N Channel Mosfet High Side Switch Circuit

To switch v with a n channel mosfet use a n channel mosfet with drain connected to v and the load connected to source.

N channel mosfet high side switch circuit.

The n channel mosfet of a buck converter is a high side switch. There are a variety of configurations for driving the two mosfets with many different applications. For an n channel mosfet the source connects to ground and the drain connects to the negative side of the load. The main problem in using an n channel mosfet in a high side switch is that in order for the mosfet to switch off once it has been switched on is that the voltage on the gate terminal of the mosfet must be made higher than the supply voltage.

Used as a high side switch a p channel mosfet in a totem pole arrangement with an n channel mosfet will simulate a high current high power cmos complementary mos arrangement. Conversely if you are doing a low side switch pulls the load low or to ground an n channel device would be chosen. Drive circuits for the high side switches are called high side drivers and are more complicated than low side drivers because of the required voltage translation to the supply and because it is more difficult to turn off a floating switch. Consider the source as the input and the drain as the output.

Then the p channel mosfet is used to switch the positive supply to the motor for forward direction high side switching while the n channel mosfet is used to switch the negative supply to the motor for reverse direction low side switching. If you are doing a high side switch pulls the load high or positive to turn it on a p channel device would be chosen. In order to do this the gate voltage must be magnified in some way. The opposite of the low side switch is the high side switch.

In the low side configuration the load is connected between the drain and v while the source. While you can use a jfet for this circuit an enhancement mode mosfet works better. The n channel high side switch. This transistor connects between v and the load.