1. What is LED Current-Limiting Resistor?

A current-limiting resistor is essential for protecting LEDs from excessive current that can damage or destroy them. It ensures the LED operates within its specified current range by dropping the excess voltage from the power supply.

2. How Does the Calculator Work?

The calculator uses the LED resistor formula:

Where:

• \( R \) — Resistor value in ohms (Ω)
• \( V_{supply} \) — Power supply voltage in volts (V)
• \( V_{led} \) — LED forward voltage in volts (V)
• \( I_{led} \) — LED forward current in amperes (A)

Explanation: The formula calculates the resistance needed to limit current through the LED by dropping the voltage difference between supply and LED forward voltage.

3. Importance of Current Limiting

Details: LEDs are current-driven devices that require precise current control. Without proper current limiting, LEDs can overheat, experience reduced lifespan, or fail immediately due to thermal runaway.

4. Using the Calculator

Tips: Enter supply voltage in volts, LED forward voltage in volts, and LED forward current in amperes. Ensure supply voltage is greater than LED forward voltage for proper operation.

5. Frequently Asked Questions (FAQ)

Q1: What are typical LED forward voltages?
A: Red LEDs: 1.8-2.2V, Green/Yellow: 2.0-2.4V, Blue/White: 3.0-3.6V. Check manufacturer datasheet for exact values.

Q2: What are common LED currents?
A: Standard LEDs: 20mA (0.02A), High-brightness LEDs: 30-150mA, Power LEDs: 350mA-1A or more.

Q3: What if my calculated resistor isn't a standard value?
A: Use the next higher standard resistor value to ensure current doesn't exceed the LED's rating.

Q4: Can I connect multiple LEDs?
A: For series connection, sum LED voltages; for parallel, calculate separate resistors for each LED branch.

Q5: What about resistor power rating?
A: Calculate power: P = I² × R. Choose resistor with power rating at least 1.5 times calculated value for safety margin.