## Technical Overview of C4SMN-RJF The **C4SMN-RJF** is a high-performance, **Oval Through-Hole LED** manufactured by **Cree LED** (now part of SGH). It is specifically designed for outdoor video screens, digital signage, and variable-message signs. ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Color** | Red | | **Dominant Wavelength** | 619nm - 624nm | | **Luminous Intensity** | 1100 - 2130 mcd | | **Viewing Angle** | 70° (Horizontal) / 35° (Vertical) | | **Lens Type** | Red Diffused / Tinted | | **Package Shape** | 4mm Oval (Through-Hole) | | **Forward Current** | 50 mA (Maximum) | | **Forward Voltage** | 2.1V (Typical) | --- ### 2. Core Components and Design #### A. Semiconductor Die The device utilizes **AlInGaP** (Aluminium Indium Gallium Phosphide) technology. This material is chosen for red LEDs because it offers high luminous efficiency and stability across various temperatures, which is critical for outdoor environments. #### B. The Oval Lens Unlike standard round LEDs, the C4SMN-RJF features an **oval-shaped epoxy lens**. * **Purpose:** To create a wider viewing angle horizontally (70°) than vertically (35°). * **Benefit:** This ensures that people viewing a large outdoor screen from the sides can still see a clear image, while light is not "wasted" shining toward the sky or the ground. #### C. Lead Frame and Standoffs The LED is a "Through-Hole" component. It typically comes with **standoffs** (small bumps on the leads) that ensure the LED sits at a consistent height on the PCB, which is vital for maintaining a flat, uniform display surface. --- ### 3. Key Electronic Characteristics * **UV Resistance:** The epoxy contains UV inhibitors to prevent the lens from yellowing or becoming brittle when exposed to direct sunlight for years. * **High Brightness:** With an intensity reaching up to 2130 mcd, it remains visible even in direct sunlight. * **Common Anode/Cathode:** As a discrete component, it has two leads. The longer lead is typically the **Anode (+)** and the shorter is the **Cathode (-)**. --- ### 4. Typical Application Circuit When driving this LED, a current-limiting resistor is required to prevent burnout. ```python # Formula: R = (V_source - V_forward) / I_forward # Example Calculation: V_source = 5.0 # Volts V_forward = 2.1 # Volts I_target = 0.02 # 20mA (Safe operating current) Resistance = (5.0 - 2.1) / 0.02 # Result: 145 Ohms ```