I am quite new to arduino .Something in the specification list makes me confused :

enter image description here

I am confused about the following :

  1. Input Voltage(recommended)7-12V
  2. Input Voltage (limits) 6-20V
  3. Operating Voltage : 5V

Is Operating Voltage is the voltage that is used to power up the board ? If So,What does Input Voltage(recommended) and (limits) refer to? Are they regular analog input voltages?

Any Help regarding "Operating Voltage" and "Input Voltage" is highly appreciated !


2 Answers 2


The MCU itself and associated circuitry runs at 5V. In order to provide a proper power supply for this, the Arduino has a voltage regulator on-board. This regulator should be supplied between 7V and 12V from an external source. Putting less than 6V or more than 20V into the board can damage it permanently.


The 5 volts is the operating voltage. The Atmega328 (the micro-controller on your Arduino) is capable of operating on voltages between 1.8 and 5.5 volts. However it only runs stable at 16MHz with at least ~4 volts. Running at 5 volts increases compatibility with other 5 volt devices with smaller margins.

The input voltage is the voltage you supply to the board into a linear voltage regulator. That regulator is a component that acts as a variable resistor is such a way that it always outputs 5 volt. However, because of the way it works, it always drops the voltage at least 1.25 volts. Than there is also a diode that drops the voltage a fixed ~0.7 volts.

So the input voltage is always reduced at least ~2 volts. This results in a recommended minimum input voltage of 5+2=7 volts, but 6 volts will turn it on too, but at a reduced operating voltage. If you bypass the regulator you should only supply a regulated operating voltage of 5 volts. This is what happens when you use the USB port's 5 volt.

The voltage regulator turns the excess voltage into heat on a very small component. So while it may be capable of regulating 20 volts into 5 volts, the 15 volts difference turns three times the energy the rest of the board uses into heat. Without a heat shield it will heat up until it malfunctions. With a 12 volts input there is only a 7 volt difference (less than half of before) and it is still capable of sufficiently dissipating the heat to the air.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.