BSS138

The BSS138 is a N-channel MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) manufactured by ON Semiconductor. It is designed for low-voltage applications and is particularly popular in switching and amplification circuits. Here’s a detailed description of its features and specifications:

Physical Characteristics:

• Package Type: The BSS138 is typically available in a TO-92 package, which is a cylindrical plastic package with three leads. This makes it suitable for through-hole mounting on printed circuit boards (PCBs).
• Dimensions: The TO-92 package has a standard size, making it easy to handle and integrate into various electronic designs.

Electrical Specifications:

• Drain-Source Voltage (V_DS): The BSS138 can handle a maximum drain-source voltage of 50V, making it suitable for a wide range of applications.
• Gate-Source Voltage (V_GS): The maximum gate-source voltage is ±20V, allowing for flexibility in control signal levels.
• Continuous Drain Current (I_D): The device can conduct a continuous drain current of up to 220mA at a temperature of 25°C, which is adequate for many low-power applications.
• R_DS(on): The on-resistance (R_DS(on)) is typically around 3.5 ohms at a gate-source voltage of 10V, which ensures efficient operation with minimal power loss during switching.

Performance Characteristics:

• Threshold Voltage (V_GS(th)): The threshold voltage, which is the minimum gate-source voltage required to turn the MOSFET on, is typically between 0.8V and 1.5V. This low threshold allows for easy interfacing with low-voltage logic levels.
• Switching Speed: The BSS138 features fast switching capabilities, making it suitable for high-speed applications. The rise and fall times are typically in the nanosecond range, which is beneficial for digital circuits.

Applications:

• Level Shifting: The BSS138 is often used in level shifting applications, where it can convert signals between different voltage levels, such as interfacing 5V logic with 3.3V systems.
• Switching Circuits: It is commonly employed in low-power switching applications, such as driving small loads, controlling relays, or in power management circuits.
• Signal Amplification: The device can also be used in analog applications for signal amplification due to its high input impedance and low output capacitance.

Thermal Characteristics:

• Junction-to-ambient Thermal Resistance (θJA): The thermal resistance is typically around 250°C/W, which indicates how well the device can dissipate heat. Proper thermal management is essential to ensure reliable operation, especially under high load conditions.

Conclusion:

The BSS138 from ON Semiconductor is a versatile and reliable N-channel MOSFET that is well-suited for a variety of low-voltage applications. Its combination of low on-resistance, fast switching speed, and ability to handle moderate current makes it a popular choice among engineers and hobbyists alike. Whether used in switching, amplification, or level shifting, the BSS138 provides a robust solution for modern electronic designs.