DP83869HM: use for MAC to MAC interface with RGMII to SGMII

Hi, 

Please refer to the below FAQ:
https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1008811/faq-dp83869hm-dp83869-in-bridge-mode-to-connect-two-macs?tisearch=e2e-sitesearch&keymatch=dp83869%252525252525252520bridge%252525252525252520mode%252525252525252520mac#

Best,
J

Hi J,

There is a follow-up query, can we connect below TI PHY copper MDI Interfaces without using transformers and still use at 1G speed
DP83867IR, DP83869HM

Is there any application notes available for 1G Copper PHY MDI interfacing without transformers.
Please let us know if there is any other optimal working solution.

 PFB snippet, for understanding the requirement..

Hi Karthik,

Theoretically, that is possible by putting a 33nF decoupling capacitors. However, we do not recommend this design for 867 because it is known to cause CRC errors in the packets. We recommend the customer to use 869 if they will pursue this design.

Best,

J

Hi J,
Do we have any app note or test results for transformer less 1G application with DP83869HM?

Hi Kartik, 

Unfortunately, we do not have an app note for transformerless 1G application. 
We only have this FAQ on E2E:
[FAQ] TI Ethernet PHY Capacitive Coupling (Transformerless Operation)

Best,
J

Hi J

Thanks for the e2e FAQ.
Can we skip the common-mode filtering (since both PHYs are on the same GND) and just use four of small pulse transformers like this.

Only single transformer between 2 chips. Whether below connection can work.

Transformer MPN ALT3232M-151 make: TDK

Hi Kartik, 

You can use four small transformers, but the transformer you mentioned does not fit our recommendation on both insertion loss and inductance. Below is the specification for our recommended magnetics:

Or, please refer to Pulse HX5008NL specifications. 

Best,
J