### Overview of KRTB-312-R The **KRTB-312-R** is a high-performance **Tri-color (RGB) LED** manufactured by Kingbright. It is designed for applications requiring high brightness, color mixing, and surface-mount technology (SMT) compatibility. It typically integrates three separate LED chips (Red, Green, and Blue) into a single compact package. --- ### Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Package Type** | 4-PLCC (Surface Mount) | | **Colors** | Red, Green, Blue (RGB) | | **Common Terminal** | Common Anode or Common Cathode (Check specific sub-variant) | | **Wavelength (Red)** | ~621 nm | | **Wavelength (Green)** | ~525 nm | | **Wavelength (Blue)** | ~470 nm | | **Operating Voltage (Vf)** | Red: 2.0V | Green: 3.3V | Blue: 3.3V | | **Luminous Intensity** | High Output (mcd ratings vary by bin) | --- ### Internal Circuitry and Pinout The device features four pins. In a **Common Anode** configuration (the most standard for this series), the pins are typically assigned as follows: 1. **Pin 1:** Cathode (Blue) 2. **Pin 2:** Cathode (Green) 3. **Pin 3:** Cathode (Red) 4. **Pin 4:** Common Anode (+) #### Driving the Component To control the color, you must use **Pulse Width Modulation (PWM)** on the individual cathode lines. By varying the duty cycle of each color, you can produce millions of color combinations, including white. --- ### Design Considerations 1. **Current Limiting:** Always use series resistors for each color. Because the Forward Voltage ($V_f$) of Red is lower than Green/Blue, the resistor value for Red must be higher to maintain consistent brightness. 2. **Heat Dissipation:** While small, these LEDs can generate heat at maximum brightness. Ensure the PCB layout includes sufficient copper area for thermal relief. 3. **Moisture Sensitivity:** As an SMD component, it has a specific Moisture Sensitivity Level (MSL). It should be baked if it has been exposed to humidity before reflow soldering. --- ### Example Arduino Connection Code If using this LED with a microcontroller, the logic involves setting the common pin to HIGH (for Common Anode) and pulling the RGB pins LOW through resistors. ```cpp // Pin Definitions const int redPin = 9; const int greenPin = 10; const int bluePin = 11; void setup() { pinMode(redPin, OUTPUT); pinMode(greenPin, OUTPUT); pinMode(bluePin, OUTPUT); } void loop() { // Example: Fading to Purple analogWrite(redPin, 127); // 50% brightness analogWrite(greenPin, 0); // Off analogWrite(bluePin, 127); // 50% brightness } ```