P Channel Mosfet Power Switch Circuit

The circuit implementation is simple.

P channel mosfet power switch circuit.

We require only few components. In order to operate a mosfet as a switch it must be operated in cut off and linear or triode region. There are a variety of configurations for driving the two mosfets with many different applications. For example if you re trying to turn on a 5 volt relay with an arduino.

Mosfet as a switch. 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. To turn on the n channel mosfet requires a positive gate source voltage whereas the p channel mosfet requires a negative gate source potential. This is a simple circuit where a n channel enhancement mode mosfet will turn on or off a light.

If you are new and unaware about the working of a n channel mosfet check out this article. Mosfet as a switch. A circuit for a typical high side switch using a p channel mosfet is shown in fig. 2 p channel opto isolated mosfet switching circuit using irf9630 fig.

We will understand the operation of a mosfet as a switch by considering a simple example circuit. The type of p channel mosfet we will use is the enhancement type mosfet the most commonly used type of mosfet. This is for use with 5 volt micro controllers such as arduino. N channel mosfet characteristics and working.

Mosfets are voltage controlled devices. In this case use a p channel mosfet to turn the relay on from the arduino s i o pin. Assume the device is initially off. A 12v dc supply is connected to the gate of the mosfet through a push button switch.

Notice the similarities and differences between figs. During switching a mosfet s source voltage must remain fixed as any variation will modulate the gate and thus adversely affect performance. An excellent use for p channel is in a circuit where your load s voltage is the same as your logic s voltage levels. 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. The input opto coupler and q1 operate the same as fig. 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. This switch will operate on the positive side of a power supply with a negative common.

The current necessary for the relay coil is too high for an i o pin but the coil needs 5v to work.