Capacitive Coupling With W5200



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 ( 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.


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.