BF420 Pinout, Equivalent, Application, Datasheet

The BF420 is an NPN high-voltage transistor designed for reliable amplification and switching in high-voltage circuits. This article explains the BF420 pinout, electrical characteristics, working principle, applications, and suitable alternatives for high-voltage and signal-processing designs.

Introduction

The BF420 is a high-voltage NPN bipolar junction transistor optimized for medium-frequency amplification and switching. With a very high voltage rating and compact TO-92 package, it is widely used in power supply circuits, high-voltage signal amplifiers, and driver stages.

Pin Configuration / Pinout of BF420 Transistor

Understanding the BF420 Pinout Configuration

The BF420 is available in a TO-92 package with the following pin arrangement:

Correct identification of the BF420 pinout (B-C-E) is critical for safe operation in high-voltage applications.

Note: DATASHEET DOWNLOAD button is provided end of this article.

BF420 Key Features

• NPN high-voltage bipolar transistor
• Very high collector-emitter voltage capability
• Suitable for medium-frequency amplification
• Compact TO-92 package
• Stable electrical performance
• Reliable operation in high-voltage environments

BF420 Specifications/Characteristics

• Collector-Emitter Voltage (Vceo): 300V
• Collector-Base Voltage (Vcbo): 300V
• Emitter-Base Voltage (Vebo): 5V
• Collector Current (Ic): 50mA
• Peak Collector Current (Icm): 100mA
• Total Power Dissipation (Ptot): 830mW
• Junction Temperature (Tj): 150°C
• Storage Temperature (Tstg): −65°C to 150°C
• DC Current Gain (hFE): 50
• Transition Frequency (fT): 60MHz

Key Applications of BF420 Transistor

• High-voltage amplifier circuits
• Power supply driver stages
• CRT and display driver circuits
• Switching stages in high-voltage systems
• Signal conditioning in industrial electronics

BF420 Equivalent / Alternatives

(Verify pin compatibility before using substitutions)

Equivalent Transistors:

• BF421
• BF422

Alternative Devices:

• MJE340
• 2SC2310

More Circuit Layouts

Working Principle of BF420

The BF420 works by controlling a larger collector current with a small base current. When the base-emitter junction is forward biased, charge carriers flow from emitter to collector, enabling amplification or switching of high-voltage signals with stability and reliability.

Frequently Asked Questions (FAQ)

Q1: Is BF420 suitable for high-voltage applications?
Yes, BF420 supports up to 300V collector-emitter voltage.

Q2: What package does BF420 use?
BF420 is available in a TO-92 package.

Q3: Can BF420 be used for switching applications?
Yes, it can be used for both amplification and switching.

Q4: What is the maximum collector current of BF420?
The maximum continuous collector current is 50mA.

Conclusion

The BF420 NPN high-voltage transistor offers strong voltage handling, stable performance, and compact packaging. Its suitability for high-voltage amplification and switching makes it a dependable choice for industrial, display, and power electronics applications.

Datasheet of BF420 Transistor

Click the following Button below to download the datasheet of BF420 :

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