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DP83TC811S-Q1: Searching for PHY/PHYs and questions on Ti 100base T1 PHY

Avner Cohen
Intellectual 380 points
Part Number: DP83TC811S-Q1
Other Parts Discussed in Thread: DP83TC811, DP83TD510E

Hi,

For a new project I would like to get some answer on the following questions:

  1. I need a PHY for Ethernet communication between central unit and up to 16 units.

The application is Avionics and the temperature grade of the PHY need to be at least 125C junction

What is your recommendation of such PHY (PHYs)  which will have long longevity ?

  1. I consider using the Automotive PHY DP83TC811S-Q1 since it has the ability to work on single pair based on the 100BASE-T1 standard. However, since the max length between the units can reach up to 60m~80m and I do not need 100Mbps I thought operating it in 10Mbps.
    1.  In that case, can you say surely what will be the range of the cable the DP83TC811S-Q1 can support ?
    2. If the device is set to 10BASE-T full Duplex  using the BMSR register, does it means it will support 10BASE-T on single pair with the standard cable length of 100m ?
  2. In the data sheet it is written " 100BASE-T1 – IEEE 802.3bw Compliant – OPEN Alliance Qualified – Interoperable With BroadR-Reach and 100BASE-T1 PHYs " What is the meaning of the sentence " OPEN Alliance Qualified " and will keep on interoperability if the rate will be 10Mbps and not 100Mbps ?
  3. Since the product will have a lot of PHYs, in order to reduce the routing I wish to work in SMII mode.
    1. Why this mode is SGMII and not SMII (1000M vs 100M) ?
    2. If I would like to operate the device in 10Base-T and not 100Base-T can I work with SMII/SGMII ?
    3. What would be the rate of the SMII bus when working in 10BASE-T mode
    4. It is written that the clock to the PHY (XI pin 5) is 25M in case of MII / RGMII / SGMII and 50M in RMII mode. Is the 25M still true if the unit works in 10BASE-T and not 100BASE-T ?

 Thanks,

Avner

  

 

  • 0
    TI__Expert 8650 points
    Avner Cohen said:
    What is your recommendation of such PHY (PHYs)  which will have long longevity ?

    You can filter through the product page fore the temperature spec, MII required and all the parameters required for your application.
    https://www.ti.com/interface/ethernet/phys/products.html


    Avner Cohen said:
    I consider using the Automotive PHY DP83TC811S-Q1 since it has the ability to work on single pair based on the 100BASE-T1 standard. However, since the max length between the units can reach up to 60m~80m and I do not need 100Mbps I thought operating it in 10Mbps.

    DP83TC811S operates only in 100-Mbps. No 10-Mbps is supported.

    Avner Cohen said:
    In the data sheet it is written " 100BASE-T1 – IEEE 802.3bw Compliant – OPEN Alliance Qualified – Interoperable With BroadR-Reach and 100BASE-T1 PHYs " What is the meaning of the sentence " OPEN Alliance Qualified " and will keep on interoperability if the rate will be 10Mbps and not 100Mbps ?

    Here is an app note that will describe about the Open Alliance spec for DP83TC811, also available on the product page:
    https://www.ti.com/lit/an/snla293/snla293.pdf?ts=1669676047066&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FDP83TC811S-Q1

    This device supports only 100-Mbps.

    Avner Cohen said:
    Since the product will have a lot of PHYs, in order to reduce the routing I wish to work in SMII mode.

    SMII mode is not supported by this product. Currently TI do not offer any PHYs that supports SMII interface.

    Hope this helps.

    Regards,
    Rahul

  • 0 in reply to Rahul
    Intellectual 380 points

    Hi Rahul,

    Thanks for the rapid answer.

    I saw that device speed selection is always 100-Mbps in reg 0x0000 even though the register 0x0001 show option for the 10base -T. Ok thanks !

    Well, if so, the 100base -T is defined to support 15m cable. Do Ti tested the PHY with longer distance ? what is the longest cable that is verified with the DP83TC811S-Q1 please?

     Thanks,

      Avner

  • 0 in reply to Avner Cohen
    TI__Expert 8650 points

    Hi Avner,

    DP83TC811S will definitely support 15m cable, and I do not think it will reach the lengths as per your requirements.

    There will be multiple factors involved for achieving longer length, it can be the cable quality, software adjustments etc. I would recommend to perform cable length tests using our evaluation modules.

    If you are looking for a 100BASE-T1 PHY, we would recommend using DP83TC812.

    If you want a longer reach PHY, I would recommend to use DP83TD510E which is a 10BASE-T1L PHY and it can support up to 2km length, but it is not an automotive PHY as per your requirement.

    Regards,
    Rahul