BS108 N-Channel Enhancement Mode MOSFET

Overview

The BS108 is an N-channel enhancement mode MOSFET designed for low-power switching applications. This component is widely used in digital and analog circuits due to its high input impedance, fast switching speeds, and compatibility with TTL and CMOS logic levels. The BS108 is particularly suitable for applications requiring efficient switching with minimal drive requirements.

Features

• N-Channel Enhancement Mode: Provides efficient switching with positive gate voltage.
• Low Threshold Voltage: Ensures compatibility with TTL and CMOS logic levels.
• High Input Impedance: Reduces drive current requirements, making it ideal for low-power applications.
• Fast Switching Speeds: Enables high-frequency operation in switching circuits.
• Low On-Resistance: Minimizes power dissipation during conduction.
• Compact Package Options: Available in TO-92 and SOT-23 packages for versatile PCB integration.

Applications

The BS108 is commonly used in a variety of electronic circuits, including:

• Logic Level Switching: Interfaces directly with TTL and CMOS logic circuits.
• Signal Switching: Used in analog and digital multiplexers.
• Low-Power Drivers: Drives relays, LEDs, and other low-current loads.
• Voltage Regulation: Employed in low-dropout linear regulators and DC-DC converters.
• Battery-Powered Devices: Ideal for portable electronics due to low power consumption.

Electrical Characteristics

The following table summarizes the key electrical specifications of the BS108 MOSFET:

Absolute Maximum Ratings

• Drain-Source Voltage (V_DS): 100V
• Gate-Source Voltage (V_GS): ±20V
• Drain Current (I_D): 200mA
• Total Power Dissipation (P_tot): 360mW (TO-92 package)
• Operating Temperature Range: -55°C to +150°C

Static Electrical Characteristics

• Threshold Voltage (V_GS(th)): 1.0V to 3.0V (at I_D = 1mA)
• On-Resistance (R_DS(on)): 10Ω (max) at V_GS = 10V, I_D = 50mA
• Gate-Source Leakage Current (I_GSS): ±1nA (max) at V_GS = ±20V

Dynamic Electrical Characteristics

• Input Capacitance (C_iss): 15pF (typ) at V_DS = 25V, V_GS = 0V
• Output Capacitance (C_oss): 5pF (typ) at V_DS = 25V, V_GS = 0V
• Turn-On Delay Time (t_d(on)): 10ns (typ) at V_DD = 50V, R_L = 100Ω
• Turn-Off Delay Time (t_d(off)): 20ns (typ) at V_DD = 50V, R_L = 100Ω

Package Information

The BS108 is available in two standard package options:

TO-92 Package

• Package Type: Through-hole, 3-pin
• Pin Configuration:
  • Pin 1: Gate (G)
  • Pin 2: Drain (D)
  • Pin 3: Source (S)
• Dimensions: 4.7mm x 3.7mm x 4.9mm (typical)
• Thermal Resistance (R_θJA): 357°C/W (typical)

SOT-23 Package

• Package Type: Surface-mount, 3-pin
• Pin Configuration:
  • Pin 1: Gate (G)
  • Pin 2: Source (S)
  • Pin 3: Drain (D)
• Dimensions: 2.9mm x 1.3mm x 0.95mm (typical)
• Thermal Resistance (R_θJA): 250°C/W (typical)

Conclusion

The BS108 N-channel enhancement mode MOSFET is a versatile and reliable component for low-power switching applications. Its compatibility with TTL and CMOS logic levels, combined with fast switching speeds and low on-resistance, makes it an excellent choice for a wide range of electronic designs. Whether used in logic interfaces, signal switching, or low-power drivers, the BS108 delivers consistent performance in a compact and cost-effective package.