The **KRTB-4B2-R/Q** is a high-performance **Tri-color (RGB) LED** manufactured by **Kyocera (formerly Kyocera-Kyoto)**. It is specifically designed for surface-mount technology (SMT) and is widely used in full-color displays and indicators. --- ## 1. Technical Specifications The device integrates three independent LED chips (Red, Green, and Blue) within a single compact package. | Parameter | Red (R) | Green (G) | Blue (B) | | :--- | :--- | :--- | :--- | | **Material** | AlGaInP | InGaN | InGaN | | **Dominant Wavelength** | ~624 nm | ~525 nm | ~470 nm | | **Luminous Intensity** | ~140-280 mcd | ~280-560 mcd | ~71-140 mcd | | **Forward Voltage ($V_F$)** | ~2.1 V | ~3.3 V | ~3.1 V | | **Forward Current ($I_F$)** | 20 mA | 20 mA | 20 mA | --- ## 2. Key Features * **Common Anode Configuration:** The device usually shares a common terminal, allowing for simplified wiring when controlling multiple colors. * **Black Surface Package:** The housing is typically black to enhance contrast ratios in display applications, preventing light washout in bright environments. * **Wide Viewing Angle:** Designed for uniform color mixing and broad visibility. * **Compact Footprint:** Uses a small SMT package (roughly 1.6mm x 1.6mm or similar depending on the specific series variant), making it ideal for high-density PCBs. --- ## 3. Pin Configuration & Circuitry To drive this LED, you must use current-limiting resistors for each color to prevent thermal runaway. Because each color has a different forward voltage ($V_F$), the resistor values will differ. ### Sample Connection (5V Logic) ```cpp // Example Calculation: R = (V_source - V_forward) / I_forward // Red: (5V - 2.1V) / 0.02A = 145 Ohms // Green: (5V - 3.3V) / 0.02A = 85 Ohms // Blue: (5V - 3.1V) / 0.02A = 95 Ohms ``` --- ## 4. Typical Applications 1. **Full-Color Displays:** Used in outdoor/indoor LED screens and signage. 2. **Backlighting:** Providing RGB backlighting for switches, buttons, and LCD panels. 3. **Status Indicators:** Consumer electronics that require multi-state feedback (e.g., Charging=Red, Ready=Green, Bluetooth=Blue). 4. **Automotive:** Interior ambient lighting and dashboard indicators. ---