The term **LED490** typically refers to a Light Emitting Diode that emits light at a peak wavelength of **490 nanometers (nm)**. This specific wavelength falls within the **Cyan (Blue-Green)** spectrum of visible light. Below is an overview of the electronic components, specifications, and characteristics associated with these parts. --- ### 1. Physical and Chemical Composition The electronics of an LED490 are defined by the semiconductor materials used to create the photon emission at that specific frequency. | Component | Description | | :--- | :--- | | **Semiconductor Material** | Usually **Indium Gallium Nitride (InGaN)**. The ratio of Indium determines the 490nm wavelength. | | **Substrate** | Typically Sapphire or Silicon Carbide (SiC). | | **Encapsulation** | Clear epoxy or silicone resin to allow maximum light transmission. | | **Electrodes** | Anode (+) and Cathode (-) leads made of silver-plated copper or gold-wire bonds. | --- ### 2. Electrical Characteristics To operate an LED490 safely, you must adhere to its typical electronic ratings. *Note: Values may vary slightly by manufacturer (e.g., Cree, Osram, or generic).* | Parameter | Typical Value | | :--- | :--- | | **Peak Wavelength** | 485nm – 495nm | | **Forward Voltage ($V_f$)** | 3.0V – 3.6V DC | | **Forward Current ($I_f$)** | 20mA (Standard) to 700mA+ (High Power) | | **Viewing Angle** | 15° to 120° (depending on lens shape) | | **Luminous Intensity** | Measured in mcd (millicandela) or Lumens | --- ### 3. Key Electronic Components in a Circuit When integrating an LED490 into a device, the following electronic parts are required: #### A. Current Limiting Resistor LEDs are current-driven devices. Without a resistor, the LED will draw too much current and burn out. * **Formula:** $R = (V_{source} - V_f) / I_f$ #### B. Constant Current Driver For high-power 490nm LEDs (used in medical or architectural lighting), a switching regulator or constant current IC is used to maintain steady brightness regardless of voltage fluctuations. #### C. Heat Sink Because InGaN LEDs generate heat at the junction, high-wattage 490nm LEDs require an aluminum PCB (Metal Core PCB) or an external heat sink to prevent thermal runaway. --- ### 4. Applications of 490nm Cyan LEDs The 490nm wavelength is unique and used in specific electronic fields: * **Medical Devices:** Used in phototherapy and pulse oximetry. * **Biotechnology:** Excitation light source for certain fluorescent proteins (GFP). * **Underwater Lighting:** Cyan light penetrates water more effectively than red or yellow light. * **Traffic Signals:** Often used in the "Green" light of signals to ensure visibility for color-blind individuals (Blue-Green shift).