Re: [SI-LIST] : how to combine multi components together with Orcad layout

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From: Jon Keeble (jkeeble@alpha.net.au)
Date: Wed Mar 22 2000 - 20:22:49 PST


Orcad supports a concept of autoplace on a grid.

You could
(1) auto place the ICs on a grid
(2) auto place the bypass caps on another grid of the same dimensions
somewhere else
(3) block move one set of parts over the other set of parts

Orcad also supports the concept of component group.

If you identify the IC and its bypasses as belonging to a group, then all
the parts in the group can be made to
move together.

By the way: there has been some discussion of bypassing recently. You may
want to review the idea of having
a lot of identically valued bypass caps, and you may not need two per chip.

The latest Orcad revision is 9.1, and it fixes a lot of problems in 9.0.

-----Original Message-----
From: Yu Wang <wangy_km@yahoo.com>
To: si-list@silab.eng.sun.com <si-list@silab.eng.sun.com>
Date: Wednesday, March 22, 2000 1:52 AM
Subject: [SI-LIST] : how to combine multi components together with Orcad
layout

>Hi, all experts there,
>I am using Orcad(Ver.9.0) Layout plus to implement my
>design in which more than 30 pieces SMT FIFOs(TQFP128)
>and more than 70 pieces SMT 16 bit buffers and
>latchs(TVSOP48) are used. So I have to lay more than
>250 decoupling capacitors down and connect them to the
>PWR and GND pins. It's a tough work. However, because
>the layout and the connections of the capacitors for
>each FIFO or for each TVSOP48 chip are same. Then I
>think I can combine one FIFO and its capacitors
>together and regard them as one unit. It will simplify
>the job definitely. But I haven't found the tool
>within Orcad to realize it. What I am doing is
>creating a new layout pattern in which I use obstacle
>to draw some of the footprints of the chip and all the
>footprints of the capacitors and all the connections
>just like the old Orcad layout library did. Right now,
>for prototype,
>it can work good because I can solder the capacitors
>by hand. But, what I am worrying about is that in the
>future when I send it to production, the capacitors
>would not be assembled by machine. That will be a
>nightmare.
>So please, give any suggestions. Thanks a lot.
>
>
>
>=====
>Yu Wang, Ph.D
>U.T. MD Anderson Cancer Center
>1100 Holcombe Blvd., Box 217
>Houston, TX, 77030
>Tel:713-745-1671
>
>__________________________________________________
>Do You Yahoo!?
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>http://im.yahoo.com
>
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