The **C4SMF-RJF** is a high-brightness, oval, through-hole LED manufactured by **Cree LED**. It is specifically designed for full-color video signs and outdoor passenger information displays. --- ### ## Technical Specifications Below are the key electrical and optical characteristics of the C4SMF-RJF: | Parameter | Specification | | :--- | :--- | | **Color** | Red | | **Dominant Wavelength** | 619nm - 624nm | | **Luminous Intensity** | 1100 - 4180 mcd | | **Forward Current ($I_F$)** | 50 mA (Maximum) | | **Forward Voltage ($V_F$)** | 2.1V (Typical) / 2.6V (Maximum) | | **Viewing Angle** | 70° (Horizontal) / 35° (Vertical) | | **Lens Appearance** | Red Diffused | | **Operating Temperature** | -40°C to +100°C | --- ### ### Key Features 1. **Oval Design:** The 4mm oval shape provides a wide horizontal viewing angle (70°) and a narrow vertical viewing angle (35°). This ensures the light is focused toward viewers on the ground/street rather than being wasted pointing at the sky. 2. **High Reliability:** Built using AlInGaP (Aluminum Indium Gallium Phosphide) technology, which offers excellent longevity and stable performance under varying environmental conditions. 3. **UV Resistance:** The epoxy resin contains UV inhibitors to prevent the lens from yellowing or becoming brittle when exposed to direct sunlight for long periods. 4. **Standoff Options:** These LEDs often come with "standoffs" on the leads to ensure proper spacing from the PCB during the soldering process, aiding in heat dissipation and alignment. --- ### ### Typical Applications * **Electronic Passenger Information:** Bus and train station arrival/departure boards. * **Outdoor Video Screens:** Large-scale advertising billboards. * **Variable Message Signs (VMS):** Highway traffic alerts and speed limit signs. * **Commercial Signs:** Retail "Open" signs or promotional displays. --- ### ### Circuit Integration (Example) To drive this LED using a standard 5V logic source, a current-limiting resistor is required. **Calculation:** `R = (V_source - V_forward) / I_target` `R = (5V - 2.1V) / 0.02A (20mA) = 145 Ohms` ```python # Simple Python script to calculate Resistor for C4SMF-RJF def calculate_resistor(v_source, v_forward, current_ma): current_a = current_ma / 1000 resistor = (v_source - v_forward) / current_a return resistor # Output: 145.0 Ohms print(f"Required Resistor: {calculate_resistor(5.0, 2.1, 20)} Ohms") ```