DP83869HM: Intermittent link going down and coming up again

Hi Genpesh,

Thank you for sharing the information. I would like ask information for further debug.

• May I ask what is the cable length that you are using ?
• If possible, could you share the schematic around the MDI and magnetic side?

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Thank you,

Hillman Lin

Hi Hillman,

Please find answers for your questions,

1.May I ask what is the cable length that you are using ?

Ans: 2.5 Meters (Cat 5e)

2.If possible, could you share the schematic around the MDI and magnetic side?

Thanks,

Hi Ganesh,

If possible, could you also provide the connection between magnetic and RJ45 connector?

We also have layout recommendation, could you also take a look on the layout recommendation?

• MDI trace length, MDI impedance matching, and MDI gap between each pair of cable
• 6646.Industrial_PHY_Layout Review Checklist.xlsx

We also have DP83869 troubleshooting guide that you could refer to:

• https://www.ti.com/lit/an/snla443/snla443.pdf?ts=1733518797113&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FDP83869HM

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Regards,

Hillman Lin

Hi hillman lin

We have use circuiar connectors used for Etherenet and from there ethernet cables are used for Testing.

We have gone through the PCB Guidelines and Troubleshoot guidelines. Everything looks okay to me.

We are observing sometimes it is automatically link up 100Mbps and sometimes it is taking too long to link up with 1G and when link is up, while pinging sometimes link goes and comes

Hi Ganesh,

In most scenario, PHY is moving from 1Gbps to 100Mbps are due to the bad signal quality. That is why we are asking for schematic and layout.

Non-RJ45 connector are normally not recommended due to the impedance mismatch.

If possible, could you run a quick compliance test on the MDI lines to check on the signal quality?

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Thank you,

Hillman Lin