[sdiy] unused pins ?

[Magnus Danielson]

From: Mountain Man <mtman at cloud9.net>
Subject: [sdiy] unused pins ?
Date: Sat, 07 Apr 2001 10:53:19 -0400

> Hi folks,

Hi there...

> I'm breadboarding my first "non-pcb" circuit and I'm
> wondering what to do with the pins that are unconnected?  Specifically,
> the S/H from tomg's sbm doesn't seem to use the offsets on the TL071,
> but I'd like a general answer to this question :)  Do I leave them
> unconnected?

Yeap. You should.

>  Connect to ground?  Does it depend on the particular
> circuit?

It most particularly depend on the chip. For logic gates and
especially CMOS chips you should wire all inputs to either high or
low, they should never be allowed to be floating. For OPs you should
check the datasheet carefully, but for things like offset and
compensation inputs it is most commonly so that you may leave them
really unconnected.

Except for logic chips, you should find hints in the datasheets, for
logic chips you may have to look in the familly description documents
in order to find the necessary sentence.

Leaving floating CMOS inputs around can be a HUGE misstake!!!
I guess Harry could toss in some nice story on it, I don't have one
that springs to mind at this moment...

Cheers,
Magnus