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DP83TD510E: 100Mbps link when back-to-back RGMII with DP83822

Cyrus Kelly
Prodigy 240 points

Part Number: DP83TD510E

Tool/software:

Hello,

I designed an Ethernet to Ethernet-APL media converter using the DP83TD510E and DP83822 in back-to-back RGMII mode.  It works fine if I use the straps on the DP83822 to force it to 10BASE-Te half/full duplex.  However, I have customers that use the Profinet protocol.  Profinet controllers require a 100Mbps link.  Is there a way to configure the chips to support this?  The Ethernet port would operate at 100Mbps while the Ethernet-APL port would operate at 10Mbps.

If it is not possible to configure these chips to support 100Mbps to 10Mbps, can you recommend an approach to change the design so it would be supported?

Thanks

  • 0
    TI__Mastermind 26315 points

    Hi Kelly,

    We will reach out to you by the end of today.

    --

    Regards,

    Hillman Lin

  • 0
    TI__Expert 8255 points

    Hi Cyrus, 

    Unfortunately, this configuration is not possible. In any media conversion, both link speeds need to be the same, so it is not possible to have 10Mbps on one side and 100Mbps on the other. 

    If the customer required a 100Mbps, they would have to use a 100Mbps Single Pair PHY which does not support T1L.

    Since profinet requires a minimum speed of 100mbps it is not possible to use it in conjunction with a 10Mbps T1L PHY such as the 510. 

    If the customer needs the functionality of T1L, it will not be compatible with profinet. If the customer needs a single pair to CAT5E conversion, another option would be a media converter using the DP83TC812 such as this one.

    Best,

    Vivaan

  • 0 in reply to Vivaan Jaiswal
    Prodigy 240 points

    Hello Vivaan,

    Thanks for the quick reply.

    The customer needs a product that converts from 100Mbps Ethernet on one side to 10Mbps 10BASE-T1L on the other side.  This is something that is done in Ethernet APL Field Switches.  Regular Ethernet switches would have to do it too, supporting 10Mbps devices and 100Mbps devices on different ports.

    I am not familiar with Ethernet switches.  Is there a chip that the ports connect to that does the speed conversion?  If I can figure out how switches handle different Ethernet speeds on their ports, I may be able to apply the same technique to my product.

    Your feedback is appreciated.

    Cyrus

  • 0 in reply to Cyrus Kelly
    TI__Expert 8255 points

    Hi Cyrus, 

    Ethernet switches use a combination of PHYs to delegate multiple network speeds. These PHYs require a processor to efficiently divert the packets without affecting main network speed. This kind of configuration is not possible using PHY to PHY media conversion since PHYs only act as an input to output physical layer medium and does not have any computing capabilities. Because of this restriction, the input and output speeds must match.

    However, there may be a ethernet switch based solution available for this application. TI does not manufacture ethernet switches, only ethernet ICs, but if there is a switch on the market that supports 10Base-T1L for one of the ports, the switch may be able to help with this conversion.

    Best,

    Vivaan