DP83869HM: Link down/link up for Gigabit and 100 Gigabit transmissions

Hi Kailyn,

Thank you for sharing in the information. One of the hypothesis from reading your scenario is the the signal quality is not really good causing the PHY degrade the speed.

Here are couple questions I would like to ask:

• When you said force PC to 1000Mbpas and 100mbps mode. How did you force the speed?
• If possible, could you share the schematic on the MDI side for us to take a look? We also have schematic checklist hope this is useful for you.4666.DP83869_Schematic_Checklist (public).xlsx

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Regards,

Hillman Lin

Hi Hillman,

Thank you very much for your reply.

Hillman Lin said:

When you said force PC to 1000Mbpas and 100mbps mode. How did you force the speed?

He set the link speed by PC  side, please refer to the below  setting to force 100Mbps full duplex.

The schematic is  as this:

Best regards

Kailyn

Hi Kailyn,

From your MDI communication, I did not see a DC isolation between PHY and RJ45 connector. Could you following the schematic recommendation on MDI lines?

We also have schematic checklist for reference:

4336.DP83869_Schematic_Checklist (public).xlsx

May I also ask what is your value on the following resistors?

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Thank you,

Hillman Lin

Hi Hillman，

Thank you very much for your reply.

Hillman Lin said:

I did not see a DC isolation between PHY and RJ45 connector.

The customer used the RJ45 which  is integrated isolation.

Hillman Lin said:

May I also ask what is your value on the following resistors?

It is 3.9ohm. 

Best regards

kailyn

Hello,

Hillman is OoO today, and will look to respond on Monday when he returns.

Sincerely,

Gerome

Hi kailyn,

May I ask what is the usage of 3.9ohms on the MDI lines. If possible, could customer try to remove those resistor and see if that help with the 1Gbps performance. These resistor might effect the impedance matching of the transmission line and degrade the signal quality.

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Regards,

Hillman Lin