The **2SB1220-R** is a specific variant of the 2SB1220 Silicon PNP Epitaxial Planar Transistor. It is primarily designed for low-frequency power amplification and low-speed switching applications. --- ### 1. Key Technical Specifications The "R" suffix typically denotes the **hFE (DC Current Gain)** classification, ensuring the transistor operates within a specific gain range. | Parameter | Symbol | Value | Unit | | :--- | :--- | :--- | :--- | | Collector-Base Voltage | $V_{CBO}$ | -25 | V | | Collector-Emitter Voltage | $V_{CEO}$ | -20 | V | | Emitter-Base Voltage | $V_{EBO}$ | -5 | V | | Collector Current (DC) | $I_C$ | -0.7 | A | | Collector Power Dissipation | $P_C$ | 250 | mW | | Junction Temperature | $T_j$ | 150 | °C | | hFE Classification (R) | $h_{FE}$ | 180 to 390 | - | ### 2. Physical and Electrical Characteristics * **Package Type:** Usually comes in a **Mini-type 3-pin package** (similar to SOT-23 or SOT-89 depending on the manufacturer, commonly Panasonic). * **Polarity:** **PNP**. This means the device is "on" when the base is pulled low relative to the emitter. * **Complementary Part:** The NPN counterpart is the **2SD1819**, often used together in push-pull amplifier circuits. ### 3. Pin Configuration Standard layout for the Mini-3P package: 1. **Base (B):** Controls the current flow between Emitter and Collector. 2. **Emitter (E):** The source of the charge carriers. 3. **Collector (C):** Where the current exits the device. --- ### 4. Typical Applications The 2SB1220-R is optimized for small-signal processing and moderate power switching: * **Audio Amplification:** Used in the pre-amplifier stages of portable audio devices. * **Driver Circuits:** Acting as a switch to drive small relays, LEDs, or other transistors. * **Voltage Regulation:** Part of linear voltage regulator circuits to provide stable DC output. --- ### 5. Selection Guide (hFE Grades) Transistors in this series are binned by their current gain. The **R** grade is the middle-to-high gain tier: * **Q:** 120 to 240 * **R:** 180 to 390 (The model in question) * **S:** 290 to 600