The **2SA1729-R** is a high-speed, high-voltage switching PNP power transistor. It is commonly used in industrial and consumer electronics for power supply circuits and motor control. --- ## 1. Key Specifications The 2SA1729-R belongs to the PNP bipolar junction transistor (BJT) family. Below are its primary electrical characteristics: | Parameter | Symbol | Rating | | :--- | :--- | :--- | | **Collector-Base Voltage** | $V_{CBO}$ | -100 V | | **Collector-Emitter Voltage** | $V_{CEO}$ | -100 V | | **Emitter-Base Voltage** | $V_{EBO}$ | -7 V | | **Collector Current (DC)** | $I_C$ | -5 A | | **Collector Current (Pulse)** | $I_{CP}$ | -10 A | | **Collector Power Dissipation** | $P_C$ | 25 W (with heat sink) | | **Junction Temperature** | $T_j$ | 150 °C | --- ## 2. Package and Pinout The device typically comes in a **TO-220** or **TO-220F** (Full Pack) housing, which allows for easy mounting to a heat sink to manage thermal dissipation. ### Pin Configuration: 1. **Base (B):** Controls the current flow between the collector and emitter. 2. **Collector (C):** The terminal where the majority of current enters. 3. **Emitter (E):** The terminal where current exits. --- ## 3. Notable Features * **High-Speed Switching:** It has a very low storage time ($t_{stg}$) and fall time ($t_f$), making it efficient for high-frequency applications. * **Low Saturation Voltage:** $V_{CE(sat)}$ is typically low, which reduces power loss when the transistor is in the "ON" state. * **Complementary Pair:** It is often paired with the **2SC4511-R** (NPN version) for push-pull amplification or H-bridge circuits. * **The "-R" Suffix:** This usually indicates the **hFE (DC Current Gain)** classification. In this case, "R" typically represents a gain range of approximately 60 to 120 (though this can vary slightly by manufacturer). --- ## 4. Typical Applications The 2SA1729-R is versatile and found in the following circuits: * **DC-DC Converters:** Used as a switching element to regulate voltage. * **High-Power Amplifiers:** Specifically in the output stage of audio equipment. * **Solenoid/Relay Drivers:** Handling the inductive loads of mechanical components. * **Motor Control:** Part of an H-bridge for controlling the direction of DC motors. ---