[sdiy] S D Mosfet swap

[René Schmitz]

At 23:11 03.11.02 -0600, Paul Schreiber wrote:
>Generally speaking, no. Unlike a JFET, the MOSFETs have something called a 'body diode' from D to
>S. Thankfully, the manufacturers started showing this on the data sheet drawings :)
>
>Paul S.

But the general case doesn't help here. If the device has a seperate substrate/bulk terminal 
you can choose which terminal will be the drain and which is the source. The one you tie the 
bulk to becomes the source. (determining the direction of the body diode.) In the 4007 the 
substrates end at the Vss and Vdd terminals. So as long as the body diode doesn't become 
forward biassed drain and source can be interchanged. (Infact you can even do this for mosfets 
with the body diode already tied to the source, as long as you don't exceed 0.6V in reverse 
direction. This is why this filter works at all!)
I'd recommend ignoring the pin numbers on the drawing, and try the intended pin functions. Then 
you'll find out if it makes a difference.

Cheers, 
 René



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