P Channel Mosfet Power Switch Circuit

N channel mosfet characteristics and working.

P channel mosfet power switch circuit.

This is a simple circuit where a n channel enhancement mode mosfet will turn on or off a light. In this case use a p channel mosfet to turn the relay on from the arduino s i o pin. The input opto coupler and q1 operate the same as fig. Mosfets are voltage controlled devices.

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. An excellent use for p channel is in a circuit where your load s voltage is the same as your logic s voltage levels. A circuit for a typical high side switch using a p channel mosfet is shown in fig. During switching a mosfet s source voltage must remain fixed as any variation will modulate the gate and thus adversely affect performance.

This switch will operate on the positive side of a power supply with a negative common. The circuit implementation is simple. In order to operate a mosfet as a switch it must be operated in cut off and linear or triode region. The current necessary for the relay coil is too high for an i o pin but the coil needs 5v to work.

The type of p channel mosfet we will use is the enhancement type mosfet the most commonly used type of mosfet. We will understand the operation of a mosfet as a switch by considering a simple example circuit. Notice the similarities and differences between figs. This tutorial will explore the use of a p channel and n channel mosfets as a power switch and general transistor theory.

2 p channel opto isolated mosfet switching circuit using irf9630 fig. A 12v dc supply is connected to the gate of the mosfet through a push button switch. For example if you re trying to turn on a 5 volt relay with an arduino. If you are new and unaware about the working of a n channel mosfet check out this article.

Mosfets like bjts can function as electronic switches. Mosfet as a switch. To turn on the n channel mosfet requires a positive gate source voltage whereas the p channel mosfet requires a negative gate source potential. Mosfet as a switch.

Although unlike bjts mosfets are turned on not by current but by voltage. 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. Assume the device is initially off. 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.

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.