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Old 12th Jan 2017, 12:05 am   #14
WaveyDipole
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Join Date: Mar 2013
Location: Leicester, UK
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Default Re: 2N3819 Mosfet

Interesting conundrum! If you take it that the Vishay sheet correctly shows the 'Top View', then the pin numbers match up with the Fairchild sheet, but the pin assignments are reversed. If you assume its an error and the Vishay sheet shows the bottom view, then the pin assignments now match up but the pin numbers are reversed!

For my 2p worth, I would observe that if, as Wikipedia seems to suggest (https://en.wikipedia.org/wiki/TO-92), the standard pin numbering sequence on a TO-92 package is shown correctly on the 3D Fairchild illustration, then the Vishay sheet must indeed be showing the top view. This would seem to suggest that one of them has the pin assignments reversed. But which one is correct? Well one possible thing to do might be to compare spec sheets from other manufacturers:

http://www.onsemi.com/pub_link/Collateral/2N3819-D.PDF
http://www2.eng.cam.ac.uk/~dmh/ptialcd/jfet/2N3819.pdf

But just when you think you have the answer, you come across this one:

https://www.centralsemi.com/get_docu..._id=2n3819.PDF

In short, op, you are not going mad! There does seem to be an inconsistency in pin assignments between manufacturers. They all number the pins on the TO-92 package the same way, but some have drain on pin 1, others have source on pin 1. It is just as well, I guess, that it does not really matter, although a bit of consistency would have been nice!

Last edited by WaveyDipole; 12th Jan 2017 at 12:32 am.
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