I'm creating a DC-DC switching buck regulator using the LM2596 5A regulator from texas instruments to convert 12V@3A to 5V upto 5A.

Since this is a high current circuit to feed servos, I've tried to keep the traces as thick as possible but since the size of the board is small and restricted by the mechanical dimensions of the enclosure, I've been concerned about trace width. I recently came across another approach of using polygons in Eagle to create thicker planes.

Which of the 2 layouts would be better:

Layout 1: Using regular traces. Most of the high current traces are atleast 100mil thick which according to a trace width calculator should be good for 5A.

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Layout 2: Using larger polygons for planes. This also allows me to end neatly in pads that are much smaller than the trace and have small SMD decoupling caps connect to easily.

enter image description here

Which of these approaches is better and why? Or am I simply over engineering at this stage?

I'm using a 2 layer 1oz circuit board. 2oz board currently is not possible to use. Also I'm yet to add stitching vias.

  • 1
    \$\begingroup\$ +12 V on the bottom capacitor on #1 has an etch pocket. Avoid that. \$\endgroup\$
    – winny
    Sep 15, 2018 at 19:42
  • 1
    \$\begingroup\$ your heatsink vias under the chip are probably all the stitching needed. pin3 should probably connect to the main pad instead of an extra via. \$\endgroup\$
    – Jasen
    Sep 15, 2018 at 19:45
  • \$\begingroup\$ I didn't do any math, but at a glance the heat sinking looks waaaays to small \$\endgroup\$
    – carloc
    Sep 15, 2018 at 20:00

1 Answer 1


I see no reason why you could not draw one like the second using wide traces instead of polygons, the only hard bit is you need to miss some of the pads with the end of the trace.

Such short traces can handle more than 5A, this is good because the RMS current in them, will be more than 5A.

Perhaps add extra solder to the trace from pin 2 to the via.


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