LED 3mm (Green)

Description

The 3mm Green LED is a small and efficient Light Emitting Diode (LED) that emits green light when current flows through it. It is commonly used in a variety of applications such as indicators, displays, and decorative lighting due to its small size, low power consumption, and bright illumination.

Overview of 3mm Green LED:

• Package Size: 3mm (standard size for small, low-power LEDs)
• Color: Green (emits green light, typically around 520–570 nm in wavelength)
• Transparency: Transparent lens (often made of clear plastic), allowing the light to be emitted without much color filtering or diffusion.
• Typical Forward Voltage: 2.0V to 3.0V (typically around 2.2V for green LEDs)
• Typical Forward Current: 20mA (standard operating current)
• Luminous Intensity: Typically 150-250mcd (millicandela), depending on the specific model.
• Power Dissipation: Low power consumption, typically around 20mA current draw.

Pin Configuration:

An LED typically has two pins:

• Anode (+): The longer leg (positive terminal).
• Cathode (-): The shorter leg (negative terminal).

For a 3mm Green LED, the pinout is:

• Anode (+): Connect to the positive side of the power supply or circuit.
• Cathode (-): Connect to the negative side of the circuit (ground).

Electrical Characteristics of a 3mm Green LED:

• Forward Voltage (Vf): The voltage drop across the LED when it is forward-biased (i.e., when current is flowing through it). For a green LED, this voltage is typically between 2.0V and 3.0V.
• Forward Current: 20mA is the typical current value used to drive the LED for optimal brightness. Going beyond the rated current can overheat and damage the LED.

Applications of 3mm Green LED:

1. Indicator Lights:
   • 3mm green LEDs are often used in electronics as status indicators, such as power indicators, switches, or circuit boards. Green LEDs are often used to indicate a “working” or “active” state in devices.
2. Displays:
   • Used in seven-segment displays, digital clocks, or alphanumeric displays, where the green LED provides a clear and vibrant visual appearance.
3. Lighting:
   • Decorative lighting in electronics, signs, or small lamps. Green LEDs are often used in LED strips or accent lighting for creating a unique lighting effect.
4. Automotive Lighting:
   • Many automotive applications use green LEDs for dashboard lights, indicator lights, or decorative lighting.
5. Toys and Gadgets:
   • Commonly found in toys, gadgets, and other consumer electronics where small, bright lights are needed.
6. Signals and Alarms:
   • Green LEDs can be used for signal lights or as part of alarm systems for visual signaling.
7. Status Indicators:
   • Green LEDs are often used in electronic devices to show that the system is powered on or functioning properly.

Current Limiting Resistor:

When using a 3mm Green LED, it’s essential to use a current-limiting resistor to prevent excessive current, which could damage the LED. The resistor limits the current flowing through the LED.

How to Calculate the Resistor Value:

The general formula for calculating the current-limiting resistor for an LED is:

R=Vsupply−VfIfR = \frac{V_{supply} – V_f}{I_f}

Where:

• V_supply is the voltage supplied to the circuit.
• V_f is the forward voltage of the LED (typically 2.2V for a green LED).
• I_f is the desired forward current (typically 20mA = 0.02A).

Example:

If you are using a 5V power supply:

• V_supply = 5V
• V_f = 2.2V (green LED forward voltage)
• I_f = 20mA (typical forward current)

Substituting the values into the formula:

R=5V−2.2V0.02A=2.8V0.02A=140ΩR = \frac{5V – 2.2V}{0.02A} = \frac{2.8V}{0.02A} = 140\Omega

So, you would need a 140Ω resistor in series with the LED. A 150Ω resistor is a common standard value and would work well.

Brightness and Efficiency:

• Luminous Intensity: The brightness of a green LED is typically measured in millicandela (mcd). A typical 3mm green LED has a luminous intensity of around 150 to 250mcd, depending on the specific model and manufacturer. This makes it quite bright for such a small package.
• Power Consumption: The power consumed by the green LED is relatively low (in the range of 0.06W for typical current values), which makes green LEDs ideal for low-power applications.