## Technical Overview: 2SC4774L-AL3-R The **2SC4774L-AL3-R** is a specific NPN Silicon Epitaxial Planar Transistor. It is primarily designed for general-purpose switching and amplification applications where space-saving and low-power consumption are critical. --- ### 1. Key Technical Specifications The table below summarizes the absolute maximum ratings and primary characteristics of the device. | Parameter | Symbol | Maximum Rating | Unit | | :--- | :--- | :--- | :--- | | Collector-Base Voltage | $V_{CBO}$ | 60 | V | | Collector-Emitter Voltage | $V_{CEO}$ | 50 | V | | Emitter-Base Voltage | $V_{EBO}$ | 7 | V | | Collector Current (DC) | $I_C$ | 150 | mA | | Power Dissipation | $P_D$ | 150 | mW | | Junction Temperature | $T_j$ | +150 | °C | | Transition Frequency | $f_T$ | 180 (Typ) | MHz | --- ### 2. Component Features * **Low Collector Saturation Voltage:** Typically $V_{CE(sat)} = 0.4V$ at $100mA$, which ensures minimal power loss during switching. * **High Current Gain ($h_{FE}$):** Usually falls within the 120 to 560 range, allowing for efficient signal amplification. * **Small Package:** Housed in the **SOT-23** (or similar small-outline) package, ideal for high-density PCB layouts. * **Complementary Part:** The PNP counterpart for this transistor is generally the **2SA1774L**. --- ### 3. Part Number Decoding (UTC Standard) The suffix and prefix provide specific information about the manufacturing and packaging: | Segment | Meaning | | :--- | :--- | | **2SC4774** | Part Number (NPN Transistor) | | **L** | Lead-free plating (Halogen-free/RoHS compliant) | | **AL3** | Package code (Typically refers to SOT-23) | | **R** | Tape and Reel packaging | --- ### 4. Typical Applications * **Switching:** Used in digital circuits to turn small loads (LEDs, relays) on/off. * **Amplification:** Low-noise pre-amplifiers for audio or sensor signals. * **Driver Circuits:** Acting as a buffer for microcontroller output pins. --- ### 5. Simple Switching Circuit Example In a standard switching configuration, the transistor acts as an electronically controlled switch. ```cpp // Logic Representation: // Base (B) high -> Collector (C) to Emitter (E) conducts (ON) // Base (B) low -> Collector (C) to Emitter (E) blocks (OFF) [VCC] --- [Load] --- [Collector] | [Input] --- [Resistor] --- [Base] | [Emitter] --- [GND] ```