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Mail Archives: geda-user/2014/02/11/04:25:27

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Date: Tue, 11 Feb 2014 10:24:34 +0100
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Subject: Re: [geda-user] How to identify nc pads in tsym files
From: Richard Hughes <hughsient AT gmail DOT com>
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On 10 February 2014 15:15, Gabriel Paubert <paubert AT iram DOT es> wrote:
> On this kind of package, typically the center pad is some kind of
> ground/power. It's a bit surprising that you call it "signal", but
> we've seen strange things.

It's a bit of a strange chip:
http://www.mazet.de/en/english-documents/data-sheets/mtcsicf/download

> Otherwise you can always explicitly show these pins on the symbol
> and connect them to the net that goes to the center pad.

Yes, I thought about that, but that means if I upload the symbol then
someone might get confused they *have* to use this pin. Seems a bit of
hack, but it's the favourite so far.

On 10 February 2014 17:11, Frank Miles <fpm AT u DOT washington DOT edu> wrote:
> You have to be careful about 'NC' pins.  Sometimes these are truly not
> connected; but for some chips these are connected to internals in ways
> not fully revealed in the datasheet

Yes, agreed, I've been bitten by this in the past. The datasheet has
an explicit:

"""
The term "nc" means the contact is not connected internally, is not
needed for any electrical function
but important for IC soldering (mechanical function). There is no need
to wire this contact to Ground.
The NC pads on PCB could be used for PCB layout routing.
"""

So I'm fairly confident :)

What I really need is a way of saying "this pin can connect to *any*
net" in the tsym file.

Richard.

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