[sdiy] NC pin on ICs

[David G. Dixon]

Thanks to all for your interesting and varied responses.  I'm not sure I
have a clearer idea now than I did before, but at least I know not to assume
that NC strictly means "not connected" in every case.

In fact, I misread the HFA3128 datasheet, and it is only available in
surface mount, so I will probably not be using it.  I was considering it
because it is the only chip with five PNP's on a single substrate, and
therefore would have been nice for a current-sourcing expo converter with
four matched outputs.  Indeed, it may be worthwhile to develop a mock DIP of
this little beastie with pin connectors and a little bitty pcb.  

The problem arose from the fact that I was trying to lay out a board where I
could have used either the HFA3128 or five discrete TO-92 PNP's, all with
common emitters, and four with common bases.  The way I lay out circuits (by
hand on Excel with strict 0.1" spacing all around), I was going to have to
bring the emitter trace out from under the chip through the NC gap.  I would
have simply cut off the NC pin, I think.