MMBT4401 NPN Bipolar Junction Transistor: Pinout, Specification and Applications

MMBT4401 Description

The MMBT4401 is an NPN bipolar junction transistor (BJT) commonly used in switching and amplification applications. It is housed in a small SOT-23 surface-mount package. With a maximum collector current (Ic) of 600mA and a maximum collector-emitter voltage (Vce) of 40V, the MMBT4401 is ideal for low to moderate power tasks. It is frequently employed in applications like signal processing, logic circuits, and driver stages. The transistor also offers high-speed switching characteristics.

MMBT4401 Working Principle

The MMBT4401 operates based on controlling current flow between the collector and emitter terminals through a small current applied to the base. When a sufficient base current is provided, it allows a much larger current to flow from the collector to the emitter, enabling the transistor to function as a switch or amplifier. In the "on" state, the transistor allows current to pass through, and in the "off" state, it blocks current flow, making it useful for switching operations.

MMBT4401 Pinout

Pin 1 (Base)The control terminal that modulates the current between the collector and emitter.

Pin 2 (Emitter)The terminal through which current exits the transistor.

Pin 3 (Collector)The terminal through which current enters the transistor.

MMBT4401 Symbol

MMBT4401 Footprint

MMBT4401 3D Model

MMBT4401 Circuit

MMBT4401 Specification

Parameter	Value
Type	NPN
Package	SOT-23
Collector-Emitter Voltage (Vce)	40V
Collector-Base Voltage (Vcb)	60V
Emitter-Base Voltage (Veb)	6V
Collector Current (Ic)	600mA
Vce Saturation (Max) @ Ib, Ic	750mV @ 50mA, 500mA
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 150mA, 1V
Power Dissipation (Pd)	350mW
DC Current Gain (hFE)	100-300
Transition Frequency (ft)	250 MHz
Operating Temperature	-55°C -150°C

MMBT4401 Features

High Current Handling

Low Saturation Voltage

High Speed

Wide Operating Temperature Range

High DC Current Gain (hFE)

RoHS Compliant

General Purpose

Three Current Gain Groups

MMBT4401 Applications

Switching Circuits

Signal Amplification

Driver Circuits

Logic Circuits

Pulse Width Modulation (PWM) Controls

Oscillators and Timers

Load Switching

Commercial/Industrial Grade

MMBT4401 Package

The MMBT4401 is housed in SOT-23 package, which is a small, surface-mount device (SMD) package widely used in modern electronic designs. The SOT-23 package features three pins, which include the base, emitter, and collector terminals of the transistor. This package is ideal for applications requiring space-saving solutions, offering a low profile and minimal footprint on printed circuit boards (PCBs). The SOT-23 package also enhances thermal performance and supports automated assembly processes.

How to Use MMBT4401?

To use the MMBT4401 transistor in a circuit, follow these steps:

First, connect the Base pin to the input signal or control voltage. This controls the transistor's switching or amplification state. For example, in a switching circuit, connect the Base through a current-limiting resistor to the driving signal.

Next, connect the Collector pin to the load or the positive supply voltage. The load connected to the Collector does not exceed the maximum current rating of the transistor (600mA).

Finally, connect the Emitter pin to the ground or the negative side of the power supply. This completes the circuit and allows current to flow through the transistor when it is in the "on" state.

MMBT4401 Alternatives

The MMBT4401 can be substituted with several equivalent transistors depending on the application requirements. Some common alternatives include the MMBT4401HLT1G, MMBT4401_D87Z, MMBT4401K, MMBT4401WT1, MMBT4401T-7 and MMBT4401M3T5G. These substitutes share similar electrical characteristics.

FAQs

How should the MMBT4401 be connected to a circuit?

Base: Connect to the input signal or control voltage.

Collector: Connect to the load or positive supply voltage.

Emitter: Connect to the ground or negative side of the power supply.

Can the MMBT4401 be used for both digital and analog applications?

Yes, the MMBT4401 can be used in both digital and analog applications. In digital circuits, it is used for switching purposes, while in analog circuits, it serves as an amplifier or driver.

What are the typical failure modes of the MMBT4401?

Typical failure modes include:

Overheating: Due to exceeding power dissipation limits.

Excessive Current: When collector current exceeds its maximum rating.

Voltage Breakdown: If voltages exceed the maximum ratings for Vce, Vcb, or Veb.