How much Current can Arduino Supply

Arduino boards can control multiple electronic circuits. They can be a source of current for different circuits. Simple circuits like lighting the LED or micro motors can be powered up using Arduino. But every source has limitations similarly Arduino has some current limit; we cannot draw current beyond those limits. Here in this article, we will discuss how much current we can draw from the Arduino without burning out the board:

Current sources in Arduino

Arduino have different current limits depending upon from which pin current is drawn. Before going further first we need to understand all the current sources available in Arduino through which we can draw Current. Arduino can be powered up using these sources:

• USB Port
• DC Barrel Jack
• Vin Pin

All these sources have different input voltage capacity and supply current according to input provided at their terminal. Now we will discuss how much maximum current we can draw using these inputs.

USB Port

Simplest and easiest way of powering an Arduino is using a USB cable. It can take power from any source which supports USB ports like wall socket, computer USB ports or power banks.

Current Limit of USB Port
When the Arduino is powered using a USB port, the current is limited to 500mA due to the USB interface. This power is shared among the components on the Arduino board at the end, available power is somewhat less. Remember 500mA is the maximum limit it is always recommended to not draw current more than 400mA.

Overcurrent Protection for USB
For overcurrent protection a Resettable Polyfuse is used that protects from any kind of shorts and overcurrent on Arduino. If current more that 500mA is being drawn using USB then it will trigger the polyfuse and cut off the connection to USB Power. Once the overcurrent is removed it will reset to its original condition after some time, which depends upon how much current limit Arduino has exceeded as it is a Thermal fuse.

DC Barrel Jack
DC barrel jacks are specified for using external power supplies for Arduino in case more power is required for circuit. Voltage from the barrel jack is connected to the on-board 5V voltage regulator and then output of this 5V regulator is connected to 3.3V regulator.

Current Limits of DC Barrel Jack
Some Arduino boards like UNO have an on-board barrel jack. Using it we can connect external power supply, power drawn using barrel jack is first regulated. There are two types of regulators on Arduino boards.

• 5V Regulator
• 3.3V Regulator

5V Regulator
Unlike USB ports, Barrel jacks are not limited to 500mA; by connecting an external supply we can draw a maximum current of up to 1A. Current beyond this limit is not possible due to an on board 5V regulator, whose maximum rating is 1 Ampere. However, we are thermally limited here as you draw more current, the regulator will heat up resulting in less output current, this is called Thermal limiting.

3.3V Regulator
The 3.3V regulator can supply current up to 150mA. Any power drawn using a 3.3V pin has to go through a 5V regulator first. The 3.3V voltage regulator specification are:

Vin Pin

Vin pin on Arduino boards works dual way; they can act as power source when external power supply is not connected at barrel jack. Also, it can be used as a voltage output pin.

Current Limit of Vin
Current limit of Vin pin is same as the DC barrel jack as it is directly connected to the onboard voltage regulator, as discussed earlier 5V voltage regulator has a maximum current capacity of 1 Ampere.

Note: Vin pin does not have any reverse polarity protection diode, so be careful while giving power through Vin.

Current limit for I/O Pin

Maximum current limit for any I/O pins is 40mA, this is the maximum current after which ATmega microcontroller can no longer handle. Total current drawn from all I/O pins altogether is 200mA max.

If you draw more current than 40mA from an I/O pin, it will damage the I/O pin as there is no fuse on these pins.

Conclusion

Arduino can control multiple devices, motors, and circuits. Amount of current drawn from the Arduino depends upon what components are attached with the circuit. In this tutorial we have covered the current limits of Arduino boards. Controlling current in a safe limit is a great skill for safely running your Arduino with powerful devices like motors. Knowing all this information will help in circuit design.