Capacitive Coupling With W5200

Question

Hello, I am preparing to implement a link between a W5200 PICTail board and a KSZ8999 ethernet switch. I’ve removed the MagJack and relevant pull-up resistors, and forced the W5200 into 10Base-T operation. I already have a verified capacitive coupling circuit per Micrel AN-120 ([url]http://www.micrel.com/_PDF/Ethernet/app-notes/an-120.pdf[/url]) to go between the KSZ8999 and some device which has a receiver with internal DC biasing (formerly an ENC28J60). Software has already been developed for the PIC controlling the W5200 using a stock PICTail board connected to a host PC via CAT5. My question is, does the W5200 also have internal DC biasing? If so, I should be able to just disconnect my ENC28J60 and replace it with my modified W5200. If not, this means I need to change my capacitive coupling circuit slightly. The RX pair needs to be pulled up directly to 3.3V without internal DC biasing, and through a 0.1u capacitor if internal DC biasing is there. Also, does anyone have a pinout of the MagJack on the PICTail board (BS-RB10005)? I can’t find a datasheet for it. I think I’ve figured it out based on the placement of resistors, but I’d like to be sure.

hjjeon0608 · Answer

Hi, fbivona. There is not officially recommended method to connect PHY to PHY. And also We didn’t test and verify about internal DC biasing. So, I don’t guarantee about that and make a decision by designer. Best regards.