BU508AF High-Voltage NPN Transistor

Overview

The BU508AF is a high-voltage, high-speed switching NPN transistor housed in a fully isolated SOT199 package. This component is specifically designed for demanding applications requiring robust performance under high-voltage conditions. Its primary application is in horizontal deflection circuits of color television receivers, though its versatile characteristics make it suitable for other high-voltage switching applications as well.

The BU508AF features excellent switching characteristics, high voltage capability, and reliable performance in high-stress environments. The fully isolated package ensures enhanced thermal and electrical performance, making it a preferred choice for designers working with high-voltage circuits.

Features

• High Voltage Capability: Designed to handle high-voltage applications with ease.
• High-Speed Switching: Optimized for fast switching performance, making it ideal for deflection circuits.
• Fully Isolated Package (SOT199): Provides excellent thermal and electrical isolation, improving reliability.
• Robust Construction: Built to withstand high-stress conditions in demanding applications.
• Low Saturation Voltage: Ensures efficient operation with minimal power loss.
• High Current Handling: Capable of managing significant current loads in switching applications.

Applications

The BU508AF is primarily used in high-voltage switching applications, with its most common use being in television receivers. Below are some of its key applications:

• Horizontal Deflection Circuits: The primary application in color television receivers, where high-voltage switching is critical.
• CRT Displays: Used in cathode-ray tube displays for deflection and high-voltage regulation.
• Power Supplies: Suitable for high-voltage power supply circuits requiring fast switching.
• Industrial Equipment: Employed in industrial systems where high-voltage switching is necessary.
• Electronic Ballasts: Used in lighting systems for efficient high-voltage switching.

Electrical Characteristics

The following table summarizes the key electrical characteristics of the BU508AF 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)
• Total Power Dissipation (P_tot): 100W (at 25°C)
• Operating Junction Temperature (T_j): -55°C to +150°C

Typical Electrical Characteristics (T_amb = 25°C unless specified)

• DC Current Gain (h_FE): 8 to 40 (at I_C = 2A, V_CE = 5V)
• Collector-Emitter Saturation Voltage (V_CE(sat)): 1.5V (max) at I_C = 4A, I_B = 1A
• Base-Emitter Saturation Voltage (V_BE(sat)): 2.5V (max) at I_C = 4A, I_B = 1A
• Turn-On Time (t_on): 1.0µs (typical)
• Turn-Off Time (t_off): 4.0µs (typical)
• Collector Cut-Off Current (I_CEO): 1mA (max) at V_CE = 1500V

Package Information

The BU508AF is housed in an SOT199 package, which provides full electrical isolation and excellent thermal performance. Below are the key details of the package:

SOT199 Package Dimensions

• Package Type: SOT199 (fully isolated)
• Mounting Style: Through-hole
• Weight: Approximately 3.5 grams
• Terminal Material: Tin-plated copper
• Thermal Resistance (R_thj-case): 1.25°C/W

Mechanical Specifications

• Lead Pitch: 5.08mm
• Package Length: 20.0mm (max)
• Package Width: 15.0mm (max)
• Package Height: 4.7mm (max)
• Flange Hole Diameter: 3.5mm (for mounting)

Conclusion

The BU508AF is a high-performance NPN transistor designed for high-voltage, high-speed switching applications. Its robust construction, excellent electrical characteristics, and fully isolated SOT199 package make it an ideal choice for demanding environments such as television deflection circuits and industrial power systems. With its high voltage capability and reliable switching performance, the BU508AF continues to be a trusted component in electronic design.