2N4402 Pinout, Specifications, Operating Characteristics

FREE-SKY (HK) ELECTRONICS CO.,LIMITED / 12-17 17:35

Understanding 2N4402 pinout, specifications, operating characteristics, and actual circuit behavior is essential for selecting and applying it correctly in electronic designs. This article will discuss the 2N4402 transistor’s overview, pin configuration, specifications, equivalents, features, working principles in various circuits, applications, advantages, limitations, and manufacturer background.

Catalog

1. 2N4402 Transistor Overview

2. 2N4402 Pinout Details

3. 2N4402 Alternatives & Equivalents

4. 2N4402 Transistor Specifications

5. 2N4402 Electrical Characteristics

6. 2N4402 Transistor Features

7. 2N4402 Transistor Working in Circuit

8. 2N4402 Wide Applications

9. 2N4402 Mechanical Dimensions

10. Advantages & Limitations

11. Manufacturer

2N4402 Transistor Overview

The 2N4402 is a general-purpose PNP silicon transistor. It is designed for low-power switching and amplification tasks. With its compact TO-92 through-hole package, the 2N4402 is easy to handle and suitable for breadboards and PCB designs.

This transistor supports moderate voltage and current levels, making it ideal for driving small loads, signal conditioning, and complementary pair designs alongside NPN transistors. As a PNP device, it conducts when the base is driven lower than the emitter, allowing it to work effectively in high-side switching and amplifier configurations.

If you are interested in purchasing the 2N4402, feel free to contact us for pricing and availability.

2N4402 Pinout Details

Pin Number	Pin Name	Description
1	Collector (C)	Collects current flowing through the transistor
2	Base (B)	Controls the transistor’s switching and amplification
3	Emitter (E)	Emits current when the transistor is turned ON

2N4402 Alternatives & Equivalents

Equivalent Model

• 2N4403

• NTE159

• PN4402

Alternative Substitute

• BC327

• BC556

• BC559

• 2N3906

• 2SA1015

2N4402 Transistor Specifications

Parameter	Specification
Manufacturer	ON Semiconductor (ONSEMI)
Brand	onsemi
Product Category	Bipolar Transistors – BJT
Product Type	BJTs – Bipolar Transistors
Subcategory	Transistors
Transistor Polarity	PNP
Configuration	Single
Technology	Silicon (Si)
Mounting Style	Through Hole
Package / Case	TO-92-3
Maximum DC Collector Current	600 mA
Continuous Collector Current	600 mA
Collector-Emitter Voltage (VCEO)	40 V
Collector-Base Voltage (VCBO)	40 V
Emitter-Base Voltage (VEBO)	5 V
Collector-Emitter Saturation Voltage	750 mV
Power Dissipation (Pd)	625 mW
DC Current Gain (hFE Min)	30 @ 1 mA, 50 @ 10 mA, 50 @ 150 mA, 20 @ 500 mA
DC Current Gain (hFE Max)	150
Minimum Operating Temperature	−55 °C
Maximum Operating Temperature	+150 °C
RoHS	No
Height	5.33 mm
Length	5.2 mm
Width	4.19 mm
Unit Weight	0.00709 oz

2N4402 Electrical Characteristics

2N4402 Transistor Features

• PNP silicon general-purpose transistor

• Designed for small-signal amplification and switching

• Collector current capability up to 600 mA

• Maximum collector-emitter voltage around 40 V

• High DC current gain for efficient signal amplification

• Low saturation voltage for improved switching performance

• Suitable for low-power and medium-current applications

• Fast switching speed for digital and control circuits

• Operates over a wide temperature range

• Commonly available in TO-92 through-hole package

• Reliable performance for consumer and industrial electronics

2N4402 Transistor Working in Circuit

2N4402 as an Arduino-Controlled Switch and Signal Conditioner

In the first circuit, the 2N4402 is used as a low-side switching and buffering transistor controlled by an Arduino digital pin. The Arduino output drives the transistor base through a resistor, allowing the microcontroller to safely control a higher-voltage load powered by a separate 6 V supply. When the Arduino pin goes HIGH, base current flows and the 2N4402 turns ON, allowing collector–emitter current to flow. The resistor network connected to the emitter forms a voltage divider that feeds an analog input (A0), enabling the Arduino to monitor the resulting voltage. Here, the 2N4402 acts as an interface device that isolates the microcontroller from higher voltages while providing both control and feedback.

2N4402 as a Buzzer Driver and Signal Amplifier Stage

In the second diagram, the 2N4402 is part of a multi-stage signal amplification and output driver circuit. An incoming AC signal is first amplified by a 2N2222 transistor, then passed through coupling and timing components. The 2N4402 transistors are configured to further amplify and shape the signal so it can drive a buzzer. In this role, the 2N4402 provides sufficient current gain to power the buzzer without loading the earlier signal stages. The resistors set the operating bias, while capacitors control timing and response. This application shows how the 2N4402 is well suited for small audio or alert circuits where moderate current drive is required.

2N4402 as a Voltage Control and Regulation Driver

In the third circuit, the 2N4402 functions as a control transistor within a voltage regulation and charging system. It works alongside a reference device (LM431) and a power MOSFET to regulate output current and voltage. The LM431 senses the output level and adjusts the base drive of the 2N4402 accordingly. As the 2N4402 conducts more or less current, it controls the gate of the MOSFET, which in turn regulates the charging current. In this configuration, the 2N4402 is not switching a load directly but acting as an error amplifier and driver, translating small reference changes into controlled power regulation.

Wide Applications

• General-purpose low-power switching in digital and logic control circuits

• Arduino and microcontroller interfacing for driving relays, LEDs, and small loads

• Signal amplification stages in audio, alarm, and buzzer circuits

• Driver transistor for buzzers, speakers, and small electromagnetic devices

• Voltage level shifting and signal buffering between different circuit sections

• Current amplification in sensor conditioning circuits

• Control and feedback element in voltage regulation and charging circuits

• Pulse and timing circuits when combined with RC networks

• Low-side switching in battery-powered and portable electronics

• Educational and prototyping circuits for learning BJT operation

2N4402 Mechanical Dimensions

Advantages & Limitations

2N4402 Advantages

• Simple and easy to use general-purpose NPN transistor

• Low cost and widely available

• Good current gain suitable for small-signal amplification

• Can handle moderate collector current for its package size

• Fast switching performance for digital and logic circuits

• Compatible with common microcontroller output voltages

• Suitable for both switching and amplification applications

• Reliable operation in low- to medium-power designs

2N4402 Limitations

• Limited power dissipation compared to power transistors

• Not suitable for high-voltage applications

• Collector current capability is lower than power BJTs

• Requires proper base current limiting to avoid damage

• Gain varies with temperature and operating conditions

• Not ideal for high-frequency RF applications

• Heat dissipation is restricted by small package size

Manufacturer

On Semiconductor (onsemi) is a global leader in intelligent power and sensing technologies, known for its strong capabilities in designing and manufacturing high-reliability semiconductor solutions. The company specializes in power management, discrete devices, analog, mixed-signal, and sensor technologies that serve automotive, industrial, consumer, and communications markets. Onsemi is recognized for its robust manufacturing infrastructure, long-term product support, and strict quality and reliability standards, including automotive-grade qualifications. Its broad portfolio and focus on energy efficiency enable customers to build scalable, cost-effective, and durable electronic systems for demanding applications.