What is the difference between n and p mosfets

It is obvious that the micro controller works with 5 volts output and if you use it directly as a gate voltage, you can not obtain the maximum current from the power source 12 volts above. The second transistor works as a buffer and also isolator for this purpose. And about the diode: this diode is almost always used for loads that contain coils as a motor or a relay.

The purpose is suppression of the backward current made by the coil as an inductor. Let me explain the diode part: let's assume we have a switch connected to a resistor and then an inductor. This means that the inductor searches for a short way to empty it's current and the only way is making a "spark" between heads of the switch. We can see this phenomenon by connecting a DC power to a small DC motor.

We can see although the motor is not working with a high voltage, but by touching its wires with the power cord, "very obvious sparks" are seen.

By replacing the switch with a transistor , the same scenario happens and these continuous sparks lead to the damage to the transistor. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Mosfet usage and P- vs N-channel Ask Question.

Asked 8 years, 2 months ago. Active 1 year, 7 months ago. Viewed 95k times. I'm trying to understand the proper way to use a P-channel or N-channel mosfet in this setting, and came across this sample circuit on google: Why is there another transistor involved the 2N , and why is there a diode across the load?

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When its turned on, the conducting channel if formed by an inversion layer of electrons, which connects 2 n-type places. It lies on N type substrate. When its turned on, the conducting channel is formed by "holes". The depletion region is formed between the n and p type.

It turns ON if there is a sufficiently high negative voltage on the Gate relative to the Source. Only this time, the Source would be too close to the Ground.

You would need to apply a negative voltage relative to the Ground to the Gate to activate it. Functionally you could design your circuit in a way that you could use either of them. If you have an Arduino that runs on 5V and the device you are turning ON also runs on 5V, then it doesn't even matter. But it's standard practice to have a Common Ground between connected devices and modules. To ensure that a MOSFET remains off even if the pin is not connected ex, after Espruino is reset , a pull-down resistor can be placed between gate and source.

MOSFETs only switch current flowing in one direction; they have a diode between source and drain in the other direction in other words, if the drain on an N-channel device falls below the voltage on the source, current will flow from the source to the drain.

This diode, the "body diode" is a consequence of the manufacturing process. This is not to be confused with the diode sometimes placed between the drain and the power supply for the load - this is separate, and should be included when driving an inductive load. They are also easier to manufacture, and thus are available for lower prices with higher performance than p-channel MOSFETs. This means that if you want to use a P-channel mosfet to switch voltages higher than 5V, you'll need another transistor of some sort to turn it on and off.

This is not the threshold voltage - that's the voltage at which it first starts to turn on.