BD433 NPN Transistor Pinout Datasheet

Introduction

The BD433 is a silicon epitaxial-base NPN power transistor designed for medium-power linear and switching applications. It is packaged in a JEDEC SOT-32 / TO-126 plastic outline, making it suitable for mounting on small heatsinks while still offering moderate power capability. It is commonly used in audio output stages, radio amplifiers, and general-purpose power circuits.

Because it belongs to a family where there are PNP complements (e.g. BD434) and variants such as BD435, BD437, it is often employed in push-pull amplifier stages or complementary amplifier designs. Its moderate voltage and current ratings make it a good choice in systems where efficiency, reliability, and symmetry are needed.

BD433 NPN Transistor

In practical use, the BD433 is particularly favored for car-radio output stages and other audio amplification roles, due to its balance of gain, power, and thermal stability. Designers also use it in switching circuits, driver circuits, or as the NPN side of complementary output stages.

Pinout of BD433

Key Features

• Medium-power NPN transistor for linear and switching use
• Compatible for complementary pairing with PNP transistor types
• Balanced performance suitable for audio and driver roles
• Plastic package offering manageable thermal characteristics
• Robust in diverse circuit environments
• Good reproducibility and availability in the BD43x series

Specifications/Characteristics

• Collector-Base Breakdown Voltage (VCBO) = 22 V
• Collector-Emitter Breakdown Voltage (VCEO) = 22 V
• Collector-Emitter Sustaining Voltage (VCES) = 22 V
• Emitter-Base Breakdown Voltage (VEBO) = 5 V
• Continuous Collector Current (IC) = 4 A
• Peak (Pulse) Collector Current (ICM) = 7 A
• Total Power Dissipation (Ptot) = 36 W (at case temperature = 25 °C)
• Maximum Junction Temperature (Tj) = 150 °C
• Storage Temperature Range (Tstg) = –65 to +150 °C
• Transition Frequency (fT) = 3 MHz

Pin Configuration

Comparison BD433 vs BD434 Complementary

• BD433 is an NPN transistor with moderate voltage, current, and power ratings, used in linear and switching roles. Its strength lies in its suitability for audio output stages and car-radio amplifier roles.
• BD434, as the complementary PNP transistor, is matched to the BD433 in terms of current, gain, and power, enabling push-pull amplifier designs where the NPN handles positive half cycles and the PNP handles negative cycles.
• Because BD433 and BD434 are complementary pair, designers use them together in symmetrical amplifier outputs, benefiting from matched performance in gain, saturation, and thermal behavior.

More Circuit Layouts

Key Applications of BD433 NPN Transistor

• Audio amplifier output stages
• Car-radio power amplifiers
• Push-pull complementary amplifier circuits
• Medium-power switching circuits
• Driver stages in power electronics
• General-purpose amplifier and switching roles

PNP Complimentary Transistor

• The PNP complementary device to BD433 is BD434

Equivalent Transistors of BD433 NPN Transistor

Possible alternatives or equivalent transistors (or in similar class) include:

• BD435 and BD437 (other NPN types in the same family)
• Other NPN medium-power transistors with comparable voltage/current specs
• 2N3055 (for heavier power designs)
• TIP41 / TIP31 in lower power applications
• Other NPN power transistors in TO-126 / TO-220 style with matching ratings

(Pin configuration of some transistors mentioned here may different from BD433).

Datasheet of BD433 NPN Transistor

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