onsemi BU407

Overview

BU407 from ON Semiconductor is a high-voltage NPN epitaxial silicon power transistor designed for horizontal deflection output stages in CRT displays. It delivers 7 A DC collector current, withstands 330 V collector-base voltage, and operates with 60 W collector dissipation at TC = 25°C. Its TO-220 package supports robust thermal management in switching applications.

For engineers reviewing the BU407 datasheet, pinout, applications, or equivalent options, key selection criteria include safe operating area (SOA) compliance at 150 V/5 A, turn-off time of 0.75 µs under specified drive conditions, saturation voltage of 1 V at IC = 5 A/IB = 0.5 A, and junction temperature rating up to 150°C.

Technical Context

The BU407 employs an epitaxial base structure optimized for high-voltage switching with low storage time and controlled minority-carrier lifetime. Its SOA is defined up to 10 ms pulse width with derating above 25°C case temperature, supporting reliable operation in flyback and line-output circuits.

It features a fixed three-terminal configuration (Base–Collector–Emitter) with no integrated protection diodes or bias networks. Electrical behavior is characterized under DC and pulsed conditions per JEDEC JESD22-A108, with fT = 10 MHz measured at VCE = 10 V and IC = 0.5 A.

Key Specifications

Pinout & Package

BU407 is housed in a TO-220 package with standard leadframe geometry, non-isolated tab (collector-connected), and through-hole mounting. Thermal resistance from junction-to-case is 2.08°C/W (typical), requiring mechanical fastening and thermal compound for heatsink attachment.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage NPN switching transistor applications.

Compared with BU406 and 2SC5027, the BU407 offers superior voltage headroom (330 V VCBO) and higher continuous current (7 A), making it the preferred choice for legacy CRT horizontal output and high-stress flyback applications where SOA and thermal robustness are critical.

Availability

BU407 is available at Aetrix Electronics and suitable for horizontal deflection circuits, flyback power supplies, and electronic ballast designs requiring stable component supply and long-lifecycle support.

Supply support for BU407 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

ON Semiconductor is a global semiconductor manufacturer specializing in power management, analog, sensors, and discrete devices for automotive, industrial, and consumer markets.

The BU407 belongs to ON Semiconductor's high-voltage bipolar transistor product line, engineered specifically for reliability-critical horizontal deflection and medium-power switching applications in legacy display and power conversion systems.

FAQ

What is the maximum collector-emitter voltage rating for BU407?

The BU407 has a VCEO rating of 150 V, meaning it can safely block up to 150 V between collector and emitter when fully turned off. This rating is verified under standard test conditions (TC = 25°C) and defines the upper limit for linear and switching operation in circuits such as CRT horizontal output stages. Exceeding this voltage risks avalanche breakdown and permanent device failure. Always consult the BU407 datasheet for SOA curves and transient voltage limits.

Does BU407 have an insulated tab in its TO-220 package?

No, the BU407 uses a standard non-insulated TO-220 package where the metal tab is internally connected to the collector terminal. Electrical isolation from the heatsink must be achieved using an insulating washer and shoulder washer kit. This differs from variants like TO-220F or TO-220AB with built-in insulation. Confirm mechanical layout and creepage requirements before mounting BU407 in high-voltage applications.

What is the typical turn-off time for BU407 under standard test conditions?

The BU407 exhibits a typical turn-off time (tOFF) of 0.75 µs when tested at IC = 5 A and IB = 0.5 A. This value reflects the combined delay and storage time under defined drive conditions and is critical for ensuring clean commutation in 15.625 kHz horizontal deflection circuits. Actual tOFF may vary with base drive strength, temperature, and load inductance, so system-level validation is recommended for timing-critical designs using BU407.

Can BU407 replace BU407H in all applications?

The BU407 and BU407H share identical absolute maximum ratings and package, but differ in guaranteed performance: BU407H specifies tighter tOFF (0.4 µs vs. 0.75 µs) and higher ICP (10 A pulse) with improved consistency. BU407H is intended for higher-reliability or faster-switching implementations. Substituting BU407 for BU407H is acceptable only if the application tolerates longer turn-off time and does not require guaranteed 10 A pulse current capability.

What thermal resistance values apply to BU407 in TO-220 package?

The BU407 has a typical junction-to-case thermal resistance (RθJC) of 2.08°C/W. When mounted on a heatsink with thermal compound and proper torque, total thermal resistance (junction-to-ambient) depends on heatsink efficiency and airflow. For continuous 60 W dissipation, case temperature must remain ≤ 25°C - requiring substantial heatsinking. Derating begins above 25°C per the published power derating curve in the BU407 datasheet.