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Original question:

DP83867E: Phy unconnected pins

DP83869HM: Interface between SFP (fiber optic) and 1000Base-T

Gerald
Genius 9570 points
Part Number: DP83869HM
Other Parts Discussed in Thread: DP83869

.Hi Experts,

Our customer has a doubt about one of our components: DP83869HM

He want to use it as an interface between SFP (fiber optic) and 1000Base-T. He saw that it has an RGMII interface, but he doesn't want to control it from a MAC, he just wants to use it to transform SFP signals to 1000base-T and connect this signal (with other signals) to an Ethernet switch. Do you think it is possible to leave the RGMII port in DP83869HM without a connection?

We saw another component, DP83849, and we think this device could work without a MAC interface, but this device is used only for 10/100Base-T and the customer needs 1000Base-T. Maybe if you could recommend another way to have an SFP (fiber optic) to 1000Base-T interface, we would appreciate it (in case DP83869HM is not the one). Thank you.

Kind regards,

Gerald

  • +1
    TI__Mastermind 39845 points

    Gerald,

    DP83869 can do 1000Base-FX to 1000Base-T. Please see table 12 in datasheet for bootstrapping settings.

    Sincerely,

    Gerome

  • 0 in reply to Gerome Cacho
    TI__Genius 9570 points

    Hi Gerome,

    Please see below for our customer response:
    "Thank you very much for your response.
    Maybe I need to explain my design better. In my project, I am going to install a SFP for Optical fibre. I would like to transform the signal from this SFP (I assume it is SerDes) to 1000Base-T, in order to connect this 1000Base-T to a Ethernet switch (since my project is going to include SFP and Ethernet connectors). Please, see the attached picture "Schema.jpg".

    So, according to that, how I need to set the OPMODE bits (Table 60)?
    Also, if I use DP83869, I would need to use a MAC to send data to the DP83869 in order to configure the registers, am I right? Is there no option to configure the DP83869 without a microcontroller/FPGA/Soc? I am asking this because I would like to use DP83869 simply as a bridge without communication with the SoC in my board.
    Maybe you have another model which fits better with my application.
    Please, if you have any doubt, do not hesitate to ask me."

    I hope you can help us further. Thank you.

    Best regards,

    Gerald

  • +1 in reply to Gerald
    TI__Mastermind 39845 points

    Hello,

    For this configuration (Fiber to Copper), please ensure Reg 0x6E[11:9] = 0x4.

    You may use bootstraps to configure if there is not other requirement to check/modify registers.

    Sincerely,

    Gerome

  • 0 in reply to Gerome Cacho
    TI__Genius 9570 points

    Hi Gerome,

    Thank you very much for your answer.

    Our customer thinks he is going to use the next configuration (see attached picture Schema_v2.png), but have some doubts:

    Below are his concerns:
    - Do you think is this the correct configuration?
    - In the DP83869 with 1000Mbps Media converter configuration, would I need magnetic transformers between the DP83869 and the Switch or they are included in the DP83869?
    - In the DP83869 RGMII to SGMII configuration, I assume this communication is bidirectional from Switch to SoC and viceversa, right?
    - I need to configure the Switch and the two DP83869 devices. Could I use the MDIO and MDC lines configuring different PHY addresses using the bootstraps without any problem?

    Thank you very much in advance.

    Best regards,

    Gerald

  • 0 in reply to Gerald
    TI__Mastermind 39845 points

    Hello,

    In media converter mode, please include transformers on DP83869's MDI connection. Please see datasheet for required parameters and connection diagram for DP83869.

    In SGMII/RGMII bridge mode, communication is bi-directional.

    To program multiple devices, having different PHY addresses using bootstraps would be the correct implementation.

    Sincerely,

    Gerome