Calculate Resistor Value
How to Calculate Resistor Value For LED 5V Arduino – In practice, LEDs cannot be separated from the design of electronic equipment. almost all electronic devices use LEDs. But how do we connect this LED to a voltage source safely?
From that, we must know the specifications of the LED, both the current and the voltage used. In this article we will study only general LED specifications. For more details, you can refer to the datasheet of the LED manufacturer you are using.
Generally, LEDs have a forward current specification of 20mA and a forward voltage of at least 1.8 volts and a maximum of 2.2 volts.
If the available source voltage is 5 volts and we connect it to the LED, the LED will burn out. Why is that? because the current flowing through the terminal or semiconductor of the LED is at the limit of the LED itself.
The solution is we have to use a resistor to limit the current flowing into the LED.
To get the exact value to use for the LED, we will use the following formula:
R = V / I
= Vsourve – Vled / Iled
= 5V – 2.2V / 20mA
= 139.99999999999997 Ohm
We get the result from the calculation that the minimum used resistor is 139.99 ~ 140 Ohm. But in the market “to my knowledge” there are no resistors with a resistance of 140 Ohms, which comes close to that value is 150 Ohms.
If we use a resistor with a resistance of 150 Ohm, the LED is still safe, but the light produced is very bright and will shorten the life of the LED.
Generally, the resistance that most people use in limiting the electric current of an LED is in the range of 220 or 330 Ohms. The greater the resistance value used, the dimmer the LED will be.
In the picture above is an example of using resistors on LEDs. Where the LED is connected to one of the Arduino Uno’s Digital pins which outputs HIGH logic or 5 Volt voltage.
By using a resistor as a limiting current to the LED, the LED will be safe from burning and will extend the life of the LED itself.