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

[Steve Meier <smeier@xxxxxxxxxxxxxxxxxxx>]

Dave,

No I struggled three times to get usable url's so go down a couple more
of my attempts and then you will have to take the line breaks out of the
ultra long url but you can get there.

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