---
title: "No link with PoE+ jack (integrated magnetics)"
url: "https://maker.wiznet.io/forum/15957"
markdown_url: "https://maker.wiznet.io/forum/15957/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "cholin"
created: "2025-12-19T03:48:42+09:00"
last_activity: "2025-12-20T03:18:43+09:00"
language: "en"
tags: ["W5500", "PoE"]
views: 6
replies: 2
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# No link with PoE+ jack (integrated magnetics)

## Question

Asked by cholin on 2025-12-19 in Ethernet Chips.

I designed a circuit using W5500 and a PoE+ enabled jack with integrated magnetics. I am unable to establish a link and I suspect that the magnetics and bias circuit are not compatible. Do you have any reference designs for PoE+ magnetics with W5500?

I have seen this project but the schematic is too small to read: <https://maker.wiznet.io/Alan/projects/raspberry%2Dpi%2D5%2Dpoe%2Dhat/>

I have attached my schematic and the magnetics of the PoE+ jack - note that all PoE+ jacks use the same magnetics, where the common mode choke is AFTER the transformer. Here is a link to the images <https://imgur.com/a/LDkLVlW>

I can communicate over SPI and I confirmed the oscillator is running at 25MHz. I have tried bridging TCT and RCT with no luck. I have also tried removing the capacitors C29 and C30. I have tried auto-negotation and forcing 10BASE-T, neither works.

I am able to get power from the switch when I use a PoE switch. I have also tried with a non-PoE switch and I get no link.

Can you give ideas or reference designs for PoE+ jacks?

Thank you!

## Replies

### Reply 1 by Alan, 2025-12-19

Sorry. We do not provide a reference for PoE+.
You may purchase and use a PoE+ module separately.
However, please understand that we cannot provide support for developing your own PoE+ module.

### Reply 2 by cholin, 2025-12-20

Nevermind, I was able to diagnose the issue - the magnetics work perfectly with no other changes required.

---

Source: https://maker.wiznet.io/forum/15957