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MOSFET question Answered

Greetings everyone,

I've been trying to learn how to use MOSFETs lately, and I've reached a confusing speed bump.  My main objective for a first project will be to simply use it as a switch, but I'd like to really learn them and not just mimic others' work.  The MOSFETs I have are mostly IRF740, IRF540, and IRF240.  

Are 'Enhancement' and 'Depletion' modes of MOSFET operation, or see they separate components?  In other words, can I use any MOSFET in either enhancement or depletion mode?

My brain and I thank you!


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5 years ago

this may be helpful:


The transistors you mention are all enhancement MOSFETs. That means the conductivity can be enhanced when applying a gate voltage.
The source pin is the common pin for drain and gate with the lowest voltage on it. The drain is sitting at a higher voltage. With a gate-to-source voltage of 0V, the FET is not conducting. Conductivity can be enhanced by raising the gate voltage to more positive values.

A depletion mode transistor is conducting the most when the gate-source voltage is 0V. By applying V_GS some charge region in the FET is depleted and the transistor conducts less.

I hope this helps you and your brain a bit.