Weird symbol/footprint. What do you think?

Once in a while, I am < 100% certain of the connection of two inputs to two outputs. Is it input A to output 1 and input B to output 2, or is it input B to output 1 and input A to output 1? In this particular case I have never before used a shaft encoder. I want to use one to control a digipot and get the rotation direction correct. I want the flexibility to correct the connection when I test the board.

This can be done with four resistors (or jumpers) but that would take 8 pads and I wanted to try saving board space. So I devised this symbol and footprint to fit two 0603 resistors. The idea is to place the two chips vertically for one option or horizontally for the other. This becomes one footprint and symbol which fits two real components. So it would raise havoc in a BOM. It has that issue for commercial production. But building a board myself, I do not need to argue with a buyer or production engineer.

I guess I could alternatively place four chip resistors with overlapping pads, and then argue with DRC. :slight_smile: Maybe that is no worse. Is this nuts?

I would go the route with separate footprints and overlapping pads. Reason is that you can actually see in the 3D viewer if the resistors themselves fit and how much you can overlap the pads.

Also consider those 0603 resistors are rectangular. Putting them in a square leaves an open space in the middle. It would be more logical if you put all resistors in the same orientation.

Once you’ve found an orientation of your resistors that you are happy with, you could replace it with something like in your above screenshots, but then you at least know how big you want your pads to be and at which locations.

Thanks for the feedback.

I have never used the 3d viewer and have no plans or interest in it right now.

Yes but don’t you normally need a space (at least a courtyard) between components?

Years ago when I was working on some of my first SMT designs I worked with a designer who I think was using PADS. His 0603 footprints could actually fit 0805 chips (but without a lot of extra room). My normal MO is to use something similar to the standard 0805 footprint (I call it a small 0805) for 0603s. I also have a fat 0805 footprint for when I really want to use an 0805 chip but (except for values <0.1 ohms) I jump to 1206 and do not stock or normally use 0805 resistors. The pads in my cross connect footprint are square and dimensionally close to the small 0805. (Actually my small 0805 has pads which are 40 mils long x 50 mils wide. This new one is 45 square.) I don’t think there is (significantly more than normal) space between the two 0603s. FYI related to the screenshot below:

  1. Pad 1 is at 0,0
  2. The pads and their arrangement are square; X dimensions = Y dimensions.

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.