Re: Tips on routing this high density/high current board? I'm stuck - any ideas?

On Thu, 23 Nov 2006 11:59:25 -0000, "CWatters" <colin.watters@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:


<ferrari.secret.santa@xxxxxxxxx> wrote in message
news:1163737880.617363.267490@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I am building a display consisting of a series of seven 5x7 LED dot
matrix displays, butted up against one another. The displays are of
the 0.7" variety (about as small as they come). I will be driving them
with PWM to control brightness, using shift registers to control the 35
horizontal elements, and switching the 7 rows sequentially to paint the
display. The pulse current on each dot is 100ma, and times 35
horizontal dots, that's a potential max of 3.5A.

Problem is, I am trying to keep the board small. The traces required
to handle 3.5A are pretty fat - too fat to allow the close spacing I
need for the project.

Perhaps use bus bars. Strips of plated copper with legs. They stand
vertically and can be bent to go around corners.


Or more layers, or specify heavier (thicker) copper -35u is standard, but you can get 70u and 105u
Also, consider to what extent the voltage drop actually matters - the power is going to turn into
heat somewhere - displays, resistors, drivers, and you may be able to live with a bit burning off in
the PCB tracks.
.