P Channel Mosfet Power Switch Circuit

A circuit for a typical high side switch using a p channel mosfet is shown in fig.

P channel mosfet power switch circuit.

The current necessary for the relay coil is too high for an i o pin but the coil needs 5v to work. During switching a mosfet s source voltage must remain fixed as any variation will modulate the gate and thus adversely affect performance. N channel mosfet characteristics and working. Mosfets are voltage controlled devices.

If you are new and unaware about the working of a n channel mosfet check out this article. In this project we will go over how to connect an p channel mosfet to a circuit for it to function as an electronic switch. We require only few components. A 12v dc supply is connected to the gate of the mosfet through a push button switch.

Mosfets like bjts can function as electronic switches. An excellent use for p channel is in a circuit where your load s voltage is the same as your logic s voltage levels. The input opto coupler and q1 operate the same as fig. Notice the similarities and differences between figs.

The circuit implementation is simple. For example if you re trying to turn on a 5 volt relay with an arduino. In order to operate a mosfet as a switch it must be operated in cut off and linear or triode region. This switch will operate on the positive side of a power supply with a negative common.

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. 2 shows how to use a p channel irf9630 mosfet to switch the positive side of the power supply to the light bulbs acting as a load. Firsly in fig 4 6 13 the resistor r4 whose purpose is to discharge any remaining potential on the gate at switch off is now connected to the positive supply rail instead of to ground. Mosfet as a switch.

2 p channel opto isolated mosfet switching circuit using irf9630 fig. This is for use with 5 volt micro controllers such as arduino. This tutorial will explore the use of a p channel and n channel mosfets as a power switch and general transistor theory. There are a variety of configurations for driving the two mosfets with many different applications.

Although unlike bjts mosfets are turned on not by current but by voltage. To turn on the n channel mosfet requires a positive gate source voltage whereas the p channel mosfet requires a negative gate source potential. We will understand the operation of a mosfet as a switch by considering a simple example circuit. This is a simple circuit where a n channel enhancement mode mosfet will turn on or off a light.

Assume the device is initially off.