Electronics > Beginners
Help Reading JFET Datasheets
(1/2) > >>
eev_carl:
Hi,

I was comparing these two JFETs and was wondering if I was reading their data sheets correctly.

The 2N4392 JFET has a bunch of tr parameters on the order of 5 ns.  The J211 has a transconductance value of 12000 uS.  Are these the same parameters and units (siemens)?

Also, if there is in fact a such a large difference, what does that mean for applications?  (Why choose one over the other?)

Thanks,
Carl

___
2N4392 datasheet : https://www.mouser.com/datasheet/2/68/2n4391-4393-53044.pdf

J211 data sheet : http://interfet.com/datasheet/J210/
eev_carl:
I found another datasheet that has the ns under turn on parameters, so it must be nanoseconds.  I was confused b/c I don't see the transconductance listed on all the datasheets.
Benta:
Yeah, watch the units. There's a major difference between S and s.
Ian.M:
small s is S.I. unit of time (seconds)
big S is S.I. unit of conductance (1/ohms)

S.I. prefixes are used with both in the normal way.

Centralsemi describe the 2N4392 as a analog switching or chopper JFET, so dont bother giving a mutual conductance for it as they don't expect it to be used in its linear region.

David Hess:

--- Quote from: Ian.M on September 07, 2018, 02:54:49 pm ---small s is S.I. unit of time (seconds)
big S is S.I. unit of conductance (1/ohms)
--- End quote ---

If only there was some unambiguous legacy unit for Siemens which would avoid confusion with seconds, samples, and whatever else might use S which itself is easily confused with 5.  Maybe it could even be mnemonic.


--- Quote ---Centralsemi describe the 2N4392 as a analog switching or chopper JFET, so dont bother giving a mutual conductance for it as they don't expect it to be used in its linear region.
--- End quote ---

Exactly, annoyingly as it is, JFET specifications are generally only given in relation to the intended application.  Some of the other specifications can be calculated but some would need to be measured.
Navigation
Message Index
Next page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod