---
title: "Problem with Xtal Pins"
url: "https://maker.wiznet.io/forum/10193"
markdown_url: "https://maker.wiznet.io/forum/10193/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "EEProjs"
created: "2014-04-30T12:31:53+09:00"
last_activity: "2017-05-04T08:32:40+09:00"
language: "en"
views: 546
replies: 2
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# Problem with Xtal Pins

## Question

Asked by EEProjs on 2014-04-30 in Ethernet Chips.

Hi, I’ve designed a board with TWO W5300 on it,
I used a 25MHz crystal oscillator for each.(
CRYSTAL 25.0MHZ 18PF 20ppm 100 ohm, SMD , MANF PN:ABLS-25.000MHZ-B2F-T)

when I started the hardware test I had no Clock on Xtal Pins, I tried changing Xtal Capacitors by values of 13PF,18PF, 22PF, 33PF, 46PF and 56PF
Now one of them oscillates with 46PF capacitor installed but the other has no oscillation.
I tried changing that Xtal with NTK 25MHz Xtal but also have Problem with it,
Please help me to rectify this problem.

## Replies

### Reply 1 by peter, 2014-05-02

It seems like load-capacitance matching problem.
Load capacitance matching is affected by versatile factors. (pcb routing status, copper thickness(oz)……)
If 18Pf of CL value, theoretically, I recommend 39pF external capacitors. Or, 1.8V level oscillator can be used.

### Reply 2 by EEProjs, 2014-05-03

Thanks for reply,

PCB is designed on 50 Ohm tracks like below:
Track width= 4.5 mil,
copper thickness: 3 mil
dielectric constant: 4.3

is 50 ohm impedance matching OK for Xtal Pins?

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Source: https://maker.wiznet.io/forum/10193