BD139 NPN Transistor Datasheet Pinout

Introduction

The BD139 is a popular and cost-effective NPN power transistor widely used in a variety of electronic circuits. Due to its robust features, it’s an ideal component for both educational projects and commercial electronics. Its high collector current of up to 1.5A allows it to drive numerous high-current components, such as high-power LEDs, high-current relays, and motors, making it highly versatile for switching applications.

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With a high collector-emitter and collector-base voltage of 80V, the BD139 can easily operate in circuits running under 80V, ensuring its durability and reliability. Its impressive collector power dissipation of 12.5 watts makes it a strong candidate for audio amplifier circuits, where it can efficiently handle and dissipate heat. Additionally, the transistor’s low saturation voltage of just 0.5V ensures minimal power loss when used as a switch, further enhancing its efficiency.

BD139 NPN Transistor

BD139 Pinout

BD139 NPN Transistor Key Features

The BD139 is a medium-power NPN bipolar junction transistor (BJT). Part of the popular BD series, it’s widely recognized for its robust performance and versatile applications. Its combination of high current handling, voltage ratings, and amplification capabilities makes it a cornerstone component in many electronic designs.

• NPN Polarity: As an NPN transistor, it allows a large current to flow from the collector to the emitter when a small positive voltage is applied to its base. This is the fundamental mode of operation that enables it to function as both a switch and an amplifier.
• High Collector Current (IC​): The BD139 can handle a continuous collector current of up to 1.5A. This is a significant feature that distinguishes it from small-signal transistors and allows it to drive more powerful loads like motors, relays, and high-power LEDs.
• High Voltage Ratings: It has a high collector-emitter voltage (VCE​) of 80V and a collector-base voltage (VCB​) of 80V. These ratings ensure its suitability for a wide range of medium-voltage circuits.
• High Power Dissipation: With a maximum collector power dissipation of 12.5 watts, the BD139 is designed to handle medium-power applications without overheating, especially when a suitable heatsink is used.
• DC Current Gain (hFE​): The transistor has a DC current gain ranging from 40 to 160. This high gain allows for effective signal amplification, making it ideal for audio amplifiers and other signal-processing circuits.
• Low Noise and Distortion: The BD139 is known for its low noise and distortion characteristics. This makes it an excellent choice for audio amplification, as it ensures a high-fidelity output signal.
• Transition Frequency (fT​): With a transition frequency of up to 190 MHz, the BD139 can be used in some RF (Radio Frequency) applications, such as low-power oscillators.
• Compact Package: The BD139 is typically available in a TO-126 or SOT-32 plastic package, which is easy to mount on a PCB and facilitates heat dissipation.

BD139 Transistor Specifications/Characteristics

More Circuit Layouts

Key Applications of BD139 NPN Transistor

The BD139 is a versatile NPN transistor from the BD13x series, commonly used in medium-power applications. Its key features enable it to function effectively as both a switch and an amplifier.

• Audio Amplifiers: The BD139 is frequently used in the driver and output stages of audio amplifiers, where its robust gain and current handling capability allow it to amplify audio signals efficiently. It is often paired with its complementary PNP transistor, the BD140, to create Class B push-pull amplifier circuits for high-fidelity sound.
• Switching Loads under 1.5A: With a maximum continuous collector current of 1.5A, the BD139 can act as an effective electronic switch. It is capable of controlling a variety of medium-power loads, such as relays, solenoids, and high-power LEDs, making it a staple in control circuits.
• Battery Chargers: The BD139 is often integrated into the control or regulation circuits of battery chargers. It helps manage the current flow to the battery, ensuring a stable and safe charging process.
• Power Supplies: It is used in power supply circuits, particularly in linear voltage regulators, where it acts as a pass transistor to maintain a stable output voltage by dissipating excess power.
• Motor Driver: The BD139 can be used to control the speed and direction of small to medium-sized DC motors, making it a key component in motor driver circuits for robotics and other electromechanical projects.
• Darlington Pair: When combined with another transistor in a Darlington pair configuration, the BD139 can achieve extremely high current gain. This is useful for applications where a very small input current needs to control a much larger load.
• Inverters and Converters: The BD139 is also used in low-to-medium power inverter and converter circuits to switch DC current at specific frequencies, converting DC to AC or changing the voltage level.

PNP Complimentary Transistor

PNP Complementary of BD139 Transistor is BD140.

Equivalent Transistors of BD139

BD230, 2SC5171S , BD349, and BD379
(The pinout for certain transistors can vary from that of the BD139).

Datasheet of BD139 NPN Transistor

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