The **AND1743FST-LED** is a specific high-intensity, surface-mount (SMD) Light Emitting Diode (LED) component often used in industrial displays, backlighting, and signaling applications. --- ### 1. General Specifications The AND1743FST series typically refers to AlGaInP (Aluminum Gallium Indium Phosphide) or similar high-efficiency LED technology. Below is a breakdown of its primary technical characteristics: | Parameter | Typical Value | Unit | | :--- | :--- | :--- | | **Package Type** | Surface Mount (SMD) | - | | **Color** | Red / Super Bright Red | - | | **Luminous Intensity** | 40 - 150 (varies by bin) | mcd | | **Forward Voltage ($V_f$)** | 1.8V - 2.4V | Volts | | **Forward Current ($I_f$)** | 20 | mA | | **Viewing Angle** | 120 - 140 | Degrees | --- ### 2. Key Electronic Components & Materials To understand how this part functions, it is helpful to look at its internal construction: * **Semiconductor Die:** Uses AlGaInP technology, which allows for high brightness with low power consumption compared to older GaAsP LEDs. * **Lead Frame:** Provides the electrical connection points (Anode and Cathode) and acts as a heat sink to dissipate thermal energy. * **Encapsulation:** Usually a clear or water-clear epoxy resin that protects the die and helps shape the light output (beam angle). * **Flat Top Design:** The "FST" in the part number often denotes a "Flat Standard" or "Flat Top" lens profile, which allows for a wider viewing angle and lower profile for thin PCB designs. --- ### 3. Circuit Implementation When integrating the AND1743FST-LED into a circuit, a current-limiting resistor is mandatory to prevent thermal runaway. #### Standard Wiring Diagram (5V Supply) ```text [VCC (+5V)] --- [Resistor (R)] --- [LED (Anode)] --- [LED (Cathode)] --- [GND (0V)] ``` #### Resistor Calculation Example: To run the LED at 20mA ($0.02A$) with a 5V source and a Forward Voltage of 2.0V: `R = (V_source - V_forward) / I_forward` `R = (5V - 2.0V) / 0.02A = 150 Ohms` --- ### 4. Typical Applications * **Status Indicators:** Power-on lights for consumer electronics. * **Backlighting:** Illuminating LCD screens or membrane switches. * **Signage:** Small-scale dot matrix displays or path lighting. * **Automotive:** Internal dashboard indicators. ---