## Overview of the 2SC3858 Transistor The **2SC3858** is a high-power NPN epitaxial planar silicon transistor. It is specifically designed for high-fidelity (Hi-Fi) audio power amplifiers and general-purpose high-power switching applications. It is frequently paired with its PNP complement, the **2SA1494**. --- ### Key Technical Specifications The following table summarizes the absolute maximum ratings and electrical characteristics of the 2SC3858: | Parameter | Symbol | Rating | Unit | | :--- | :--- | :--- | :--- | | Collector-Base Voltage | $V_{CBO}$ | 200 | V | | Collector-Emitter Voltage | $V_{CEO}$ | 200 | V | | Emitter-Base Voltage | $V_{EBO}$ | 6 | V | | Collector Current (DC) | $I_C$ | 17 | A | | Base Current | $I_B$ | 5 | A | | Power Dissipation ($T_c = 25°C$) | $P_C$ | 200 | W | | Junction Temperature | $T_j$ | 150 | °C | | Transition Frequency | $f_T$ | 20 | MHz | --- ### Physical and Structural Features * **Package Type:** It usually comes in a **MT-200** package (also known as the "Sanken" style large package). This large footprint is necessary to dissipate the significant heat generated during high-power operation. * **Material:** Silicon NPN. * **Mounting:** It features two mounting holes for secure attachment to large aluminum heat sinks. ### Common Applications 1. **Audio Power Amplifiers:** Due to its high linearity and power handling, it is a staple in "Stage" amplifiers and high-end home audio systems. 2. **DC-to-DC Converters:** Used in power regulation where high current handling is required. 3. **Motor Drivers:** Suitable for driving large DC motors in industrial applications. 4. **Voltage Regulators:** Employed in high-output linear power supplies. --- ### Complementary Pair In push-pull amplifier topologies, the 2SC3858 (NPN) is almost always used alongside the **2SA1494** (PNP). This pairing ensures symmetrical amplification of the positive and negative cycles of the audio signal. ---