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

[Steve Meier <smeier@xxxxxxxxxxxxxxxxxxx>]

On the issue of powering boards I have been playing with some really
neat programmable power supply controllers (surface mount chip) that
support power supply modules. Prices of the modules seem to be
comparable to the prices of the individual components one would need to
build various forms of switching power supplies. The controllers set the
duty cycle, phase and frequency of the switching power supplies. This
makes it possible to insure that two switchers are switching out of
phase with each other. Other parameters which are controlled are delays
from power up and rate of power up.

So one other trick I use is to isolate each power supply from the rest
of the board with a jumper (large diameter holes to support a fat wire).
Then when we first turn on the board, we program the power supplies
check out their voltages, ringing etc and then we connect them via the
jumper to the rest of the board.

Steve Meier


On Mon, 2008-10-27 at 14:43 -0700, Steve Meier wrote:
> I agree with Niel, I separate my ground planes with a symbol for a power
> inductor. I do this at the schematic level and then I read the layout
> suggestions typically provided by the A/D data sheet on where to connect
> the planes. For the fab I put in the power inductor foot print. You can
> then use the power inductor or not. You can leave it open or you can
> short it.
> 
> I also do similar activities for power supplies separating the board
> power from board sections. Makes it very easy to debug the board from
> one section to the next.
> 
> Steve Meier
> 
> 
> On Mon, 2008-10-27 at 19:47 +0200, Duncan Drennan wrote:
> > >> I typically deal with this by separating the planes at the schematic
> > >> level using a bead-core inductor.
> > 
> > > Yes, I also have GND and AGND in my schematics.
> > 
> > Don't put inductors between ground planes, connect them at a star
> > point. If you are going to use inductors then have them on the power
> > side, not between grounds.
> > 
> > > How do I best divide a copper area (physically) into subsections with
> > > complicated shape/outline.
> > 
> > Is there a good way to do this with PCB? It would be relatively easy
> > if planes could be handled as negatives, i.e. everything you see is
> > NOT there. Then it is just a matter of moving a line.
> > 
> > 
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> 
> 
> 
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