W5500 RSVD pins - connect to GND or leave floating?

Question

Hi. I saw that there is difference between application note and datasheet of W5500. What should I do with RSVD pins? There is schematic where each RSVD pin is floating (application note) docs.wiznet.io w5500_sch_v110_use_mag_.pdf 44.02 KB In datasheet there is information that 23 RSVD Pull-down I It must be tied to GND and Rest sould be floating. There is W5500 devboard where each RSVD is connected to GND via 10k resistor. docs.wiznet.io w5500_evb_v1.0_140527.pdf 63.69 KB What should I do?

Eugeny · Answer

These pins are already having internal pull-downs averaging at 85k. Thus the question is are these internal pull-downs enough and why some circuits have external pull-downs, and some not?

Eugeny · Answer

No idea. We must wait for WIZnet R&D to advise. If you need to make a design right now, just leave seats for those resistors, and will decide if to populate them or not later.

kewgal · Answer

Eugeny: u need to make a design right now, just leave seats for those resistors, and will decide if to po Thanks Eugeny. So we will wait

jaden · Answer

Hi kewgal As Eugeny said, W5500 RSVD pin has internal pull-down(thanks Eugeny!). The internal pull-down resistance value of 85K is too large and can be swayed by external noise. That’s why we used an external pull-down resistance of about 10K. Reset pin is internal pull-up but as the same reason with RVSD pin, it can be use with external pull-up. Thanks!