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From:	Kai-Martin Knaak <kmk AT familieknaak DOT de>
Subject:	Re: [geda-user] gschem: assigning multiple pcb pad numbers to one schematic pin?
Date:	Wed, 29 Jul 2015 01:45:36 +0200
Lines:	29
Message-ID:	<mp9471$dbg$1@ger.gmane.org>
References:	<55B7849E DOT 6070401 AT envinsci DOT co DOT uk>
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Matt Rhys-Roberts (matt.rhys-
roberts AT envinsci DOT co DOT uk) [via geda-user-
Ht4Cp5ncgjRBDgjK7y7TUQ AT public DOT gmane DOT org] wrote:

> The default SOT223 footprint (3 legs and a large pad) has pads
> numbered 1~4, but the device I want to use it with only has 3
> different pins effectively. I don't want to get into editing the FP
> it if I don't have to.
> 
> My device has pins numbered 1,2,3 and the pad is connected to pin 2.

This is the common set-up for transistors and regulators. I have yet 
to get my hands on a device that does not have the middle pin 
connected to the cooling pad.

 
> Can I modify the schematic symbol so that pin 2 can be connected to
> pads 2 and 4 somehow?

I went for the complementary solution and designed my SOT223 footprint 
with only pin numbers 1, 2 and 3. The large section that solders to 
the cooling pad also gets pin number 2. For better heat dispersion I 
added another big pad on the bottom side. It connects to the top with 
a couple of thru hole pins. The thru hole pins and the big bottom bad 
get also pin number 2. 

This footprint was able to dissipate heat quite efficiently.

---<)kaimartin(>---

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