---
title: "Running chips without MagJack attached"
url: "https://maker.wiznet.io/forum/11386"
markdown_url: "https://maker.wiznet.io/forum/11386/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "Eugeny"
created: "2015-10-16T16:58:40+09:00"
last_activity: "2017-05-04T08:37:54+09:00"
language: "en"
views: 433
replies: 6
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# Running chips without MagJack attached

## Question

Asked by Eugeny on 2015-10-16 in Ethernet Chips.

Hello, will WIZnet TCP/IP device damage or degrade if it will be running without MagJack attached (without a load on its PHY output) for a while?
To be precise I use W5100. I am having other components on the board to troubleshoot, but did not solder MagJack because it did not arrive yet.
Please advise.
Thank you.
Eugeny

## Replies

### Reply 1 by Edward, 2015-10-19

Hi.

TCP/IP device is Not damage without PHY and Magjack.

But, caution !

What kind using the chip?

refer to bellow W5500 reference circuit and check to [Wizwiki.net](http://Wizwiki.net) (forum site)

[wizwiki.net/wiki/doku.php?id=pro … fschematic](http://wizwiki.net/wiki/doku.php?id=products:w5500:refschematic)

Thank you

### Reply 2 by Eugeny, 2015-10-19

Thank you.

Edward:

> What kind using the chip?

W5100

Edward:

> TCP/IP device is Not damage without PHY and Magjack. But, caution !

Which caution?

### Reply 3 by Edward, 2015-10-19

Caution is schematic design.

You design correct circuit, otherwise dangerous.

So, refer to below site

[wiznet.co.kr/product-item/w5100/](http://www.wiznet.co.kr/product-item/w5100/)

check the HW Design Guide Tap.

It is W5100 Reference circuit.

Thank you

### Reply 4 by Eugeny, 2015-10-20

Edward, you seem to answer different question.

Assume that schematic is fully correct, but I do not solder MagJack connector. Is there any danger?

### Reply 5 by Edward, 2015-11-05

It is not danger.

Just RJ-45 and Transformer use reason is communication to other peer.

you just checking phy signal? It is not danger

thank you

### Reply 6 by Eugeny, 2016-01-04

Thank you.

---

Source: https://maker.wiznet.io/forum/11386