delorie.com/archives/browse.cgi   search  
Mail Archives: geda-user/2014/02/10/13:00:40

X-Authentication-Warning: delorie.com: mail set sender to geda-user-bounces using -f
X-Recipient: geda-user AT delorie DOT com
X-Virus-Scanned: amavisd-new at neurotica.com
X-NSA-prism-xkeyscore: I do not want to be surveilled
Message-ID: <52F9139E.4030403@neurotica.com>
Date: Mon, 10 Feb 2014 12:59:58 -0500
From: Dave McGuire <mcguire AT neurotica DOT com>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0
MIME-Version: 1.0
To: geda-user AT delorie DOT com
Subject: Re: [geda-user] How to identify nc pads in tsym files
References: <CAD2FfiGyyumxy0CVdw7sCVwxhThJ4dGha3jLLyLobwNKP1xcXg AT mail DOT gmail DOT com> <alpine DOT LRH DOT 2 DOT 01 DOT 1402100805360 DOT 15107 AT homer02 DOT u DOT washington DOT edu>
In-Reply-To: <alpine.LRH.2.01.1402100805360.15107@homer02.u.washington.edu>
X-Enigmail-Version: 1.6
Reply-To: geda-user AT delorie DOT com

On 02/10/2014 11:11 AM, Frank Miles wrote:
>> I'm dealing with a QFN16 package where the middle "pin" is used as a
>> signal. The only way to get to the middle pin is a via (not sure this
>> is a good idea...), or I can trivially use an nc pin on the package to
>> get to the center.
> 
> 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 - so the pin is more of a "don't YOU
> connect to this" than a truly "Not connected (anywhere)".

  I got screwed by exactly this a few weeks ago, with a 4-20mA pressure
sensor.  The assembly guys wired the harnesses with the "NC" wire
connected to ground.  The sensors just plain DID NOT WORK in that
configuration.  I had 'em clip and terminate that wire, and they all
came up just fine.

                  -Dave

-- 
Dave McGuire, AK4HZ
New Kensington, PA

- Raw text -


  webmaster     delorie software   privacy  
  Copyright © 2019   by DJ Delorie     Updated Jul 2019