layout question regarding the reference schematic

Question

Hello - I have a layout question regarding the reference schematic for W5500 http://wizwiki.net/wiki/lib/exe/fetch.php?media=wiznet_schematic:ethernet_chip:w5500_sch_v110_use_mag_.pdf Its a shame no PCB layout is provided… Should I locate R1 R2 R3 / R6 R7 - near(er) the W5500 chip or the RJ45 socket? Which side do they ‘terminate’? Where is it best to put C9 C10 - near(er) the W5500 chip or the RJ45 socket? I’ll locate R21 to R24 near the W5500 - i think that’s obvious. Thanks…

Eugeny · Answer

You can look in here into layout guide for W5100. Principles for W5500 are the same. In my experience, most critical are: crystal placing; GND planes; trace routing (shape, closeness of + and -, their length) Regarding block A and B: I examined several PCBs with other chips (Intel) and they have relatively long traces between chip and magnetics, A and B located somewhere in the center of pathway. Thus your task would be just keep + and - traces as short as possible, as close to each other as possible, as mirrored as possible, and place these resistors/caps in the most convenient place.

Eugeny · Answer

jnewcomb: I’ll stick with the W5500 schematic. You MUST stick to schematic of the chip you use, in this case W5500. That document contains design guidelines in general, which are good to implement to minimize design issues.