BD438 PNP Transistor Pinout Datasheet

Introduction

The BD438 is a medium-power PNP silicon transistor intended for linear amplification and switching applications. It is part of the BD43x complementary transistor family from ST / ON Semiconductor, serving as the PNP counterpart to the NPN device BD437.

This transistor is packaged in a SOT-32 / TO-126 plastic case, which supports modest heatsinking and ensures mechanical stability in power circuits. The BD438 is designed with parameters to match its NPN partner in push-pull amplifier designs, enabling symmetric response in complementary output stages.

BD438 PNP Transistor

In practical design use, BD438 is commonly found in audio output stages, switching circuits, and power supply regulator circuits, especially in configurations where a PNP transistor is needed for the negative or “top” side of push-pull designs.

Pinout of BD438

Key Features

• PNP polarity suitable for high-side or negative conduction circuits
• Complementary pairing with BD437 to enable push-pull amplifier designs
• Plastic package allowing moderate thermal management
• Balanced design for both switching and linear operation
• Stable performance in medium-power audio and control circuits
• ROHS-compliant and Pb-free versions available

Specifications/Characteristics

• Collector-Emitter Voltage, VCEO = –45 V (max)
• Collector-Base Voltage, VCBO = –45 V (max)
• Emitter-Base Breakdown Voltage, VEBO = –5 V
• Collector Current, Continuous IC = –4 A
• Total Power Dissipation, PD = 36 W (at case temperature = 25 °C)
• Maximum Junction Temperature, Tj = 150 °C
• Storage Temperature Range, Tstg = –55 to +150 °C
• Collector-Emitter Saturation Voltage, VCE(sat) = –0.6 V (IC = –2 A, IB = –0.2 A)
• Base-Emitter On Voltage, VBE(on) = –1.1 V (for a typical operating point)
• Transition Frequency, fT = 3 MHz

Pin Configuration

Comparison BD438 (PNP) vs BD437 (NPN Complementary)

• BD438 is a PNP transistor designed to conduct in the negative half cycles or to serve as the “top” side device in push-pull amplifier configurations. It mirrors the performance of its NPN counterpart but with reversed polarity.
• BD437 is the NPN counterpart, conducting during the positive half cycles or serving as the “bottom” or lower-side device in complementary output stages.
• When used together in complementary designs, BD438 and BD437 are matched in ratings—current, power dissipation, gain, and frequency—so that amplifier or switching systems can achieve symmetric performance across both signal polarities, minimizing distortion and imbalance.

More Circuit Layouts

Key Applications of BD438 PNP Transistor

• Push-pull complementary amplifier output stages
• Audio amplifier driver and output circuits
• High-side switching in power supplies and driver circuits
• Voltage regulators and analog control circuits needing PNP stages
• General-purpose PNP transistor usage in medium-power electronic systems

NPN Complimentary Transistor

• The complementary NPN transistor for BD438 is BD437.

Equivalent Transistors of BD438 PNP Transistor

Some possible alternative or equivalent PNP transistors to BD438 include:

• BD436 (lower-voltage PNP in the same family)
• BD434 (lower-voltage PNP sibling)
• General-purpose PNP power transistors like TIP32C, MJE2955 (if voltage/current specs align)
• Other PNP transistors in similar current class (4 A) with ~40–50 V rating

Datasheet of BD438 PNP Transistor

Click the following Button to download the datasheet of BD438 Transistor :

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