N Channel Mosfet High Side Switch Circuit

In order to do this the gate voltage must be magnified in some way.

N channel mosfet high side switch circuit.

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. To switch v with a n channel mosfet use a n channel mosfet with drain connected to v and the load connected to source. 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. The n channel mosfet of a buck converter is a high side switch.

For an n channel mosfet the source connects to ground and the drain connects to the negative side of the load. Conversely if you are doing a low side switch pulls the load low or to ground an n channel device would be chosen. Consider the source as the input and the drain as the output. The opposite of the low side switch is the high side switch.

There s a catch with this arrangement though the mosfet switches on based on the vgs threshold being reached and the source voltage in this arrangement changes between off 0v and on vin. There are a variety of configurations for driving the two mosfets with many different applications. While you can use a jfet for this circuit an enhancement mode mosfet works better. Although the p channel mosfet cannot complement the n channel in both on resistance and capacitance simultaneously such combinations as the low threshold p channel tp0610 and the n channel 2n7000.

The n channel high side switch. In the low side configuration the load is connected between the drain and v while the source. 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. 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.