---
title: "Capacitive Coupling With W5200"
url: "https://maker.wiznet.io/forum/9606"
markdown_url: "https://maker.wiznet.io/forum/9606/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "fbivona"
created: "2013-10-02T14:12:45+09:00"
last_activity: "2017-05-04T08:30:09+09:00"
language: "en"
views: 640
replies: 1
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# Capacitive Coupling With W5200

## Question

Asked by fbivona on 2013-10-02 in Ethernet Chips.

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\[/url\]](http://www.micrel.com/_PDF/Ethernet/app-notes/an-120.pdf%5B/url%5D)) 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.

## Replies

### Reply 1 by hjjeon0608, 2013-10-04

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.

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Source: https://maker.wiznet.io/forum/9606