MOSFET Control

mosfetThe MOSFET is a field effect transistor voltage controlled transistor and like all the other transistors, the MOSFET is used to amplify the current flowing through. It has three areas of operation: blocked (it passes no current), linear (amplifies the current flowing through proportional manner) and saturated (allows maximum current). In vehicular applications, it is mainly used to power electronics in blocked and saturated states. Then it should be seen as a switch that allows current to pass or not.

It is important to know that when it’s saturated, the MOSFET has an internal resistor. This resistance, although very small (of the order of 1mΩ to 150mΩ), limits current and dissipates heat. If the current becomes too high, it is possible that the temperature increases enough to damage the MOSFET. In recent years, the MOSFET has experienced many improvements with the addition of integrated electronic components.

Such as:

  • The control of MOSFET directly by the microcontroller (0V, 3.3V, 5V) without complex external circuit.
  • Protection against high temperatures.
  • Protection against short-circuits.
  • A load current reading by a proportional current sensor.
  • Diagnostic functions to determine the status of the MOSFET.

Zone Technologies uses MOSFETs mainly to control various accessories installed on the vehicle. The MOSFET is protected against short circuits and if loads are too big, then it is possible to use as fuses or circuit breakers.

Guillaume Leclerc, eng.
Project Manager