---
title: "W6100-io module RX TX ESD protection"
url: "https://maker.wiznet.io/forum/16181"
markdown_url: "https://maker.wiznet.io/forum/16181/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "chrisyue"
created: "2026-10-20T17:11:24+09:00"
last_activity: "2026-10-22T17:32:34+09:00"
language: "en"
views: 4
replies: 3
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# W6100-io module RX TX ESD protection

## Question

Asked by chrisyue on 2026-10-20 in Ethernet Chips.

Hello, we are developing a 100Mbps PoE test board using a W6100-io module and discrete Ethernet magnetics. We have experienced damage to the W6100 RX inputs during Ethernet cable insertion/removal and would like guidance on ESD protection for the PHY-side TX+/TX− and RX+/RX− signals. With the external ESD devices removed, measurements during normal Ethernet operation showed single-ended voltages relative to PHY ground of approximately 2.52–4.04V on RX and 2.12–4.40V on TX, with an average bias of about 3.3V. These measurements used ×10 passive probes with long ground leads, so measurement-induced effects on the peaks have not been ruled out. Could you confirm the permitted normal single-ended voltage range and the allowable transient overvoltage/undershoot amplitudes and durations for these four analog pins? Please also recommend the external ESD device working voltage, clamping specifications, maximum capacitance, and connection topology. In particular, is a nominal 3.3V device such as RClamp3304N suitable for this bias and signal swing, or should a different voltage rating or protection topology be used? Recommended part numbers and a W6100-specific reference schematic would be appreciated. Thank you.

## Replies

### Reply 1 by Alan, 2026-10-21

Hello, and I apologize for the delayed response.

First, could you please provide the circuit schematic?

We have not encountered any ESD-related issues with the W6100.
I believe there may be some underlying issue in the design that is causing this problem.

### Reply 2 by chrisyue, 2026-10-22

![](https://maker.wiznet.io/upload/ckeditor5/0135e7a5e510485393e181556a43cc9a.png)

Can ESD of Vrwm (5V or 5.5V) protect IC?

### Reply 3 by chrisyue, 2026-10-22

![](https://maker.wiznet.io/upload/ckeditor5/3aabd98538664f5484c077bbbe9e2cdc.png)

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Source: https://maker.wiznet.io/forum/16181