[SI-LIST] Re: add new power island in a 8 layer stack
- From: "Tom Biggs" <tbiggs@xxxxxxxxxxxxxxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Fri, 9 Jul 2004 13:57:03 -0700
When you create a power island on a signal layer and you have two signal
layers between planes, then you might want to create an equivalent
ground island on the next layer (properly stitched to the ground plane).
This prevents auto-routed traces from crossing under this power island,
which would cause EMI and signal quality problems.
-tom
-----Original Message-----
From: steve weir [mailto:weirsp@xxxxxxxxxx]=20
Sent: Friday, July 09, 2004 1:46 PM
To: calaf_calaf_calaf@xxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: add new power island in a 8 layer stack
Calaf, when islanding power, power routing moves to signal layers and
only=20
the correct potential, usually ground is used for signal return planes.
To=20
avoid EMI problems, signals need contiguous returns. Digital ground is=20
digital ground. If you don't stitch your 2.5V and 1.2V returns together
you will have massive EMC and ground bounce problems.
Steve.
At 09:50 AM 7/9/2004 +0000, calaf_calaf_calaf wrote:
>Hi again,
>I do not get how adding and 2.5V power island in a signal plane. The=20
>fact is that I need four layers for power and gnd, and four layers for=20
>signal routing. Can I use any of the signal layers for such island?=20
>should I add a gnd island for that 2.5V island? Can I share gnd layer=20
>between 2.5V island and 1.2V layer? Can I separate one power plane in=20
>two layer or I should leave 3.3V plane in one layer and 1.2V plane in=20
>just another? Thank you for any help you can tell me
>Regards
>
>------------------------------------------------------------------
>To unsubscribe from si-list:
>si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>
>or to administer your membership from a web page, go to:=20
>//www.freelists.org/webpage/si-list
>
>For help:
>si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>
>List FAQ wiki page is located at:
> http://si-list.org/wiki/wiki.pl?Si-List_FAQ
>
>List technical documents are available at:
> http://www.si-list.org
>
>List archives are viewable at:
> //www.freelists.org/archives/si-list
>or at our remote archives:
> http://groups.yahoo.com/group/si-list/messages
>Old (prior to June 6, 2001) list archives are viewable at:
> http://www.qsl.net/wb6tpu
>
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
List archives are viewable at: =20
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
=20
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
