Re: gEDA-user: pcb, howto partition power planes?

[Steve Meier <smeier@xxxxxxxxxxxxxxxxxxx>]

Ok ok ok go to my home page and look for links to hs table of contents
and hs section 1 through 4


http://www.alchemyresearch.com/


Steve Meier


On Thu, 2008-10-30 at 16:29 -0400, Dave McGuire wrote:
> I don't see any URLs in there..
> 
>           -Dave
> 
> On Oct 29, 2008, at 6:08 PM, Steve Meier wrote:
> > I went looking to see if the Analog Device book was available
> > electronically. Here are the links.
> >
> >
> > Steve Meier
> >
> >
> > High Speed System Applications Table of Contents
> >
> >
> >
> > High Speed System Applications Section 1: High Speed Data Conversion
> > Overview
> >
> >
> >
> > High Speed System Applications Section 2: Optimizing Data Converter
> > Interfaces
> >
> >
> >
> > High Speed System Applications Section 3: DAC, DDS, PLL's, and Clock
> > Distribution
> >
> >
> >
> >
> > High Speed System Applications Section 4: PC Board Layout and Design
> > Tools
> >
> >
> >
> > On Tue, 2008-10-28 at 13:44 -0700, Steve Meier wrote:
> >> I won't argue this point. I will refer every one to an Analog Device
> >> publication "High Speed System Applications" copyright 2006 ISBN-10:
> >> 1-56619-909-3  or ISBN-13: 978-1-56619-909-4
> >>
> >> In particular if you get a copy of this book (and they gave me mine)
> >> look at pages 4.15 and 4.16
> >>
> >> There AD recommends connecting both of the A/D grounds "digital" and
> >> "analog" to the analog ground plane "this is because it causes less
> >> problems for the relatively small amount of digital return current  
> >> to be
> >> returned through the analog ground than it would to connect the
> >> converter to the much noisy digital ground.
> >>
> >> There is a lot more talked about then just that one blurb.
> >>
> >> Steve Meier
> >>
> >>
> >>
> >> On Tue, 2008-10-28 at 11:22 -0700, Joerg wrote:
> >>> Stefan Salewski wrote:
> >>>> Sometimes it is necessary/recommended to partition (separate)  
> >>>> power or
> >>>> ground planes, i.e. for ADC or DC/DC-Converters, see page 16 and  
> >>>> 17 in
> >>>>
> >>>> http://focus.ti.com/lit/ug/slwu028c/slwu028c.pdf
> >>>>
> >>>> We can do this in pcb program with (adjoining) polygons.
> >>>> Disadvantage is, that if we change the size of one of the  
> >>>> polygons we
> >>>> have to manually adjust the other sizes. A other method may be  
> >>>> so divide
> >>>> a large polygon by copper clearing traces (with trace width zero).
> >>>>
> >>>> This is related to my question from
> >>>>
> >>>> http://archives.seul.org/geda/user/Sep-2008/msg00387.html
> >>>>
> >>>> but not identical.
> >>>>
> >>>> What is the best way to handle this?
> >>>>
> >>>
> >>> I can't speak to that but just one word of caution: In my 20+  
> >>> years in
> >>> engineering I have yet to see one case where splitting a ground  
> >>> plane
> >>> under high-speed ADCs has worked. Regardless of what application  
> >>> notes
> >>> say. Usually it didn't work, lots of noise. Or it kind of worked but
> >>> fell apart the instant somebody whipped out a GSM cell phone or  
> >>> BlackBerry.
> >>>
> >>> Myself, I never spilt a ground place. OTOH the industry practice of
> >>> splitting planes is providing part of my income :-)
> >>>
> >>> The only time I split is where required for safety, for example  
> >>> patient
> >>> isolation per 60601 (ECG, ultrasound etc.).
> >>>
> >>
> >>
> >>
> >> _______________________________________________
> >> geda-user mailing list
> >> geda-user@xxxxxxxxxxxxxx
> >> http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
> >
> >
> >
> > _______________________________________________
> > geda-user mailing list
> > geda-user@xxxxxxxxxxxxxx
> > http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
> 
> 



_______________________________________________
geda-user mailing list
geda-user@xxxxxxxxxxxxxx
http://www.seul.org/cgi-bin/mailman/listinfo/geda-user