---
title: "Connecting W5500 to a Molex Magjack"
url: "https://maker.wiznet.io/forum/12747"
markdown_url: "https://maker.wiznet.io/forum/12747/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "t.lederer"
created: "2018-02-13T10:50:16+09:00"
last_activity: "2018-02-13T11:49:53+09:00"
language: "en"
views: 895
replies: 2
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# Connecting W5500 to a Molex Magjack

## Question

Asked by t.lederer on 2018-02-13 in Ethernet Chips.

Hello,

i want to use the W5500 in a Master Controller.
Currently i copied the Reference Schematic of the “W5500 Ethernet Shield” as i don´t have a single clue on how to design the schematic around Magjacks (J1B1211CCD currently used as in reference).

Now here is the Problem: My Board will sit very flat on a surface and the Tab Down Connectors are not an option,
So i searched for Tab-Up Magjacks and Arrived at this Molex Part: [Molex Datasheet](https://www.molex.com/pdm_docs/sd/937555226_sd.pdf).

This Connector from Molex does not have the Center Taps (ct) routed out, but connected internally to chassis ground with a bunch of 75 Ohm Resistors.

Question is now: What is the best way of connecting this Jack to the W5500 (looking for the schematic).
or: Is there a Recommended Connector that has the Tab facing up and is Placed ontop of the Board (Nod Mid-placed like the one on the W5500 Ethernet Shield).

I would really appreciate your help.

Best Regards,
Tibor

## Replies

### Reply 1 by Eugeny, 2018-02-13

![](https://avatars.discourse-cdn.com/v4/letter/t/5daacb/48.png) t.lederer:

> So i searched for Tab-Up Magjacks

Orientation of the tab should not matter if specifications match.

![](https://avatars.discourse-cdn.com/v4/letter/t/5daacb/48.png) t.lederer:

> This Connector from Molex does not have the Center Taps (ct) routed out, but connected internally to chassis ground with a bunch of 75 Ohm Resistors.

You look at its circuit diagram from wrong end. PHY side is to the right, not to the left. In general part looks appropriate having symmetrical transformer design. But to be 100% sure you would better do prototyping anyway.

![](https://avatars.discourse-cdn.com/v4/letter/t/5daacb/48.png) t.lederer:

> What is the best way of connecting this Jack to the W5500 (looking for the schematic).

The exactly the same way as reference schematic says, you should have no problem with it, just do not confuse MagJack’s pins.

### Reply 2 by t.lederer, 2018-02-13 (in reply to reply 1)

Oh my, i really did not realize the sides were different.
Many thanks for your Quick and Useful answer.

Just for clarification: The Tab-Orientation is only important because of mechanical restrictions.

---

Source: https://maker.wiznet.io/forum/12747