## MMBT4401G-AL3-R: Electronic Specifications and Overview The **MMBT4401G-AL3-R** is a widely used **NPN Epitaxial Silicon Transistor** designed for general-purpose switching and amplification applications. It is the surface-mount (SMD) equivalent of the classic 2N4401 through-hole transistor. --- ### 1. Key Technical Specifications The following table summarizes the absolute maximum ratings and electrical characteristics of the device: | Parameter | Symbol | Value | Unit | | :--- | :---: | :---: | :---: | | **Collector-Base Voltage** | $V_{CBO}$ | 60 | V | | **Collector-Emitter Voltage** | $V_{CEO}$ | 40 | V | | **Emitter-Base Voltage** | $V_{EBO}$ | 6.0 | V | | **Collector Current (DC)** | $I_C$ | 600 | mA | | **Total Power Dissipation** | $P_D$ | 350 | mW | | **DC Current Gain** | $h_{FE}$ | 100 - 300 | (@ 150mA) | | **Transition Frequency** | $f_T$ | 250 | MHz (Min) | --- ### 2. Physical & Packaging Details * **Package Type:** SOT-23 (Small Outline Transistor). * **Pin Configuration:** 1. **Base (B)** 2. **Emitter (E)** 3. **Collector (C)** * **Halogen-Free:** The "G" suffix usually denotes a "Green" (halogen-free and RoHS compliant) component. * **Tape and Reel:** The "R" suffix indicates that the part is supplied in a Tape and Reel format for automated SMT assembly. --- ### 3. Functional Applications Due to its high collector current ($600\text{mA}$) and fast switching speeds, this part is commonly found in: 1. **Signal Amplification:** Used in low-noise pre-amplifier stages. 2. **Switching:** Driving LEDs, small relays, or acting as a logic gate inverter. 3. **Pulse Circuits:** High-speed switching thanks to its $250\text{MHz}$ transition frequency. 4. **Driver Stages:** Used in the output stages of low-power radio transmitters or audio equipment. --- ### 4. Comparison: NPN vs. PNP Complement The MMBT4401 (NPN) is frequently paired with its PNP complement, the **MMBT4403**, in push-pull amplifier configurations or H-bridge circuits. ---