what does the diode do in a mosfet?

[BrendanP]

Im looking at the schematic on the data sheet for a IRF540N mosfet. It shows what looks like a zener diode inside the package. What does it do? Is it to absorb back EMF in induction loads?

 

 

[Michael 2727]

Here are some notes from IRF<A href='http://www.irf.com/technical-info/appnotes/an-936.pdf' Target=_Blank>External Web Link</a>
For heavy work don't rely on the internal diode alone, use a 1N4004 or 1N5408 or heavy duty (TO-220 package) high speed diode.
A few cents to a dollar or two on a diode could save you 5 to 10 bucks replacing a dead MOSFET.

 

[BeanieBots]

Wasn't aware the IRF540 had an internal diode, but even if it does, what Michael 2727 says is good advice.

 

[c6jones720]

In a lot of Mosfets the diode is parasitic and comes about as a by product of the silicon manufacturing process.

 

[BrendanP]

Thanks guys, thanks Michael for finding the link and posting it.

The data sheet is great Michael, a big thank you.

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Edited by - BrendanP on 04/09/2007 09:33:38