DP83848Q-Q1: Dual PHY configuration

Mitchell

Part Number: DP83848Q-Q1
Other Parts Discussed in Thread: DP83TC811R-Q1

Hi Team,

My customer is looking at using 2x DP83848Q-Q1's for a dual 100BASE-T1 PHY architecture, both of which will be connected to a TMS570 MAC for redundancy.

From our research, it sounds like using 2 of these IC's is required as the only dual port solution only supports 100BASE-TX and not 100BASE-T1. We have a couple questions based on this type of implementation:

How would we route the MII/RMII TX/RX lines from one MAC to two PHY devices?
If we route in a star configuration or a daisy chain configuration for each RX/TX line, would there be issues with reflections due to stubs (how does termination work)?
Are there additional constraints on placement and layout?

Thanks,
Mitchell

over 6 years ago

0 Hung Nguyen92 over 6 years ago

TI__Expert 5670 points

Hi Mitchell,

Not sure I understand your question. DP83848 cannot be used for 100Base-T1 architecture.

There is dual PHY DP83849 which can do internal port switching to support redundancy.

If there are two PHYs and one MAC, external switching has to be taken care of.

Regards,

Hung Nguyen

0 Mitchell over 6 years ago in reply to Hung Nguyen92

TI__Expert 4915 points

Hi Hung,

I apologize for the confusion. Basically our question is in follow up to this related post: https://e2e.ti.com/support/microcontrollers/hercules/f/312/t/777421 but specifically in regards to using 2 PHYs.

My customer is trying to figure out how to design a dual-port 100Base-T1 architecture to support redundancy. I guess the correct part would be something such as the DP83TC811R-Q1 since it supports 100Base-T1.

Assuming a part like this is used, do we have any documentation on how to implement the external switching?

Thanks,
Mitchell

0 Hung Nguyen92 over 6 years ago in reply to Mitchell

TI__Expert 5670 points

Hi Mitchell,

Unfortunately, there is no available document about using external switching.

You can search for low Ron, SPDT mux to use for this application.

Regards,

Hung Nguyen

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DP83848Q-Q1: Dual PHY configuration