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TMS320F28388D: Using PHY DP83848 with F2838XDZWTS

Michael Wohl
Prodigy 240 points

Part Number: TMS320F28388D
Other Parts Discussed in Thread: DP83640, DP83848J

Hello,

We are currently using the DP83640 PHY with the F28388D Processor.

Due to supply chain issues we are designing in a different PHY.   Our CPU and processor are on a custom SOM module that plug into a number of custom carrier boards used in a variety of our products.   So our preference is to choose a PHY that is compatible with the (current mode) magnetics that is on those existing application carrier boards.   

Our choice (based upon today's view of distribution and supply) is TI's DP83848J PHY.   Before we purchase a large supply of these PHY's, we have a few questions:

  • Has this PHY been used with the F2838X processors and if so, are there any known issues/concerns about a new design-in?
  • If it has not been used, should it be compatible and again, any concerns?
  • Any reason to expect FW changes and/or customization of the register set on our end when moving to this new PHY?
  • We do see that DP83848 part differs from the DP83640 in that it does not have an interrupt output pin.    Is this a concern from your perspective?   We are thinking it is a no-issue as we use this as a power down functionality rather than an interrupt.   

As always, we appreciate your help with this.

Thanks

Mike

  • 0
    TI__Mastermind 19250 points

    Hi Mike,

    Please find my responses below.

    I am not aware if DP83848 is already used with F2838C processors, although I don't see why it shouldn't work.
    Firmware changes might be required as DP83640 and DP83848 don't have a compatible register set.
    Also, does the application need Time Synchronization? If so, we don't another device which supports Time synchronization.

    If you are looking for a new design, why not do with DP83826, our latest 10Base-Te/100Base-Tx PHY?
    Can you please share a application diagram (along with link partner and protocols used) so that I can check if DP83826 will be compatible?

    --
    Regards,
    Gokul.

  • 0 in reply to Gokul Koraganji
    Prodigy 240 points

    Hi Gokul,

    Thank you for the quick reply.

    Our first thought was to use the DP83826.  However it seems to be a voltage mode magnetics interface and we believe not compatible with the integrated magnetics of the connectors on our application carrier boards.

    As I mentioned in the posting, the PCBA with the delfino and PHY is a common SOM Module that plugs into a different carrier  board for each of our different applications and/or products.   The carrier board has the connector with integrated magnetics.   Below is a basic diagram

    The POE connector with integrated magnetics that we are using (on the application carrier board) is Pulse JKM-0201NL which looks like this:

    My understanding is that the above magnetics would be incompatible with the DP83826?   The connector has common center tap (pin-2) for both TX&RX paths and the carrier board pulls it up to 3.3V.

    Also, we do not use time synchronization.   The DP83640 was initially chosen because of supply chain issues.   In our application, we use a 100MBit TP connection and commonly stream large data sets at >>30Mb/s

    I appreciate you looking at this.  Let me know if you need more info, and/or if the 83826 can be made to be compatible with the magnetics as used on existing boards.   Or if there is another PHY that I am not seeing is available that would be a better choice.

    One other question.  If we cannot use the 83826, then back on the DP83848:   Obviously this part has been in production for sometime.  It still shows "ACTIVE" with no mention that it is not for new designs.   Any feedback on this?

    Thanks again,

    Mike

  • 0 in reply to Michael Wohl
    TI__Mastermind 19250 points

    Hi Mike,

    Since the design needs to be modified, can we remove the center tap if DP83826 is used?
    Also, if DP83826 is used, we need to make sure that the link partner supports 10Base-Te and not 10Base-T.

    DP83848 is also recommended for new designs along with DP83826. I mentioned DP83826 as my guess is that the supply of DP83826 will be better in the next few years and DP83826 also has better EOL compared to DP83848. You can check with your local sales team/FAE to see if my guess is correct.

    --
    Regards,
    Gokul.

  • 0 in reply to Gokul Koraganji
    Prodigy 240 points

    Hi Gokul,

    Modifying the center tap is  unfortunately complicated across multiple board designs and the existing stock.

    I am sure you are right that the 83826 will ultimately be a better/future choice supply chain wise.   Then again, the supply is nothing but unpredictable right now!

    I appreciate your quick response.

    Thanks again,

    Mike