DP83869HM: 1000Base-X implementation

Hi David, 
DP83869 supports media converter mode for 1G and 100M but at fixed speed. the topology you shown should work if the network access point gives out signal detect signal to the PHY somehow so it can establish the link. 
In addition, I suggest using SGMII to copper mode for DP83869 if you do not want to have a separate signal detect signal sent out from the FPGA and it would use the same number of pins. 

Please let me know of your thoughts. 
Best,
J

Thank J again for the comments,

We gonna implement you suggestion and set the PHY in SGMII mode.
Now the board will mount 4 PHYs, therefore space is a challenge.
I have seen in the reference design that the https://www.yageogroup.com/content/datasheet/asset/file/DATASHEET_HX5008NL used.
This Trafo doesn't have its central taps connected. 


I have found one double RJ45 connector with integrated magnetics that would make the board easy but it has its central taps connected! 
 (https://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=2301997-4&DocType=Customer%20Drawing&DocLang=English&DocFormat=pdf&PartCntxt=2301997-4)


So, the question: is it possible to use trafos that have their central taps connected?

Thanks in advance
David

Hi David, 

We typically do not recommend to use magnetics with center taps shorted to keep a good signal quality and keep a good EMC performance. However, we are currently investigating specific ramifications of using center tap shorted magnetics. I will keep you updated, but this may take some time. 

Best,
J