---
title: "High operating temperature test"
url: "https://maker.wiznet.io/forum/13769"
markdown_url: "https://maker.wiznet.io/forum/13769/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "mokona79"
created: "2020-04-01T12:48:31+09:00"
last_activity: "2020-04-01T12:48:31+09:00"
language: "en"
views: 403
replies: 0
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# High operating temperature test

## Question

Asked by mokona79 on 2020-04-01 in Ethernet Chips.

Hi,
I am interested in the W5100s to apply in the military program.
The HW design needs to consider 71 Celsius ambient (air) temperature.
But depending on power dissipation of this chip, ambient temperature could rise and 105 C operating temperature was a guideline when selecting chips in previous programs.

Operating temperature of W5100s is -40 C to 85 C.
However, I have found the HTOL report of the W5100 that had passed 125 C for 502 hours.
I think these chip are same family, so the W5100s might operate at 105 C.
Do you have the HTOL report of the W5100s or similar temperature test report?

Thank you, in advance.
Sungyoon

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Source: https://maker.wiznet.io/forum/13769