What is 2N3055 NPN Power Transistor? This article will discuss the 2N3055 transistor in detail, including its basic characteristics, pinout, specifications, features, working principles, applications, safe operating practices, equivalent models, and comparisons with similar devices such as the TIP3055.

Catalog

2N3055 Transistor Basic

The 2N3055 NPN Power Transistor by ONSEMI is a well-known silicon bipolar junction transistor designed for high-power and high-current applications. It is widely used in linear power supplies, power amplifiers, motor drivers, and industrial control circuits where reliability and durability are required. Its classic TO-3 (TO-204AA) metal package provides excellent heat dissipation, making it suitable for demanding operating conditions.

The 2N3055G is the Pb-free (RoHS-compliant) version of the 2N3055 and offers the same electrical characteristics and performance, differing only in environmental compliance. Both versions are fully interchangeable in circuit designs.

If you are interested in purchasing the 2N3055 or 2N3055G NPN Power Transistor, feel free to contact us for pricing and availability.

2N3055 Transistor CAD Models

2N3055 Transistor Pinout Details

Alternatives & Equivalent Model

• MJ15003

• MJ15015

• MJ15016

• MJ15024

• MJ21194

• MJ21196

• MJ802

• MJ4502

• 2N3771

• 2N3772

• TIP3055

• BD249

• BD249A

• BD249B

• BD249C

• 2N5885

• 2N5886

• 2N5884

• 2N3055H

2N3055 Transistor Specifications

2N3055 Transistor Features

High Collector Current Capability

The 2N3055 can handle collector currents of up to 15 A, making it suitable for high-current applications such as linear power supplies, audio power amplifiers, motor drivers, and battery chargers. This capability allows the transistor to drive heavy loads reliably without excessive stress when properly heatsinked.

High Power Dissipation

With a maximum power dissipation of around 115 W, the 2N3055 is designed to operate in high-power environments. This feature enables it to manage significant heat generated during operation, especially in linear regulator and amplifier circuits where continuous power handling is required.

Robust TO-3 Metal Package

The classic TO-3 (TO-204AA) metal can package provides excellent mechanical strength and thermal performance. The metal case allows efficient heat transfer to a heatsink, improving reliability and extending the transistor’s operational life under demanding conditions.

Moderate Voltage Ratings

The transistor supports a collector-emitter voltage (VCEO) of 60 V and a collector-base voltage (VCBO) of 100 V. These ratings make the 2N3055 ideal for low- to medium-voltage power applications commonly found in industrial and audio systems.

Low-Frequency Power Operation

With a transition frequency (fT) of approximately 2.5 MHz, the 2N3055 is optimized for low-frequency and DC applications rather than high-speed switching. This makes it particularly effective in linear amplifiers and power regulation circuits.

Stable DC Current Gain

The device offers a minimum DC current gain (hFE) of about 20, providing stable amplification characteristics. This predictable gain simplifies circuit design and ensures consistent performance across operating conditions.

Wide Operating Temperature Range

The 2N3055 operates over a wide temperature range from −65 °C to +150 °C, allowing it to function reliably in harsh industrial and outdoor environments when properly cooled.

2N3055 Transistor Working in Circuit

2N3055 Transistor as a Simple Zener-Based Voltage Regulator

In the first diagram, the 2N3055 is used as a series pass transistor to regulate voltage. A Zener diode provides a fixed reference voltage (12 V) at the transistor’s base through a resistor. Because the base–emitter junction of the 2N3055 drops about 0.6–0.7 V, the output voltage at the emitter becomes slightly lower than the Zener voltage (around 11.3–11.4 V). When the load current changes, the 2N3055 adjusts its conduction automatically, allowing more or less current to flow while maintaining a nearly constant output voltage. This circuit demonstrates how the 2N3055 handles higher current than a Zener diode alone, improving load-driving capability.

2N3055 Transistor as a Linear Regulated Power Supply

In the second diagram, the 2N3055 operates in a complete linear power supply. An AC transformer steps down the mains voltage, which is then converted to DC by a bridge rectifier. A large electrolytic capacitor smooths the rectified DC to reduce ripple. The Zener diode again sets a stable reference voltage for the base of the 2N3055 through a resistor. Acting as a pass element, the 2N3055 supplies high current to the load while maintaining a regulated output of about 12 V. An additional small capacitor at the output improves stability and noise suppression. This circuit highlights the 2N3055’s strength in delivering high current with good thermal handling, making it suitable for bench power supplies and industrial DC sources.

2N3055 Transistor Applications

• Linear regulated power supplies

• Series pass transistor in voltage regulators

• Audio power amplifier output stages

• Bench power supply designs

• High-current DC power supplies

• Battery chargers

• DC motor drivers

• Relay and solenoid drivers

• Industrial control circuits

• Inverter and UPS output stages

• Power amplifiers for low-frequency signals

• Current booster circuits

• Electronic load and current control circuits

• Voltage stabilizer circuits

2N3055 Safely Operation

To operate the 2N3055 safely, proper heat management is essential. Because this transistor can dissipate high power, it must be mounted on a suitable heatsink using thermal grease, and electrical insulation should be applied if the collector-connected case may contact grounded metal. Inadequate cooling can quickly lead to thermal runaway and device failure.

The voltage and current limits must always be respected during operation. Exceeding the maximum collector–emitter voltage or collector current can permanently damage the transistor. Designers should also ensure the 2N3055 operates within its safe operating area (SOA), especially in linear applications where both voltage and current are present simultaneously.

Proper base drive control is equally important. Limiting the base current with an appropriate resistor prevents excessive drive that could overheat the device. In power supply and amplifier circuits, adding protective components such as fuses or current-limiting resistors further improves reliability and long-term stability.