BC108 NPN Transistor Technical Summary

Overview

The BC108 is a silicon NPN transistor housed in a hermetically sealed TO-18 metal package, designed for general-purpose amplification and switching applications. This component is known for its reliability, robust construction, and consistent performance across a wide range of operating conditions. The BC108 is part of a family of transistors (including BC107 and BC109) that share similar characteristics but differ in voltage and current ratings.

With its high voltage tolerance and moderate current handling capabilities, the BC108 is suitable for use in audio amplifiers, signal processing circuits, and low-power switching applications. Its hermetically sealed package ensures protection against environmental factors, making it ideal for use in harsh conditions.

Features

• Silicon NPN Construction: Provides reliable performance with low leakage currents.
• Hermetically Sealed TO-18 Package: Ensures durability and protection against moisture and contaminants.
• Screening Options Available: Allows for enhanced quality control and performance verification.
• High Voltage Ratings:
  • Collector-Base Voltage (VCBO): 50V
  • Collector-Emitter Voltage (VCEO): 30V
  • Emitter-Base Voltage (VEBO): 6V
• Moderate Current Handling:
  • Continuous Collector Current (IC): 100mA
  • Peak Collector Current (ICM): 200mA
• Wide Operating Temperature Range: -65°C to +175°C, suitable for extreme environments.
• Low Power Dissipation: 300mW at 25°C ambient temperature.

Applications

The BC108 is versatile and finds use in a variety of electronic circuits, including:

• Audio Amplifiers: Used in pre-amplification and low-power output stages due to its low noise and high gain characteristics.
• Signal Processing: Ideal for small-signal amplification in radio frequency (RF) and intermediate frequency (IF) stages.
• Switching Circuits: Suitable for low-power switching applications in logic circuits and relay drivers.
• Oscillators and Timers: Used in waveform generation and timing circuits due to its stable performance.
• Industrial Controls: Employed in sensor interfaces and control systems where reliability is critical.

Electrical Characteristics

The following table summarizes the key electrical characteristics of the BC108 transistor at 25°C unless otherwise specified:

Absolute Maximum Ratings

• Collector-Base Voltage (VCBO): 50V
• Collector-Emitter Voltage (VCEO): 30V
• Emitter-Base Voltage (VEBO): 6V
• Continuous Collector Current (IC): 100mA
• Peak Collector Current (ICM): 200mA
• Total Power Dissipation (Ptot): 300mW at 25°C
• Operating Temperature Range (Tamb): -65°C to +175°C
• Storage Temperature Range (Tstg): -65°C to +175°C

Typical Performance Characteristics

• DC Current Gain (hFE): Typically ranges from 110 to 450, depending on operating conditions.
• Transition Frequency (fT): Approximately 150MHz, making it suitable for RF applications.
• Collector-Emitter Saturation Voltage (VCE(sat)): Typically 0.2V at IC = 10mA, IB = 1mA.
• Noise Figure: Low noise performance, ideal for audio and sensitive signal amplification.

Package Information

The BC108 is housed in a TO-18 metal can package, which provides excellent thermal performance and mechanical durability. Below are the key mechanical specifications:

TO-18 Package Dimensions

• Package Type: TO-18 (Metal Can)
• Pin Configuration:
  • Pin 1: Emitter
  • Pin 2: Base
  • Pin 3: Collector
• Dimensions:
  • Diameter: 5.08mm (0.200 inches)
  • Height: 4.7mm (0.185 inches)
  • Lead Spacing: 2.54mm (0.100 inches) nominal
  • Lead Diameter: 0.48mm (0.019 inches)

Mechanical Drawing

The TO-18 package features a standardized pinout with the emitter, base, and collector arranged in a triangular configuration. The metal can provides shielding against electromagnetic interference (EMI) and enhances heat dissipation.

Conclusion

The BC108 NPN transistor is a reliable and versatile component suitable for a wide range of low-power amplification and switching applications. Its hermetically sealed TO-18 package ensures long-term stability and performance in demanding environments. With its robust electrical characteristics and compact form factor, the BC108 remains a popular choice among designers for both industrial and consumer electronics.