## 2SC4915-R Electronic Component Overview The **2SC4915-R** is a NPN epitaxial silicon transistor designed primarily for **High-Frequency (HF) amplification** and high-speed switching applications. It is commonly found in RF stages of FM tuners, VHF amplifiers, and communication equipment. ### 1. Key Technical Specifications The "R" suffix typically denotes the **hFE (DC Current Gain) classification**, indicating a specific range of gain performance. | Parameter | Symbol | Rating / Value | | :--- | :--- | :--- | | **Type** | Polar | NPN | | **Collector-Base Voltage** | $V_{CBO}$ | 30 V | | **Collector-Emitter Voltage** | $V_{CEO}$ | 20 V | | **Emitter-Base Voltage** | $V_{EBO}$ | 4 V | | **Collector Current** | $I_C$ | 50 mA | | **Transition Frequency** | $f_T$ | 550 MHz (Typical) | | **Collector Capacitance** | $C_{ob}$ | 0.9 pF (Typical) | | **Package Type** | SSS-Mini | SOT-523 / SSM | --- ### 2. Features and Advantages * **Low Noise Figure:** Excellent for sensitive signal reception in RF circuits. * **High Transition Frequency ($f_T$):** Capable of operating at frequencies up to several hundred megahertz, making it ideal for VHF bands. * **Small Footprint:** Usually packaged in SOT-523 (SSM), which is critical for compact modern PCB designs. * **Low Capacitance:** The low output capacitance ($C_{ob}$) minimizes signal loss at high frequencies. --- ### 3. Pin Configuration The device is a three-terminal surface-mount component. Looking at the top with the two pins at the bottom: 1. **Base (B):** Controls the current flow between Collector and Emitter. 2. **Emitter (E):** The lead where current exits the transistor. 3. **Collector (C):** The lead where current enters the transistor. --- ### 4. Typical Applications * **RF Amplifiers:** Used in the front-end of radio receivers to boost weak signals. * **Frequency Mixers:** Utilized in superheterodyne receivers. * **Oscillators:** Found in local oscillator circuits for signal generation. * **High-Speed Switching:** Suitable for digital circuits requiring rapid state changes.