BD237 NPN Transistor Pinout Datasheet

Introduction

The BD237 is a medium-power NPN silicon transistor designed for use in linear amplification, switching, and audio driver circuits. It belongs to the BD23x series (BD233, BD235, BD237), but with a higher voltage rating to support more demanding applications. Packaged in the TO-126 (SOT-32 / JEDEC SOT-32) form factor, BD237 offers compact mounting and compatibility with standard heatsinking for moderate power dissipation.

Engineered with planar epitaxial technology and what ST calls the “Base-Island” layout, the BD237 exhibits improved gain performance and low saturation voltage, making it suitable for circuits that require efficiency and reliable switching margins.Its design is intended to provide a balance of current, voltage, and thermal capability for mid-level power tasks.

BD237 NPN Transistor

In real-world applications, BD237 is often selected when higher voltage headroom is needed relative to its siblings BD233 or BD235. Designers use it in audio amplifier driver stages, push-pull output stages, and general switching circuits where supply rails may reach up to 80 V or more. Its combination of electrical characteristics and mechanical packaging makes it a go-to choice for moderate-power designs that require reliability and versatility.

Pinout of BD237

Key Features

• Higher voltage tolerance compared to lower variants
• Low saturation voltage for efficient switching
• Good gain stability over operating range
• Compact TO-126 package for ease of mounting
• Suitable for complementary pair amplifier designs
• Reliable in both switching and analog circuits

Specifications/Characteristics

• Collector-Base Breakdown Voltage, VCBO = 100 V
• Collector-Emitter Breakdown Voltage, VCEO = 80 V
• Collector-Emitter with base open (sustaining), VCE(sus) = 80 V
• Emitter-Base Breakdown Voltage, VEBO = 5 V
• Collector Current, Continuous IC = 2 A
• Collector Peak (Pulse) Current, ICM = 6 A
• Collector Power Dissipation, Ptot = 25 W (case temperature = 25 °C)
• Maximum Junction Temperature, Tj = 150 °C
• Storage Temperature Range, Tstg = –65 to +150 °C
• Thermal Resistance, Junction-to-Case, θJC = 5.0 °C/W
• Collector Cut-Off Current, ICBO ≤ 0.1 mA (VCB = 100 V, IE = 0)
• Emitter Cut-Off Current, IEBO ≤ 1.0 mA (VEB = 5 V, IC = 0)
• DC Current Gain, hFE(min) = 40 (at IC = 0.15 A, VCE = 2 V)
• DC Current Gain, hFE(min) = 25 (at IC = 1 A, VCE = 2 V)
• Collector-Emitter Saturation Voltage, VCE(sat) = 0.6 V (IC = 1 A, IB = 0.1 A)
• Base-Emitter On Voltage, VBE(on) = 1.3 V (IC = 1 A, VCE = 2 V)
• Transition Frequency, fT = 3 MHz (IC = 0.25 A, VCE = 10 V)

Pin Configuration

Comparison BD233 vs BD235 vs BD237 NPN Transistors

• BD233 is the lowest-voltage member of the series, rated for about 45 V collector-emitter breakdown, making it ideal for low-voltage amplifier and driver circuits. It provides stable performance for general-purpose applications where supply voltages are modest.
• BD235 offers a moderate voltage rating of 60 V, giving it more headroom for circuits running on higher supply rails. It maintains the same current and power handling as BD233, making it a balanced choice between low and high-voltage designs.
• BD237 is the highest-voltage variant, rated up to 80 V collector-emitter and 100 V collector-base, making it suitable for higher-voltage or more demanding applications. It provides extra protection against voltage spikes while keeping gain and switching speed similar to its lower-voltage counterparts.
• All three transistors share the same current (2 A continuous, 6 A peak) and power dissipation (25 W) ratings. They differ mainly in voltage tolerance, allowing designers to select one based on the required supply voltage without changing other circuit parameters.

More Circuit Layouts

Key Applications of BD237 NPN Transistor

• Audio amplifier driver stages
• Push-pull complementary amplifier circuits
• Switch mode and general-purpose switching circuits
• Linear regulators and voltage regulation circuits
• Signal amplification in medium power electronics

PNP Complimentary Transistor

• The PNP complementary counterpart to BD237 is BD238.

Equivalent Transistors of BD237 NPN Transistor

Some possible alternatives or equivalents to BD237 include:

• BD235 (if lower voltage suffices)
• BD233 (for still lower voltage requirement)
• TIP41 / TIP42 (in more general medium-power classes)
• 2N3055 (for significantly higher power applications)
• Other NPN medium-power transistors with similar voltage, current, and power ratings

(Pin configuration of some transistors mentioned here may different from BD237).

Datasheet of BD237 NPN Transistor

Click the following Button below to download the datasheet of BD237 Transistor :

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