### Overview of the 2SC1740S-R The **2SC1740S-R** is an NPN epitaxial planar silicon transistor commonly used for general-purpose switching and amplification. It belongs to the 2SC1740 series, known for its low noise and high reliability in small-signal applications. --- ### Key Technical Specifications Below are the absolute maximum ratings and electrical characteristics for the **R** hFE (current gain) rank of this transistor. | Parameter | Symbol | Rating / Value | Unit | | :--- | :--- | :--- | :--- | | **Collector-Base Voltage** | $V_{CBO}$ | 50 | V | | **Collector-Emitter Voltage** | $V_{CEO}$ | 40 | V | | **Emitter-Base Voltage** | $V_{EBO}$ | 5 | V | | **Collector Current (DC)** | $I_C$ | 150 | mA | | **Power Dissipation** | $P_D$ | 300 | mW | | **DC Current Gain** | $h_{FE}$ | 180 to 390 (R Rank) | - | | **Transition Frequency** | $f_T$ | 180 (Typ.) | MHz | --- ### Package and Pinout The "S" suffix usually denotes a specific package variation. For the 2SC1740S, it typically uses the **SPT (Standard PC Terminal)** package, which is a small-form-factor plastic package similar to a slim TO-92. #### Pin Configuration: 1. **Emitter (E)** 2. **Collector (C)** 3. **Base (B)** --- ### Distinctive Features * **Low Collector Saturation Voltage:** Typically $V_{CE(sat)} = 0.4V$ at $I_C = 50mA$. * **High Reliability:** Designed for consistent performance in low-power circuits. * **Complementary Pair:** Often paired with the **2SA933S** (PNP version) for push-pull amplifier stages. * **Classification:** The "R" indicates the $h_{FE}$ classification (gain range of 180–390). Other ranks include Q (120–270) and S (270–560). --- ### Common Applications 1. **Small Signal Amplification:** Pre-amplifier stages for audio and radio frequency signals. 2. **Switching:** Driving small loads like LEDs, relays, or acting as a logic gate in discrete circuits. 3. **Signal Processing:** Used in consumer electronics like TVs, radios, and communication equipment. ---