W5500 Design Tipps / review

Question

I’m designing my first ethernet board and I’m not so experienced with hf applications. I would like to show you my schematic and Layout, which is inspired by the Wiznet Ethernet shield. 3V3 and Gnd are not routed yet, but on the bottom layer there is plenty of space. questions: a) is my schematic ok? b) what do you think about my layout / routing c) where to place GND and where to place GNDA planes? w5500_schematic1224×830 20.6 KB w5500_layout1641×740 81.1 KB

Eugeny · Answer

You do not use reset pin? Some components do not have part numbers. Power conductors of the same width as signal? There’s a document with guidelines, must be in the HW design guide archive on the W5100 product web page.

Ing-Dom · Answer

Thanks for your reply. I thought, as I can shut down the power from my Controllerboard (with a RP2040, btw) I don’t need the reset… what do you think? I have only 3 GPIOs left… What do you mean with “Power conductors of the same width as signal?” what part numbers are missing?

Ing-Dom · Answer

All right, I read the design doc ! Did some adaptions in the schematic (got rid of analog ground), connected RES and INT, added part numbers for special components. w5500_schematic1152×779 16.4 KB 3.3v traces are to thin you say… I barely routed power traces, just some very short for the decoupling C - I wanted to route power mostly on bottom after I have my hf stuff. to which traces do you refer exactly? C12 crossing is awfull you said - yes! But I’m stuck here, because R13 and R14 both connect to P5 and to RXN and RXP lines. w5500_layout_alt11079×575 52.4 KB not made nice, but possible ?! w5500_layout_alt21216×491 42.7 KB Can I use vias at any place in this RX circuitry?

Ing-Dom · Answer

w5500_layout_alt31661×811 85.8 KB I searched through this Forum for some ideas and adapted one which you said “looks good” What do you think? Only think which I’m not satisfied with is the R13 connection to the MagJack. Should I make the “direct” RX/TXpairs 8 mil as stated in the design guide?

Ing-Dom · Answer

that was the idea, because the plan is to let JLCPCB assemble that board. It’s for an OpenSource project (OpenKNX), and we do not have a big budget. Which components would you place on bottom side? R12/C11 and R13/14 and C14 ?

Ing-Dom · Answer

w5500_layout_alt41491×726 73.1 KB what do you think about that one? It needs a little tweaking here and there but the general idea?