BD239 NPN Transistor Pinout Datasheet

Introduction

The BD239 is a silicon epitaxial-base NPN power transistor, commonly used in general-purpose switching and linear amplifier circuits. It’s known for its robustness in power applications and its capacity to handle moderate current and voltage stresses, making it suitable for hobbyist and industrial designs alike. The transistor is packaged in TO-220 plastic form, giving a sturdy mechanical footprint and good capability for heatsinking.

One of the strengths of BD239 is its balanced performance in gain, saturation voltage, and voltage tolerance, which allows it to be used in diverse circuits—from audio drivers to switching regulators. Because it is part of a family (BD239, BD241, BD243), designers often pick it when they want to step up from lower-voltage devices but avoid going to heavy-duty power transistors.

BD239 NPN Transistor

Additionally, BD239 often appears in designs that require a complementary PNP device (e.g. BD240 series) to form push-pull stages or symmetrical amplifier outputs. Its moderate specs also make it effective in driver stages, preamplifiers, or as an interface transistor between control logic and larger output devices.

Pinout of BD239

Key Features

• Reliable NPN power transistor for combined switching and amplification use
• Good thermal stability when mounted on heatsink
• Balanced tradeoff of voltage, current, and gain for medium-power use
• Suitable for complementary amplifier configurations
• Durable mechanical construction for repeated use
• Compatible with many standard transistor designs

Specifications/Characteristics

• Collector-Emitter Voltage, VCEO (base open) = 100 V
• Collector-Base Voltage, VCBO (emitter open) = 115 V
• Emitter-Base Voltage, VEBO = 5 V
• Collector Current, IC (continuous) = 2 A
• Collector Current, ICM (peak / pulsed) = 4 A
• Collector Power Dissipation, Ptot = 30 W (at case temperature = 25 °C)
• Junction Temperature, Tj = 150 °C
• Storage Temperature Range, Tstg = –65 to +150 °C
• Collector–Emitter Saturation Voltage, VCE(sat) = 0.7 V (IC = 1 A)
• Base-Emitter On Voltage, VBE(on) = 1.3 V (IC = 1 A, VCE = 4 V)
• Collector Cut-Off Current, ICBO ≤ 0.2 mA (VCE = 100 V)
• Emitter Cut-Off Current, IEBO ≤ 1 mA (VEB = 5 V)
• DC Current Gain, hFE (min) = 40 (IC = 0.2 A, VCE = 4 V)
• DC Current Gain (lower) = 15 (IC = 1 A, VCE = 4 V)

Pin Configuration

Comparison BD239 vs BD241 vs BD243

• BD239 sits in this series as a moderate-voltage transistor with a collector-emitter rating of 100 V and collector-base rating of 115 V, providing good headroom for higher-voltage amplifier and switching applications.
• BD241 typically offers a lower voltage rating (often around 80 V or 100 V depending on variant), making it more suited to circuits with moderate supply voltages and less voltage stress.
• BD243 represents the higher-voltage side of the series; its variants are rated for up to 100 V or more between collector-emitter (and even higher in collector-base for some versions), making BD243 more robust in circuits with high voltage or transient demands.
• All three transistors share a similar current capability (around 2 A continuous) and are often used in similar amplifier or switching roles; the primary difference is their voltage tolerance, making you select BD239 for more robust voltage environments, BD241 for moderate, and BD243 when maximum voltage margin is needed.

More Circuit Layouts

Key Applications of BD239 NPN Transistor

• Audio amplifier stages and drivers
• Push-pull amplifier output stages (with complement)
• Switch-mode and general-purpose switching circuits
• Power supply regulators and control circuits
• Signal interfacing and medium power transistor roles

PNP Complimentary Transistor

• The PNP complementary counterpart to BD239 is BD240.

Equivalent Transistors of BD239 NPN Transistor

Some alternatives or equivalents to BD239 include:

• BD241 (another NPN in same family)
• BD243 (higher-voltage variant)
• 2N3055 (for higher power applications)
• 2N2222 / BD135 etc (for lower power alternatives)
• Other NPN power transistors in TO-220 form with similar voltage/current ratings

(Pin configuration of some transistors mentioned here may different from BD239).

Datasheet of BD239 NPN Transistor

Click the following Button to download the datasheet of BD239 Transistor :

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