---
title: "w5300 impedance matching"
url: "https://maker.wiznet.io/forum/13081"
markdown_url: "https://maker.wiznet.io/forum/13081/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "Amin Naderi"
created: "2018-10-15T10:44:16+09:00"
last_activity: "2018-10-15T14:14:10+09:00"
language: "en"
views: 993
replies: 1
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# w5300 impedance matching

## Question

Asked by Amin Naderi on 2018-10-15 in Ethernet Chips.

hi all.
I’m designing a pcb board with spartan-6 and w5300 TCP/IP module.
in datasheet of w5300 say’s for better impedance matching you have to place 50ohm res and 0.1uf cap like the picture

[![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/5/5432d41dadf5842a5ae5502ac84830da5a893a5a.png) image755×402 19.2 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/5/5432d41dadf5842a5ae5502ac84830da5a893a5a.png)

. I’m using HR911105A rj-45 connector with magnetic module.
this connector uses 75ohm resistor and 1000pf cap
[datasheet of HR91115A](http://www.kosmodrom.com.ua/pdf/HR911105A.pdf)
my question is despite the 75 ohm resistor’s and 1000pf capacitors in this connector do i still need to place 50 ohm and 100nf cap?

## Replies

### Reply 1 by Eugeny, 2018-10-15

![](https://avatars.discourse-cdn.com/v4/letter/a/7ba0ec/48.png) Amin_Naderi:

> in datasheet of w5300 say’s for better impedance matching you have to place 50ohm res

50 Ohm? There’re no such resistors in the circuit.

![](https://avatars.discourse-cdn.com/v4/letter/a/7ba0ec/48.png) Amin_Naderi:

> my question is despite the 75 ohm resistor’s and 1000pf capacitors in this connector do i still need to place

Yes, you still need to place these components because they are located in different part of the circuit.

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Source: https://maker.wiznet.io/forum/13081