BF259 Silicon Planar Transistor

Overview

The BF259 is a silicon planar PNP transistor designed for high-voltage applications, particularly in television and monitor deflection circuits. It belongs to the BF25x series, which includes the BF257 and BF258, each tailored for specific voltage and current requirements. The BF259 is optimized for reliable performance in demanding environments, offering robust electrical characteristics and thermal stability.

This transistor is housed in a TO-39 metal package, ensuring excellent heat dissipation and mechanical durability. Its high breakdown voltage and low saturation voltage make it suitable for applications requiring efficient switching and amplification at elevated voltages.

Features

• High Voltage Capability: Designed to handle collector-emitter voltages up to 300V, making it ideal for CRT deflection circuits.
• Low Saturation Voltage: Ensures minimal power loss during switching operations.
• High Current Gain (h_FE): Provides efficient amplification with typical values ranging from 20 to 70.
• Robust Thermal Performance: TO-39 package allows for effective heat dissipation, supporting continuous operation at elevated temperatures.
• Complementary NPN Options: Can be paired with NPN transistors in push-pull configurations for symmetrical circuit designs.
• Wide Operating Temperature Range: Suitable for use in environments ranging from -55°C to +150°C.

Applications

The BF259 is primarily used in high-voltage circuits where reliability and performance are critical. Key application areas include:

• CRT Deflection Systems: Used in horizontal and vertical deflection circuits for televisions and monitors.
• High-Voltage Switching: Suitable for power supply switching and regulation in industrial equipment.
• Audio Amplifiers: Employed in high-voltage audio output stages for public address systems and amplifiers.
• Industrial Control Systems: Used in motor control and relay driving circuits requiring high-voltage tolerance.
• Test and Measurement Equipment: Integrated into high-voltage signal generation and pulse circuits.

Electrical Characteristics

The following tables outline the key electrical parameters of the BF259 transistor under specified test conditions.

Absolute Maximum Ratings

• Collector-Emitter Voltage (V_CEO): 300V
• Collector-Base Voltage (V_CBO): 350V
• Emitter-Base Voltage (V_EBO): 5V
• Collector Current (I_C): 100mA (continuous)
• Total Power Dissipation (P_tot): 8W at 25°C (derated linearly above 25°C)
• Operating and Storage Temperature Range: -55°C to +150°C

Typical Electrical Characteristics (T_A = 25°C unless noted)

• DC Current Gain (h_FE): 20 to 70 at I_C = 10mA, V_CE = 5V
• Collector-Emitter Saturation Voltage (V_CE(sat)): ≤ 0.5V at I_C = 50mA, I_B = 5mA
• Base-Emitter Saturation Voltage (V_BE(sat)): ≤ 1.2V at I_C = 50mA, I_B = 5mA
• Transition Frequency (f_T): 50MHz typical at I_C = 10mA, V_CE = 10V
• Output Capacitance (C_ob): 4pF typical at V_CB = 10V, f = 1MHz

Package Information

The BF259 is available in a TO-39 metal can package, which provides superior thermal and mechanical performance compared to plastic packages. The package dimensions and pin configuration are as follows:

TO-39 Package Dimensions

• Case Material: Metal (typically steel or alloy)
• Weight: Approximately 0.4 grams
• Lead Material: Tinned copper
• Mounting Style: Through-hole
• Pin Configuration:
  • Pin 1: Emitter (E)
  • Pin 2: Base (B)
  • Pin 3: Collector (C)

Thermal Characteristics

• Thermal Resistance, Junction-to-Ambient (R_θJA): 62.5°C/W
• Thermal Resistance, Junction-to-Case (R_θJC): 12.5°C/W

Reliability and Compliance

The BF259 is manufactured using high-quality silicon planar technology, ensuring consistent performance and long-term reliability. It complies with industry standards for electrical and environmental stress, including:

• RoHS compliance (Restriction of Hazardous Substances)
• ESD protection (Electrostatic Discharge) up to 1kV (Human Body Model)

Conclusion

The BF259 is a high-voltage PNP transistor that excels in applications requiring robust performance under demanding conditions. Its combination of high breakdown voltage, low saturation voltage, and reliable thermal characteristics makes it a preferred choice for deflection circuits, power switching, and industrial control systems. The TO-39 package further enhances its suitability for high-reliability applications where heat dissipation and mechanical durability are critical.