The **B772C-R** (often labeled simply as B772) is a popular PNP power transistor widely used in audio amplification and general-purpose switching circuits. It is the PNP complement to the D882 NPN transistor. --- ### 1. General Specifications The "R" suffix typically refers to the **hFE (DC Current Gain)** classification, indicating a specific gain range. | Parameter | Value/Description | | :--- | :--- | | **Transistor Type** | PNP | | **Material** | Silicon | | **Package Type** | TO-126 (standard) or SOT-89 (SMD) | | **Max Collector Current ($I_C$)** | -3.0 Amperes | | **Max Collector-Emitter Voltage ($V_{CEO}$)** | -30 Volts | | **Max Collector-Base Voltage ($V_{CBO}$)** | -40 Volts | | **Max Power Dissipation ($P_D$)** | 10 Watts (with heatsink) | | **DC Current Gain ($h_{FE}$)** | 100 to 200 (for 'R' grade) | --- ### 2. Pinout Configuration When looking at the front (labeled side) of a TO-126 package, the pins are arranged as follows: 1. **Pin 1 (Emitter):** Current flows out of this pin in a PNP configuration. 2. **Pin 2 (Collector):** Usually connected to the load. 3. **Pin 3 (Base):** The control pin; triggered by a negative voltage relative to the emitter. --- ### 3. Key Characteristics * **Low Saturation Voltage:** It has a low $V_{CE(sat)}$, meaning it is efficient when fully turned "ON," wasting less power as heat. * **High Current Capability:** Despite its small size, it can handle up to 3A, making it suitable for driving motors or relays. * **Complementary Pair:** It is designed to work alongside the **D882** (NPN) for push-pull amplifier stages. --- ### 4. Common Applications * **Voltage Regulation:** Used in linear regulators to maintain steady output. * **Relay Drivers:** High current handling allows it to switch heavy mechanical relays. * **Audio Amplifiers:** Used in the output stage of low-to-medium power audio systems. * **DC-DC Converters:** Acts as a high-speed switch in power conversion circuits. --- ### 5. Implementation Example (Switching) ```cpp // Schematic Logic for a PNP Switch (B772) // [Emitter] -> Connected to VCC (+12V) // [Collector] -> Connected to Load (Motor/LED) -> Ground // [Base] -> Connected to MCU via Resistor // Logic: Pulling the Base LOW turns the transistor ON. ```