The **2SC5259** (often abbreviated as **C5259**) is a high-power NPN epitaxial silicon transistor primarily designed for high-voltage and high-speed switching applications. It is frequently found in CRT displays, television horizontal deflection circuits, and industrial power supplies. --- ### ## Technical Specifications The following table summarizes the key electrical characteristics of the C5259 transistor: | Parameter | Symbol | Rating | Unit | | :--- | :--- | :--- | :--- | | Collector-Base Voltage | $V_{CBO}$ | 1500 | V | | Collector-Emitter Voltage | $V_{CEO}$ | 600 | V | | Emitter-Base Voltage | $V_{EBO}$ | 5 | V | | Collector Current (DC) | $I_C$ | 7 | A | | Collector Current (Pulse) | $I_{CP}$ | 14 | A | | Base Current | $I_B$ | 3.5 | A | | Collector Power Dissipation ($T_c = 25^\circ C$) | $P_C$ | 50 | W | | Junction Temperature | $T_j$ | 150 | $^\circ C$ | --- ### ## Key Features and Characteristics 1. **High Voltage Tolerance:** With a $V_{CBO}$ of 1500V, this part is designed to handle the significant voltage spikes generated by inductive loads. 2. **High Speed:** It features low saturation voltage and fast switching times (storage time and fall time), which are critical for efficiency in deflection circuits. 3. **Built-in Damper Diode:** Depending on the specific manufacturer variant (e.g., Toshiba vs. generic clones), some C5259 versions include an integrated **damper diode** between the collector and emitter and a **resistor** between the base and emitter. * *Note: Always check the specific datasheet for the suffix/brand to confirm the internal schematic.* 4. **Package Type:** Typically housed in a **TO-3PF** or **TO-3PL** package, which is a fully isolated or partially isolated plastic package designed for high-power thermal dissipation. --- ### ## Pinout Configuration When looking at the front of the transistor (labels facing you) with the pins pointing downwards: | Pin Number | Function | Description | | :--- | :--- | :--- | | 1 | **Base** | Controls the transistor (Gate) | | 2 | **Collector** | Connected to the load (Highest Voltage) | | 3 | **Emitter** | Usually connected to Ground/Common | --- ### ## Common Applications * **Horizontal Deflection Circuits:** Used in old-style CRT monitors and televisions to control the electron beam. * **Switching Regulators:** High-voltage DC-DC converters. * **Inductive Load Drivers:** Managing motors or solenoids where flyback voltage is a concern. ---