## Overview of the 2SB772-R Transistor The **2SB772-R** is a popular PNP epitaxial silicon transistor. It is widely used in medium-power applications due to its high current capacity and low saturation voltage. It is frequently paired with its NPN complement, the **2SD882**. --- ### 1. Key Technical Specifications The "R" suffix specifically refers to the **hFE (DC Current Gain)** classification, which typically falls within the 60 to 120 range. | Parameter | Symbol | Maximum Rating | | :--- | :--- | :--- | | Collector-Base Voltage | $V_{CBO}$ | -40 V | | Collector-Emitter Voltage | $V_{CEO}$ | -30 V | | Emitter-Base Voltage | $V_{EBO}$ | -5.0 V | | Collector Current (DC) | $I_C$ | -3.0 A | | Collector Current (Pulse) | $I_{CP}$ | -7.0 A | | Total Power Dissipation | $P_D$ | 1.25 W (Ambient) / 10 W (with Heatsink) | | Junction Temperature | $T_j$ | 150 °C | --- ### 2. Pin Configuration The 2SB772-R is most commonly found in the **TO-126** (also known as SOT-32) package, which allows for easy mounting to a heatsink. 1. **Pin 1 (Emitter):** Current exits the transistor. 2. **Pin 2 (Collector):** Connected to the load (Middle pin/Tab). 3. **Pin 3 (Base):** Controls the flow of current between Emitter and Collector. --- ### 3. Core Characteristics * **Low Saturation Voltage:** Usually $V_{CE(sat)} \approx -0.3V$ at $I_C = -2A$. This reduces heat dissipation and improves efficiency in switching circuits. * **High Current Handling:** Despite its small size, it can handle up to 3 Amps of continuous current. * **Complementary Pair:** Works perfectly with the **2SD882** for Push-Pull amplifier stages or H-Bridge motor drivers. --- ### 4. Common Applications Due to its robust power handling, the 2SB772-R is found in: * **Voltage Regulation:** Used in linear regulators to manage output current. * **Relay Drivers:** Ideal for switching electromagnetic relays due to high $I_C$. * **Audio Amplifiers:** Used in the output stage of medium-power audio systems. * **DC-DC Converters:** Act as a switching element for power conversion. * **Motor Control:** Utilized in H-bridge circuits for small DC motors. --- ### 5. Identification (The "R" Suffix) The 2SB772 is categorized into "Gain Bands" to help engineers select the right sensitivity for their circuits: | Suffix | hFE Range | | :--- | :--- | | **R** | **60 – 120** | | Q | 100 – 200 | | P | 160 – 320 | | E | 200 – 400 |