Introduction

This calculator assists in finding the appropriate values for current-limiting resistors when connecting LEDs in series. To operate the calculator, just input the supply voltage, the forward voltage and forward current of the LEDs in the series. The calculator will then determine the necessary resistance value and power to ensure the LEDs operate at the specified current.

LED Series Resistor Calculator Formula =

If is the forward current amperes measured in mA.

Where,

Vs is supply voltage

Vf is forward voltage

If is forward current

LED Series Resistor Diagram

LED Voltage and Current

Light Emitting Diodes (LEDs) are specialized diodes designed to emit light when an electric current passes through them in their forward-biased state. These components come in a variety of colors including red, green, yellow, blue, orange, white, and even infrared, which is not visible to the naked eye but can be used for various applications such as remote controls.

A key parameter for any LED is its forward voltage drop (Vf), which is the voltage required across the LED to turn it on and allow current to flow through it. In the case of standard low-power LEDs, this forward voltage typically ranges from 1.2V to 3.6V, corresponding to operating currents of about 10mA to 30mA. The specific value of Vf can vary based on several factors, including the type of semiconductor material used in the LED, the intended color of light emission, manufacturing tolerances, and the amount of forward current passing through the device.

Importance of LED Series Resistor

Using LED series resistor is to cap the current and ensure that the LED receives the correct amount of current for operation. To safeguard the LED from excessive current, a series resistor is used to restrict the flow. This resistor uses Ohm's law to regulate the current, making sure the LED gets the right amount without surpassing its maximum safe current. Current control also helps in maintaining the LED's brightness and performance consistency.

FAQ

Do I need a resistor for LEDs in series?

If the flow of current through LEDs is not restricted, they can suffer damage and potentially fail catastrophically. To prevent this, a common solution is to incorporate a resistor of the correct value in series with the LED. In scenarios involving high-power LEDs, you might also encounter current-limiting power supplies or integrated circuits (ICs) designed to restrict the current.

What size resistor do I need for my LED?

An LED in a circuit without a current-limiting resistor can quickly surpass its safe operating current, leading to burnout within a short period. For the majority of projects, a resistor with a power rating of 1/8W or 1/4W should suffice. However, for applications involving extended use or higher power demands, it's advisable to verify the resistor's suitability to ensure long-term reliability and safety.