The **2SD1664-R** is a high-performance, NPN epitaxial planar silicon transistor. It is widely utilized in power amplification and switching circuits due to its high current capacity and low saturation voltage. --- ## 1. Technical Specifications The "R" suffix in 2SD1664-R typically refers to the **hFE (DC Current Gain)** classification, ensuring the gain falls within a specific range (usually 180 to 390). | Characteristic | Symbol | Rating | Unit | | :--- | :--- | :--- | :--- | | Collector-Base Voltage | $V_{CBO}$ | 40 | V | | Collector-Emitter Voltage | $V_{CEO}$ | 32 | V | | Emitter-Base Voltage | $V_{EBO}$ | 5 | V | | Collector Current (DC) | $I_C$ | 1 | A | | Collector Current (Pulse) | $I_{CP}$ | 2 | A | | Collector Power Dissipation | $P_C$ | 500 | mW | | Junction Temperature | $T_j$ | 150 | °C | --- ## 2. Key Features The 2SD1664-R is designed for efficiency and compact integration: * **Low Saturation Voltage:** Typically $V_{CE(sat)} = 0.5V$ (max) at $I_C = 500mA$, which reduces power loss and heat generation. * **High Current Capacity:** Despite its small SOT-89 package, it can handle a continuous current of 1A. * **Complementary Pair:** Its PNP counterpart is the **2SB1132**, allowing for symmetrical push-pull amplifier designs. --- ## 3. Physical Packaging (SOT-89) This transistor is usually housed in a **SOT-89 (MPT3)** surface-mount package, which provides a balance between small size and thermal dissipation. ### Pinout Configuration: 1. **Base (B):** Input signal control. 2. **Collector (C):** Connected to the larger metal tab for heat sinking. 3. **Emitter (E):** Output/Ground reference. --- ## 4. Common Applications * **Voltage Regulation:** Used in series pass transistors for power supplies. * **Relay/Solenoid Drivers:** High current handling makes it ideal for switching inductive loads. * **Audio Amplification:** Used in the output stages of low-power audio amplifiers. * **DC-DC Converters:** Efficient switching due to low saturation voltage.