB as power supply, then you are limited to 500mA as stated in the Arduino UNO page:

The Arduino Uno has a resettable polyfuse that protects your computer's USB ports from shorts and overcurrent. Although most computers provide their own internal protection, the fuse provides an extra layer of protection. If more than 500 mA is applied to the USB port, the fuse will automatically break the connection until the short or overload is removed.

If you use an external power supply that provides at least 1A, then we have to find out the max current by ourselves.

If we take a look at Arduino UNO schematics, then we see that this regulator is referenced as "NCP1117ST50T3G" (this is "U1" on the top-right corner).

The spec sheet for this regulator mentions that it can supply 1.0A.

So in theory, that should work, however, you also have to consider that this regulator also supplies current to the Arduino borard itself and all its pins.

If you love your Arduino and don't want to fry it, you should probably stay away from using its 5V pin for your purposes.

Now if you're open to experiment, you may try it :-)

Source Link
jfpoilpret
  • 9.1k
  • 7
  • 37
  • 54

Short answer: NO. It would fry your Arduino.

Long answer:

The current of Arduino pins is very limited (40mA max on UNO).

If you need to draw 1A, then you need a transistor between the Arduino pin and your device.