1. What is a Current Limiting Resistor for LED?

Definition: This calculator determines the appropriate resistor value needed to safely operate an LED with a given power supply.

Purpose: It helps electronics enthusiasts and engineers prevent LED burnout by limiting current flow through the LED.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( R \) — Resistor value (ohms)
• \( V_{supply} \) — Power supply voltage (volts)
• \( V_{led} \) — LED voltage drop (volts)
• \( I_{led} \) — Desired LED current (amps)

Explanation: The resistor value is calculated by subtracting the LED's forward voltage from the supply voltage, then dividing by the desired current.

3. Importance of Current Limiting Resistor

Details: LEDs are current-driven devices that can be damaged by excessive current. A proper resistor ensures the LED operates within its specified current range.

4. Using the Calculator

Tips: Enter the supply voltage, LED voltage drop (typically 1.8-3.3V depending on color), and desired LED current (usually 10-30mA). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What happens if I don't use a resistor?
A: Without a resistor, the LED may draw excessive current, leading to immediate burnout or reduced lifespan.

Q2: How do I know the LED's voltage drop?
A: Check the LED's datasheet. Common values: red (1.8-2.2V), green (2.0-3.3V), blue/white (3.0-3.6V).

Q3: What current should I use for my LED?
A: Standard LEDs typically use 20mA, but check your specific LED's maximum current rating.

Q4: What if my calculated resistor isn't a standard value?
A: Use the next higher standard resistor value to ensure safe current levels.

Q5: How do I calculate resistor power rating?
A: Power = (V_supply - V_led) × I_led. Choose a resistor with at least double this power rating.