Connecting X550-AT 5th channel to discrete magnetics

[Aktus]

Hello,

I need help in the detailed schematics for connecting the 5th channel to discrete magnetics. From datasheet I learned that pair D termination should be 300 Ohm (instead of usual 75 Ohm) but it looks like that more components and connections are required. Can anyone give me the details?

An example schematics is attached. There's also a layout shapshot from X550 datasheet attached - what are the components marked with red arrows? Are they all 300 Ohms resistors or something else?

Am I right that CMD_DN net should be connected to the 'common' point of the termination circuit while CMD_DP net is connected to the center of a T-like 300 Ohm resistor network (with its endpoints connected to DD+, DD- pins of the connector jack and MDI4CT pin of the transformer)? Should CMDSPCT pin be left floating?

A detailed reply will be very much appreciated.

Regards,

Dmitry

[Caguicla_Intel]

Hello Dmitry,

Thank you for posting in Intel Ethernet Communities. 

Please share the following information that would us to determine which department would be best to assist you.

1.) Is the X550-AT controller embedded on your motherboard? 

2.) Can you share more information regarding your setup? Are you designing or customizing your own board?

Looking forward to your reply.  

We will follow up after 3 business days in case we don't hear from you. 

Best regards,

Crisselle C

Intel® Customer Support

[Aktus]

Hello Crisselle C,

Please find the answers below:

1) Yes, an X550-AT controller is embedded on a motherboard.

2) I'm designing my own board. A c620 series chipsetb will be used from host side, a connection to cloud will be with the help of duiscrete transformers, S558-10GB-10 (Bel Fuse) are likely.

Feel free to ask more questions if any.

Kind regards,

Dmitry

[Aktus]

Actually, I have one more question regarding X550-AT: Is VCCA (1.0 V) an externally applied voltage or is it an internally generated reference? If it should be applied externally, what is its current consumption and whre is its "place" in the powering sequence?

Unfortunately, could not fiind anything about it at the datasheet.

Regards,

Dmitry  

[Caguicla_Intel]

Hello Dmitry,

Appreciate your swift reply. 

Since you are designing your own board, please be informed that your query will be best answered by our Embedded Connectivity Support team. We will help you to move this post to the designated team for further assistance. 

Feel free to contact us if you need assistance from Ethernet support team.

Best regards,

Crisselle C

Intel® Customer Support

[CarlosAM_INTEL]

Hello, @Aktus:

Thank you for contacting Intel Embedded Community. You should follow the guidelines stated in section 13.2.3, on pages 1139 of the Intel® Ethernet Controller X550 Datasheet document # 333369. You can find it when you are logged into your Resource & Design Center (RDC) privileged account on the following website:

https://cdrdv2.intel.com/v1/dl/getContent/333369

You should fill out the RDC Account Support form to process your account update request or report any inconveniences with the provided site. You can be found on the following website:

https://www.intel.com/content/www/us/en/forms/support/my-intel-sign-on-support.html

Best regards,

@CarlosAM_INTEL.

[Aktus]

Hello @CarlosAM_INTEL

Unfortunately, this won't help me as I've already read this document before asking a question here. And the connection details were not clear. But now I've got a Reference Design (doc #557650) and so I feel better.

But anyway, I still would be very thankful if you could clarify the components I outlined with red circles (please see attachment to my first message).

At ref. design the positive pin of the 5th channel (at cloud side, pin 17 of the transformer) is connected to the center point of the 4th channel (D-channel), pin 21, through a zero resistor while the negative pin of the 5th challel (transformer's pin 16) is connected to the 'common' node of the Bob Smith's termination. The 5th center point is left floating thus. 

But at a layout snapshot from datasheet (#333369) I see some additional components under LAN jack connecting  MDI5+ to both MDI1+ and MDI1- - what are they? Are they optional 0 Ohm resistors or something else? What is their purpose?

Kind regards,

Dmitry

[CarlosAM_INTEL]

Hello, @Aktus:

Thanks for your reply.

We want to address the following questions to better understand this situation:

Could you please list the sources that you have used to design the project related to this situation?

Could you please clarify if it has been verified by Intel?

We are waiting for your answer.

Best regards,

@CarlosAM_INTEL