The **2SD1280-R** is a high-performance NPN silicon epitaxial planar transistor. It is primarily designed for high-current applications and is commonly used in low-frequency power amplification and power switching circuits. --- ## 1. Technical Specifications The following table outlines the absolute maximum ratings and key electrical characteristics of the 2SD1280-R (at $T_a = 25^\circ C$). | Parameter | Symbol | Rating | Unit | | :--- | :--- | :--- | :--- | | Collector-Base Voltage | $V_{CBO}$ | 20 | V | | Collector-Emitter Voltage | $V_{CEO}$ | 15 | V | | Emitter-Base Voltage | $V_{EBO}$ | 5 | V | | Collector Current (DC) | $I_C$ | 1 | A | | Collector Current (Pulse) | $I_{CP}$ | 2 | A | | Collector Power Dissipation | $P_C$ | 600 | mW | | Junction Temperature | $T_j$ | 150 | $^\circ C$ | --- ## 2. Key Features The 2SD1280-R is distinguished by several performance characteristics that make it suitable for power-dense electronic designs: * **Low Saturation Voltage:** It features a very low collector-emitter saturation voltage ($V_{CE(sat)}$), typically around 0.1V to 0.3V at high currents. This minimizes power loss and heat generation. * **High Current Capacity:** Despite its small footprint, it can handle a continuous DC current of up to 1A. * **The "R" Classification:** The suffix "R" refers to the **hFE (Current Gain)** rank. In this specific series, the R-rank typically signifies a gain range between **180 and 390**. * **Package Type:** It is usually found in a **TO-92L** (long) or similar small-signal plastic package, which offers better heat dissipation than the standard TO-92. --- ## 3. Typical Applications Because of its high current handling and low saturation voltage, the 2SD1280-R is frequently used in: 1. **Voltage Regulators:** Acting as a pass transistor in linear power supplies. 2. **Relay Drivers:** Switching inductive loads where high peak currents occur. 3. **Audio Amplifiers:** Specifically in the output stage of low-power portable audio devices. 4. **DC-DC Converters:** Used in switching circuits for portable electronics. --- ## 4. Pin Configuration When looking at the flat side of the TO-92L package with the leads pointing down: 1. **Emitter (E)** 2. **Collector (C)** 3. **Base (B)** *(Note: Always verify the specific manufacturer's datasheet as pinouts can occasionally vary by region/brand.)*