DP83867CR: some switches can't link and the RX_CLK is unstable

Kailyn Chen

Part Number: DP83867CR

Hello，

One customer used DP83867C for his application and found that some switches don't link, he tested the RX_CLK curve, and the RX_CLK of the switch which doesn't link is unstable. Please refer to the below curve and video.

Best regards

kailyn

over 2 years ago

0 Gokul Koraganji over 2 years ago

TI__Mastermind 19250 points

Hi Kailyn,

The behavior is expected for unstable links. In the image you can see that RX_CLK is switching from 2.5MHz to 25MHz. It means that the link is temporarily changing to 100Mbps link and falling back to auto-negotiation (during auto-negotiation, RX_CLK frequency will be 2.5MHz).

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Regards,
Gokul.

0 Kailyn Chen over 2 years ago in reply to Gokul Koraganji

TI__Genius 9560 points

Hi Gokul,

Thank you for your reply, but how to resolve it ?

The customer gave feedback that there is one switch H3C_S1008V could work normally, other two switches aren't stable. Attached is the schematic, please help to analyze.

5008.DP83867-3.pdf

Best regards

kailyn

0 Gokul Koraganji over 2 years ago in reply to Kailyn Chen

TI__Mastermind 19250 points

Hi Kailyn,

I suggest going through the debug guide of DP83867 https://www.ti.com/lit/an/snla246b/snla246b.pdf and perform the checks mentioned in the app note.

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Regards,
Gokul.

Interface

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DP83867CR: some switches can't link and the RX_CLK is unstable