1. What is an LED Voltage Drop Calculator?

Definition: This calculator determines the voltage drop across a resistor when powering an LED from a given supply voltage.

Purpose: It helps electronics enthusiasts and engineers properly design LED circuits by calculating the voltage that needs to be dropped by a current-limiting resistor.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( V_{drop} \) — Voltage to be dropped (volts)
• \( V_{supply} \) — Power supply voltage (volts)
• \( V_{led} \) — LED forward voltage (volts)

Explanation: The supply voltage minus the LED's forward voltage gives the voltage that must be dropped by a resistor to properly limit current.

3. Importance of Voltage Drop Calculation

Details: Proper voltage drop calculation ensures LEDs receive correct current, preventing burnout while achieving optimal brightness.

4. Using the Calculator

Tips: Enter the power supply voltage and the LED's forward voltage (typically 1.8-3.3V depending on color/type). Supply voltage must be greater than LED voltage.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical LED forward voltage?
A: Red LEDs ~1.8-2.2V, green ~2-3.3V, blue/white ~3-3.6V. Check your LED's datasheet for exact value.

Q2: Why is voltage drop important?
A: It determines the resistor value needed to properly limit current through the LED (using Ohm's Law: R = Vdrop/I).

Q3: What if my supply voltage equals LED voltage?
A: No voltage drop means no current limiting - this is dangerous and will likely burn out the LED.

Q4: Can I use this for multiple LEDs?
A: For series LEDs, sum their voltages. For parallel, each needs its own resistor calculated separately.

Q5: What's next after finding voltage drop?
A: Use Ohm's Law (R = Vdrop/I) to calculate the required resistor value for your desired current.