## Technical Overview of the HLMP-AD16-RST The **HLMP-AD16-RST** is a high-brightness, precision optical performance Oval LED, manufactured by Broadcom (formerly Avago). These LEDs are specifically designed for full-color outdoor signs and passenger information signs. --- ### 1. Key Technical Specifications The following table summarizes the primary electrical and optical characteristics of the HLMP-AD16-RST: | Parameter | Specification | | :--- | :--- | | **Color** | Red | | **Dominant Wavelength** | 626 nm | | **Luminous Intensity** | 460 mcd (Min) to 1150 mcd (Max) | | **Viewing Angle** | 70° x 35° (Oval) | | **Forward Current ($I_F$)** | 20 mA (Typical) | | **Forward Voltage ($V_F$)** | 2.0 V to 2.4 V | | **Lens Shape** | Oval (Subminiature) | | **Package Type** | T-1 ¾ (5mm) Round Base | --- ### 2. Core Electronic Features * **Oval Radiation Pattern:** Unlike standard round LEDs, this part features a specialized radiation pattern (70 degrees horizontal and 35 degrees vertical). This ensures that light is directed towards the audience rather than wasted towards the sky or ground. * **Material Technology:** It utilizes **AlInGaP (Aluminum Indium Gallium Phosphide)** technology. This material is chosen for its high light output efficiency and excellent stability over long periods and varying temperatures. * **Tinted and Diffused Lens:** The LED lens is tinted and diffused, which improves the contrast ratio, making the LED appear clearly "off" when not powered, even in direct sunlight. * **Standoff Options:** The "RST" suffix usually indicates specific packaging or lead configurations, often including "standoffs" on the leads to ensure proper airflow and consistent seating on a PCB. --- ### 3. Application Use-Cases 1. **Variable Message Signs (VMS):** Used in highway traffic alerts and speed limit signs. 2. **Outdoor Advertising:** Large-scale LED billboards where wide horizontal visibility is required. 3. **Transportation:** Passenger information displays at bus stops or train stations. --- ### 4. Circuit Implementation Example To drive the HLMP-AD16-RST using a 5V DC source, you must use a current-limiting resistor to prevent burnout. **Calculation:** $R = (V_{source} - V_{forward}) / I_{forward}$ $R = (5V - 2.0V) / 0.02A = 150 \Omega$ ```cpp // Example: Basic Arduino Blink Structure for HLMP-AD16 void setup() { pinMode(13, OUTPUT); // Connect LED via 150-220 ohm resistor } void loop() { digitalWrite(13, HIGH); // Turn LED on delay(1000); digitalWrite(13, LOW); // Turn LED off delay(1000); } ```