BU407 NPN Power Transistor (150V-7A)

BU407 – NPN Power Transistor

(High-voltage NPN Bipolar Junction Transistor – BJT)

General Description

The BU407 is an NPN silicon power transistor designed for high-voltage, high-speed switching applications, such as horizontal deflection circuits in CRT displays, inverters, power supplies, and motor drivers. It can handle high collector voltages and moderate current, with decent switching speed.

Key Specifications

Package – TO-220 Pinout

       ________
      |        |
Base | 1      | Collector (Tab)
      | 2      |
Emitter | 3   |
      --------

Features

• High collector voltage handling (up to 150V)
• Moderate current (up to 4A)
• Fast switching capability
• Rugged TO-220 package with good thermal dissipation
• Suitable for flyback converters and CRT deflection

Typical Applications

• CRT monitor horizontal deflection
• High-voltage switching
• Inverter circuits
• Motor driver circuits
• Flyback converters

Usage Notes

• Requires proper base drive for fast switching (often via a resistor and diode for turn-off speed).
• Use a heatsink when operating at high current or continuous power.
• Add a snubber circuit (RC or diode) to protect against voltage spikes in inductive loads.

Advantages

• Reliable and robust for high-voltage work
• Still available from multiple manufacturers
• Handles decent power and voltage