## MMBT4401L-AE3-R Electronic Component Overview The **MMBT4401L-AE3-R** is a general-purpose **NPN Epitaxial Silicon Transistor** designed for medium-power amplification and switching applications. It is the surface-mount (SMD) equivalent of the classic through-hole 2N4401 transistor. ### 1. Key Technical Specifications | Parameter | Symbol | Maximum Rating | | :--- | :---: | :--- | | Collector-Base Voltage | $V_{CBO}$ | 60 V | | Collector-Emitter Voltage | $V_{CEO}$ | 40 V | | Emitter-Base Voltage | $V_{EBO}$ | 6.0 V | | Collector Current (Continuous) | $I_C$ | 600 mA | | Total Power Dissipation | $P_D$ | 225 - 350 mW (Package dependent) | | Junction Temperature | $T_J$ | -55 to +150 °C | --- ### 2. Operational Characteristics * **Current Gain ($h_{FE}$):** Typically ranges from 100 to 300 at $I_C = 150mA$. This makes it suitable for amplifying small signals into larger currents. * **Switching Speed:** Known for fast switching times (Delay + Rise time $\approx$ 35ns), making it efficient for PWM (Pulse Width Modulation) and logic gate interfaces. * **Saturation Voltage ($V_{CE(sat)}$):** Low saturation voltage (approx. 0.4V at 500mA), which minimizes power loss when the transistor is fully "ON." --- ### 3. Package and Pinout (SOT-23) The "AE3" in the part number typically refers to the **SOT-23** surface-mount package. | Pin Number | Function | Description | | :--- | :--- | :--- | | **1** | **Base** | Controls the flow between Collector and Emitter | | **2** | **Emitter** | Current exits here (NPN configuration) | | **3** | **Collector** | Current enters here | --- ### 4. Typical Applications * **Switching:** Driving LEDs, small DC motors, relays, or solenoid coils. * **Amplification:** Audio pre-amplification or signal processing in RF circuits. * **Level Shifting:** Converting logic signals between different voltage levels (e.g., 3.3V to 5V). --- ### 5. Part Number Breakdown (UTC Standard) * **MMBT4401**: Model series (NPN General Purpose). * **L**: Lead-free / Halogen-free plating. * **AE3**: Package code for SOT-23. * **R**: Tape and Reel packaging.