The **2SC3645-R** is a high-frequency NPN epitaxial silicon transistor primarily designed for high-definition video output and high-speed switching applications. It is often found in the circuitry of CRT monitors, video amplifiers, and communication equipment. --- ### 1. Key Technical Specifications The "R" suffix typically denotes a specific **hFE (DC Current Gain)** classification, ensuring predictable performance in amplification circuits. | Parameter | Symbol | Maximum Rating | Unit | | :--- | :--- | :--- | :--- | | Collector-Base Voltage | $V_{CBO}$ | 160 | V | | Collector-Emitter Voltage | $V_{CEO}$ | 160 | V | | Emitter-Base Voltage | $V_{EBO}$ | 5.0 | V | | Collector Current (DC) | $I_C$ | 50 | mA | | Total Power Dissipation | $P_C$ | 800 | mW | | Junction Temperature | $T_j$ | 150 | °C | --- ### 2. Electrical Characteristics These values define how the transistor behaves under standard operating conditions: * **Current Gain ($h_{FE}$):** For the "R" grade, the range is typically between **100 and 200**. * **Transition Frequency ($f_T$):** Approximately **400 MHz**. This high frequency makes it excellent for video signals where rapid switching is required to maintain image clarity. * **Output Capacitance ($C_{ob}$):** Low capacitance (typically around **1.8 pF**), which reduces signal distortion at high frequencies. --- ### 3. Physical Package & Pinout The 2SC3645 is usually housed in a **TO-92L** (also known as the "Large" TO-92) package. This is slightly taller than a standard TO-92 to allow for better heat dissipation. | Pin Number | Assignment | | :--- | :--- | | 1 | Emitter (E) | | 2 | Collector (C) | | 3 | Base (B) | --- ### 4. Typical Applications * **Video Output Stages:** Used in high-resolution displays to drive the cathode ray tube. * **High-Voltage Switching:** Suitable for circuits operating up to 160V. * **RF Amplifiers:** Due to its 400 MHz transition frequency, it can be used in wideband pre-amplifiers. --- ### 5. Equivalent Substitutes If the 2SC3645-R is unavailable, the following parts are often considered as alternatives (check pinouts and voltage ratings before replacing): * **2SC3467** * **2SC3953** * **KSC3503**