The **BU941-TQ2-R** is a high-performance **Silicon NPN Power Darlington Transistor** specifically designed for automotive ignition systems and high-voltage power switching applications. --- ### 1. Key Technical Specifications The device is characterized by its ability to handle high voltages and high current gains (characteristic of Darlington pairs). | Parameter | Symbol | Value | Unit | | :--- | :--- | :--- | :--- | | **Collector-Emitter Voltage** | $V_{CEO(sus)}$ | 400 | V | | **Collector-Emitter Voltage** | $V_{CES}$ | 500 | V | | **Collector Current (DC)** | $I_C$ | 15 | A | | **Collector Current (Peak)** | $I_{CM}$ | 30 | A | | **Power Dissipation ($T_c = 25^\circ C$)** | $P_{tot}$ | 125 | W | | **DC Current Gain** | $h_{FE}$ | 300 (min) | - | | **Package Type** | TO-263 | (Surface Mount) | - | --- ### 2. Internal Structure and Features The "Darlington" configuration means the device contains two transistors integrated into one, where the first amplifies the input for the second. * **Integrated Clamping Diode:** Includes a built-in collector-emitter diode to protect the transistor against inductive kickback (common in ignition coils). * **Monolithic Structure:** Both transistors and the protective elements are on a single silicon chip, ensuring thermal stability. * **High Ruggedness:** Engineered to withstand the harsh electrical environment of automotive engines. --- ### 3. Pin Configuration (TO-263 Package) | Pin Number | Function | Description | | :--- | :--- | :--- | | **1** | **Base** | Input signal to trigger the transistor | | **2** | **Collector** | Connected to the load (e.g., Ignition Coil) | | **3** | **Emitter** | Ground/Return path | | **Tab** | **Collector** | The metal tab is internally connected to the collector for heat dissipation | --- ### 4. Typical Applications The BU941-TQ2-R is primarily found in: 1. **Electronic Ignition Systems:** Switching the primary current of an ignition coil to generate high-voltage sparks. 2. **High Voltage Switching:** Controlling DC loads that require high voltage isolation and high current. 3. **Solenoid/Relay Drivers:** Driving heavy inductive loads where back-EMF protection is required. --- ### 5. Ordering Suffix Meaning * **BU941:** Part series number. * **TQ2:** Refers to the **TO-263** (D2PAK) package style. * **R:** Generally indicates **Tape and Reel** packaging for automated SMT (Surface Mount Technology) assembly.