---
title: "‘Symmetrical or Asymmetrical' Transformer"
url: "https://maker.wiznet.io/forum/12294"
markdown_url: "https://maker.wiznet.io/forum/12294/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "jnewcomb"
created: "2017-05-19T11:02:55+09:00"
last_activity: "2017-05-19T11:51:41+09:00"
language: "en"
views: 1027
replies: 3
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# ‘Symmetrical or Asymmetrical' Transformer

## Question

Asked by jnewcomb on 2017-05-19 in Ethernet Chips.

Reading this forum, the advice is the magnetics need to be in a ‘Symmetrical Transformer’ arrangement.

But… I have initially based my design using this connector:

![](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/8/879356dce64ad611e29aa103ff788898487d166b.png) [MIKROE](https://www.mikroe.com/eth-wiz-click)

![](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/b/b2b1b60bfc4861133a793ab23d30488e34857ea0.jpeg)

### [ETH Wiz click | Mikroe](https://www.mikroe.com/eth-wiz-click)

ETH Wiz click™ carries W5500, a 48-pin, 10/100 BASE-TX standalone Ethernet controller with a hardwired TCP/IP Internet protocol offload engine, MIKROE-1718

Price: $19.00

Which uses the LPJ0026GENL

![](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/1/19af5adcd1a1c90a947c3a70ac400f009a42de4b.png) [link-pp.com](http://www.link-pp.com/?product%2F201604202787.html)

### [LPJ0026GENL , MIC25013-5110T-LF3 / MIC25013-511T-LF3​ , RJ45 Connector , RJ45...](http://www.link-pp.com/?product%2F201604202787.html)

With low price but high-quality UL Certification LPJ0026GENL , MIC25013-5110T-LF3 / MIC25013-511T-LF3​ , RJ45 Connector , RJ45 Jack , RJ45 Female Connector , RJ45 Modular Jack , Ethernet RJ45 Connector , 8P8C RJ45 Connector , SMT RJ45 Connector ,...

The datasheet clearly shows it’s an Asymmetrical transformer.
… So I just want to check if I should change my design (it’s still possible)
Have they selected the wrong magnetics??

## Replies

### Reply 1 by Eugeny, 2017-05-19

jnewcomb:

> So I just want to check if I should change my design (it’s still possible)
> Have they selected the wrong magnetics??

Symmetrical transformer is important in applications which support auto-[MDI-X](https://en.wikipedia.org/wiki/Medium-dependent_interface).

W5500’s datasheet states:

> 5.5.6 MDIX
> W5500 does not support auto-MDIX feature.

Thus I do not think there’s a reason to change transformer type **if PHY is properly operational with your chosen one**.

### Reply 2 by jnewcomb, 2017-05-19 (in reply to reply 1)

The device is going to be plugged into a switch (which supports auto-MDIX)
They will probably use a patch cable, but I don’t want a support request if they use a crossover.
Based on your advice - I suppose I better stick with the reference design as suggested by Wiznet…
Thanks.

### Reply 3 by Eugeny, 2017-05-19

jnewcomb:

> I better stick with the reference design as suggested by Wiznet

I am sure it is wise decision ![:slight_smile:](https://emoji.discourse-cdn.com/twitter/slight_smile.png?v=12)

---

Source: https://maker.wiznet.io/forum/12294