Pnp Transistor High Side Switch

A transistor has a 3 sandwich.

Pnp transistor high side switch. Notice that the emitter is connected to the positive voltage. Npn high side switch r2 works as a pullup resistor to keep the base positive when the npn is off so that the pnp is off too. I normally would switch the high side second diagram but i guess the first method should also work although it would dissipate more power in the transistor and not have. I saw a suggestion on using a pnp for switching a load on the low side with the collector grounded emitter following the input first diagram as opposed to the high side.

Figure 8 2 shows a circuit using a pnp transistor as a high side switch. This transistor connects between v and the load. The circuit above is called a low side switch because the switch our transistor is on the low ground side of the circuit. Transistor as switch.

When npn turns on it sinks current through r1 r2 and this creates a voltage drop to the base of pnp which turns it on. Transistor is 3 terminal electronic semiconductor component device. Transistor name meaning lies in its own working. Npn transistor as a switch.

Some of the applications use a power transistor as switching device at that time it may necessary to use another signal level transistor to drive the high power transistor. Similar to the npn circuit the base is our input and the emitter is tied to a constant voltage. Trans istor transistor the prefix trans tells about signal transfer from low resistance to high resistance part and istor means solid physical structure having property of resistance. The opposite of the low side switch is the high side switch.

We ll need a more complex circuit to implement a practical high side power on switch. Which means that pnp transistor shown in the first image will always be on regardless of the i o pin state. The application of an pnp transistor is to work as a high side switch. Alternatively we can use a pnp transistor to create a high side switch.

The first important thing to bear in mind to use a current limiting resistor at base. Both npn and pnp transistors can be used as switches. Using pnp transistors is essentially the same as npn transistors except the polarities are reversed. Higher base currents will damage a bjt.

The real switch is still the pnp transistor on the right. It has three terminals named as base emitter and collector. Based on the voltage applied at the base terminal of a transistor switching operation is. This time however the emitter is tied high.

Because of how transistors work these can be a little more difficult to use in an arduino or raspberry pi circuit.