## 2SC3647-R: High-Voltage NPN Power Transistor The **2SC3647-R** is an NPN epitaxial silicon transistor designed primarily for high-voltage switching and driving applications. It is commonly used in color TV chroma circuits, video output stages, and high-speed switching power supplies. --- ### 1. Key Technical Specifications The following table summarizes the absolute maximum ratings and electrical characteristics for the 2SC3647-R variant. | Parameter | Symbol | Rating / Value | | :--- | :--- | :--- | | **Type** | Polaritity | NPN | | **Collector-Base Voltage** | $V_{CBO}$ | 120 V | | **Collector-Emitter Voltage** | $V_{CEO}$ | 100 V | | **Emitter-Base Voltage** | $V_{EBO}$ | 5 V | | **Collector Current (DC)** | $I_C$ | 2.0 A | | **Collector Power Dissipation** | $P_C$ | 1.0 W (Free air) | | **DC Current Gain ($h_{FE}$)** | **R Class** | **100 to 200** | | **Transition Frequency** | $f_T$ | 120 MHz (Typ) | | **Package Type** | Case | TO-126 (or similar) | --- ### 2. The Significance of the "-R" Suffix In Japanese industrial transistor naming (JIS), the letter following the part number usually denotes the **Current Gain ($h_{FE}$)** classification. For the 2SC3647: * **R:** 100 to 200 * **S:** 140 to 280 * **T:** 200 to 400 Selecting the "R" grade ensures a specific range of amplification, which is critical for circuit stability and bias matching. --- ### 3. Features & Applications #### Features * **Low Saturation Voltage:** $V_{CE(sat)}$ is typically low (around 0.5V max at $I_C=1A$), reducing power loss during switching. * **High Speed:** A high transition frequency ($f_T$) of 120 MHz allows it to handle video signals and high-frequency pulses without significant distortion. * **High Voltage:** Capable of handling up to 100V, making it robust against voltage spikes in inductive loads. #### Common Applications 1. **Video Output:** Used in CRT displays and professional video equipment for driving high-voltage video signals. 2. **Power Switching:** Acting as a driver in DC-DC converters. 3. **Relay Drivers:** Handling the back-EMF and current requirements of mechanical relays. 4. **Audio Amplifiers:** Used in the driver stage of medium-power audio amplifiers. --- ### 4. Basic Pinout Configuration When looking at the front (labeled side) of a TO-126 package: ```text _______ | O | (Mounting Hole) |_______| | | |2SC3647| |___R___| | | | 1 2 3 E C B ``` 1. **Emitter (E)** 2. **Collector (C)** 3. **Base (B)** ---