High-Voltage N-Channel Depletion-Mode MOSFET: Microchip LND150K1-G

The Microchip LND150K1-G is a high-voltage N-channel depletion-mode MOSFET designed for a wide range of analog switching, amplification, and current source applications where standard enhancement-mode devices fall short. As a depletion-mode device, it exhibits a unique characteristic: it is normally-on at zero gate-to-source voltage (\(V_{GS} = 0V\)). This fundamental property makes it exceptionally valuable for designing circuits that require a conductive path during startup or in fail-safe conditions.

A key feature of the LND150K1-G is its ability to handle high drain-to-source voltages, rated up to 500V. This high-voltage capability allows it to be used in demanding environments such as offline power supplies, electronic ballasts, and CRT display systems. Furthermore, its very high input impedance, characteristic of all MOSFETs, makes it easy to drive with high-impedance control circuits or voltage sources.

The device is particularly renowned for its use as a constant current source. By tying the gate to the source (\(V_{GS} = 0V\)), the LND150K1-G operates at its saturated drain current, or \(I_{DSS}\). This simple two-terminal configuration provides a stable and predictable current source, ideal for biasing other circuits, driving LEDs, or in linear regulator designs. Its negative temperature coefficient also offers a degree of self-regulation, helping to prevent thermal runaway.

Compared to enhancement-mode MOSFETs or JFETs, the LND150K1-G offers a superior combination of high voltage tolerance and depletion-mode operation in a compact TO-92 package. This makes it an excellent choice for designers looking to simplify circuit architecture in high-voltage applications, reducing the need for additional biasing components that are often required to keep an enhancement-mode device turned on.

ICGOOODFIND: The Microchip LND150K1-G is a highly specialized and robust component that provides a simple, efficient solution for designing high-voltage constant current sources, analog switches, and amplifiers. Its normally-on characteristic is a distinct advantage in specific circuit configurations, offering reliability and performance where other transistors cannot operate effectively.

Keywords: Depletion-Mode MOSFET, High-Voltage, Constant Current Source, Normally-On, Analog Switch