---
title: "W5500 Crystal selection"
url: "https://maker.wiznet.io/forum/13859"
markdown_url: "https://maker.wiznet.io/forum/13859/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "Eagle5"
created: "2020-05-30T02:22:07+09:00"
last_activity: "2020-06-03T00:57:49+09:00"
language: "en"
views: 817
replies: 1
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# W5500 Crystal selection

## Question

Asked by Eagle5 on 2020-05-30 in Ethernet Chips.

Hi,

I have read numerous forums and conversations about the correct crystal selection for W5500 and I see lots of people had stability issues which makes me worried. Obviously the datasheet has mentioned some specific characteristics for the crystal: 25MHz, 30ppm Frequency tolerance, 18pF load capacitance. I have four questions:

1- What’s the ESR value I should aim for this crystal?

2- Is HC-49/US package preferred or 4-SMD?

3- Does this look like a good option: (FY2500016)

![](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/6/6f2a78d0f00e72e8a71fcd62b1b0452d878d8df6.png) [Mouser Electronics](https://www.mouser.com/ProductDetail/Diodes-Incorporated/FY2500016?qs=ZrPdAQfJ6DPs%252BuUDAtNVtA%3D%3D)

![](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/2/287cf2703dab83af8001da652b29130f53b22682.jpeg)

### [FY2500016 Diodes Incorporated | Mouser](https://www.mouser.com/ProductDetail/Diodes-Incorporated/FY2500016?qs=ZrPdAQfJ6DPs%252BuUDAtNVtA%3D%3D)

FY2500016 Diodes Incorporated Crystals 25.000MHz 18pF 30ppm -20 to +70 datasheet, inventory, & pricing.

If not what part number have you actually used in production and it worked perfectly?

4- For the load capacitance, is it a good practice to follow design reference from Wiznet which suggests 18pF capacitors. I understand following formula and assuming 5pF Cstray on the paper gives us 26pF not Wiznet’s suggestion of18pF.

Thank you,

## Replies

### Reply 1 by Eagle5, 2020-06-03

Any insight would be appreciated. Please advise.

---

Source: https://maker.wiznet.io/forum/13859