JFET reversibility question

T

Trent

New Member

• Sep 17, 2010

• #1

Hello,

I have a p-channel JFET, NTE 326, and I'm wondering if the source and drain are reversible on this particular FET? I've seen datasheets for this and they give the pinout ID, but they don't say if it is reversible nor do they give a symbol indicating this. Does anybody know?

Thanks

 

crutschow

Well-Known Member

Most Helpful Member

• Sep 17, 2010

• #2

Normally FETs have the substrate connected to the source terminal. Thus the drain and source are not interchangeable.

 

T

Trent

New Member

• Sep 17, 2010

• #3

Murphy's Law is alive and well.
Yesterday I built the circuit with the p-channel FETs wired the same as the n-channel, with the source being negative, and today I found a diagram saying electron flow is opposite in the p-channel FETs.
Assuming these FETs are the non-reversible kind, how possible is it that I damaged the FETs?

PS. I'm operating in the ohmic region.

Thanks

 

Last edited: Sep 17, 2010

audioguru

Well-Known Member

Most Helpful Member

• Sep 18, 2010

• #4

NTE buys ordinary FETs, marks up the price and marks their own part number on them.
The NTE326 is a P-channel Jfet. They do not say which "real" Jfet is is.

Some if not all Jfets are made symmetrically so the source and drain can be swapped and it works the same.

 

crutschow

Well-Known Member

Most Helpful Member

• Sep 18, 2010

• #5

As Uncle $scrooge says it may be bidirectional. Tying the substrate to the source terminal is done in MOSFETS, but I forgot that JFETS typically have the source and drain connect directly to the substrate and thus the source and drain can often be interchanged.

 

T

Trent

New Member

• Sep 18, 2010

• #6

Thanks guys