The **KRTBS-121-R** is a specific electronic component produced by **Kingbright**. It is a high-performance **Tri-Color (RGB) Surface Mount (SMD) LED**. These components are widely used in status indicators, backlighting, and decorative lighting where a wide range of colors is required from a single point source. --- ## 1. Technical Specifications The following table highlights the core electrical and optical characteristics of the KRTBS-121-R: | Parameter | Red (R) | Green (G) | Blue (B) | | :--- | :--- | :--- | :--- | | **Material** | AlGaInP | InGaN | InGaN | | **Dominant Wavelength** | 624 nm | 525 nm | 470 nm | | **Luminous Intensity (typ)** | 150 mcd | 400 mcd | 100 mcd | | **Forward Voltage (typ)** | 2.0 V | 3.3 V | 3.3 V | | **Viewing Angle** | 120° | 120° | 120° | | **Max Forward Current** | 30 mA | 30 mA | 30 mA | --- ## 2. Key Features * **Common Anode Configuration:** All three internal LED chips share a single positive terminal, while the cathodes are controlled independently. * **Compact Footprint:** The "121" in the part number often refers to the package size (approx. 1.0 x 1.0 mm), making it ideal for high-density PCB designs. * **Water Clear Lens:** Uses a transparent epoxy to ensure maximum light output and color purity. * **Reflow Solderable:** Compatible with automated SMT (Surface Mount Technology) assembly lines. --- ## 3. Pin Configuration & Wiring To control the device, a microcontroller (like an Arduino or ESP32) typically pulls the cathode pins low to complete the circuit. ### Circuit Example (Conceptual) ```cpp // Example: Setting a purple color (Red + Blue) void setup() { pinMode(RED_CATHODE, OUTPUT); pinMode(GREEN_CATHODE, OUTPUT); pinMode(BLUE_CATHODE, OUTPUT); digitalWrite(COMMON_ANODE, HIGH); // Power to common pin } void loop() { analogWrite(RED_CATHODE, 0); // Fully ON (PWM 0 for low side) analogWrite(GREEN_CATHODE, 255); // Fully OFF analogWrite(BLUE_CATHODE, 0); // Fully ON } ``` --- ## 4. Typical Applications 1. **Consumer Electronics:** Indicator lights for smart home devices (routers, speakers). 2. **Backlighting:** Illuminating LCD screens or membrane switches. 3. **Wearables:** Due to its small form factor and low power consumption. 4. **Automotive:** Dashboard indicators and ambient interior lighting. ---