BC637 NPN Transistor Pinout Datasheet

Introduction

The BC637 is a general-purpose NPN bipolar junction transistor (BJT), widely used in medium-power amplification and switching applications. It belongs to the BC63x transistor family, which includes BC635 and BC639, designed primarily for audio frequency amplifier stages and signal driver circuits. With a collector current capacity of up to 1A and a collector-emitter voltage rating of 60V, the BC637 provides a reliable and efficient solution for circuits requiring moderate voltage and current levels.

Built using silicon epitaxial planar technology, the BC637 ensures excellent gain linearity, fast switching speed, and stable thermal behavior. Its TO-92 package makes it ideal for both compact electronic designs and educational circuits. The transistor offers a balanced combination of high DC current gain (hFE) and low saturation voltage (VCEsat), which helps in efficient current amplification with minimal power loss.

BC637 NPN Transistor

The BC637 is commonly used in audio amplifier drivers, signal preamplifiers, voltage regulators, and relay control circuits. Due to its robust electrical properties and low cost, it has become a popular choice among engineers, hobbyists, and circuit designers who need a dependable transistor for small to medium signal processing tasks.

BC637 Pinout

Pin Configuration

Key Features

• NPN silicon planar transistor for medium-power applications
• Excellent linear amplification and signal handling
• High DC current gain with low saturation voltage
• Reliable operation with good thermal stability
• Suitable for audio frequency and switching circuits
• Compact and widely compatible TO-92 package

Characteristics

• Collector-Base Voltage (VCBO): 80V
• Collector-Emitter Voltage (VCEO): 60V
• Emitter-Base Voltage (VEBO): 5V
• Collector Current (IC): 1A maximum
• Power Dissipation (Ptot): 1.25W
• DC Current Gain (hFE): 40 to 160
• Transition Frequency (fT): 100MHz typical
• Operating and Storage Junction Temperature: –55°C to +150°C
• Package Type: TO-92

Comparison Summary: BC635 vs BC637 vs BC639

• The BC635 has the lowest voltage rating (45V) and is typically used in low-power amplification and signal driver circuits.
• The BC637 offers higher voltage (60V) and current capacity (1A), making it suitable for medium-power audio amplifier and switching applications.
• The BC639 is the strongest among the three, with even higher voltage capability (80V) and superior power dissipation, designed for high-voltage or demanding signal circuits.

• BC635 → Low-power and low-voltage circuits
• BC637 → Medium-power, balanced performance
• BC639 → High-voltage, high-performance applications

More Circuit Layouts

Key Applications of BC637 Transistor

• Audio amplifier driver and output stages
• Voltage and current amplification circuits
• Medium-power switching circuits
• Relay and solenoid drivers
• Motor control and sensor interface circuits
• General-purpose electronic and educational projects

PNP Complementary Transistor

• The PNP complementary transistor of BC637 is BC638. These two devices are often used together in push-pull amplifier configurations, offering symmetrical performance for both halves of the audio waveform.

Equivalent of BC637 NPN Transistor

• BC635
• BC639
• 2N2222
• BD135
• MPS2222A
• 2N3904
• S8050

Always verify the pin configuration and ratings before substitution.

Datasheet of BC637 NPN Transistor

Click the following Button to download the datasheet of BC637 Transistor :

More projects, You may like:

• Video Transmitter DIY Homemade FM Radio Transmitter
• Adjustable Power Supply DIY Battery Charger
• 12V-220V 500 Watt inverter DIY Homemade
• MPPT Solar Charge Controller DIY Homemade
• DIY LA4440 bass amplifier homemade

For more project and circuit diagrams, you can go through the Schematics in the main menu where you can find many interesting projects and circuit diagrams like audio amplifier circuits, voltage booster circuit, battery charger circuit and timer circuits etc., which are all beginner circuit projects. Feel free to check them out!

Thank you for visiting the article.