BU508AX High-Voltage NPN Transistor

Overview

The BU508AX is a high-voltage, high-speed switching NPN transistor housed in a fully isolated SOT399 package. Designed primarily for horizontal deflection circuits in color television receivers, this component offers robust performance in high-voltage applications. Its fully isolated package ensures enhanced thermal and electrical isolation, making it suitable for demanding environments.

The transistor is optimized for fast switching and high-voltage operation, making it ideal for deflection circuits, switch-mode power supplies (SMPS), and other high-voltage applications. Its construction ensures reliability and efficiency, even under strenuous operating conditions.

Features

• High Voltage Capability: Designed to handle high-voltage applications, making it suitable for CRT deflection circuits.
• Fast Switching Speed: Optimized for high-speed switching, reducing power losses in switching applications.
• Fully Isolated Package (SOT399): Provides excellent thermal and electrical isolation, improving reliability in high-stress environments.
• High Current Handling: Capable of managing significant current loads, ensuring stable operation in deflection circuits.
• Low Saturation Voltage: Minimizes power dissipation during conduction, improving efficiency.
• Robust Construction: Designed for long-term reliability in demanding applications such as television receivers and monitors.

Applications

The BU508AX is widely used in applications requiring high-voltage switching and fast response times. Key applications include:

• Horizontal Deflection Circuits: Primarily used in color television receivers and CRT monitors for horizontal deflection.
• Switch-Mode Power Supplies (SMPS): Suitable for high-voltage switching in power supply units.
• Electronic Ballasts: Used in lighting applications requiring high-voltage switching.
• High-Voltage Inverters: Ideal for circuits converting DC to high-voltage AC.
• CRT Display Systems: Ensures reliable performance in cathode-ray tube-based display systems.

Electrical Characteristics

The following table summarizes the key electrical characteristics of the BU508AX under typical operating conditions:

Absolute Maximum Ratings

• Collector-Emitter Voltage (V_CEO): 1500V
• Collector-Base Voltage (V_CBO): 1700V
• Emitter-Base Voltage (V_EBO): 7V
• Collector Current (I_C): 8A (continuous), 15A (peak)
• Base Current (I_B): 4A
• Total Power Dissipation (P_tot): 100W (at T_C = 25°C)
• Operating Junction Temperature (T_j): -55°C to +150°C
• Storage Temperature (T_stg): -55°C to +150°C

Thermal Characteristics

• Thermal Resistance, Junction-to-Case (R_th(j-c)): 1.25°C/W
• Thermal Resistance, Junction-to-Ambient (R_th(j-a)): 62.5°C/W

Dynamic Characteristics

• Turn-On Time (t_on): 1.0µs (typical)
• Turn-Off Time (t_off): 3.5µs (typical)
• Fall Time (t_f): 1.0µs (typical)
• Collector-Emitter Saturation Voltage (V_CE(sat)): 2.5V (max) at I_C = 4A, I_B = 1A

Package Information

The BU508AX is housed in an SOT399 (TO-218) package, which provides excellent thermal and electrical isolation. The package is designed for high-power applications and features a fully insulated construction to prevent short circuits and improve heat dissipation.

Package Dimensions

• Package Type: SOT399 (TO-218)
• Mounting Style: Through-hole
• Weight: Approximately 10g
• Lead Material: Copper alloy
• Isolation Voltage: 2500V (min)

Mechanical Drawing

The package dimensions are as follows (typical values in millimeters):

• Total Height: 16.5mm
• Lead Length: 10mm
• Lead Spacing: 5.45mm (between pins)
• Body Width: 10.4mm
• Body Length: 20.8mm

Conclusion

The BU508AX is a high-performance NPN transistor designed for high-voltage, high-speed switching applications, particularly in horizontal deflection circuits of CRT-based systems. Its robust construction, fast switching characteristics, and fully isolated package make it a reliable choice for demanding electronic applications. With its high current and voltage ratings, the BU508AX ensures efficient operation in television receivers, power supplies, and other high-voltage circuits.