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DP83826I: silicon bug

max Haymann
Prodigy 20 points
Part Number: DP83826I

Hello,
I am writing to find out how TI deals with bugs on the silicon if they are not recognised in time. Are they recalled? Because we have found a Bug witch only can be explained by a bug on the Silicon.
Background: we are using the DP83826IRHBR (Ethernet PHY) in one of our designs. In the process, we came across a bug in one version that is related to the PHY. It concerns the strapping pin 0, which defines which duplex mode is used (full or half duplex). 
The bug: PCB revision 1 negotiates the full duplex mode while the other revision 2 negotiates the half duplex mode, although the PHY is wired exactly the same. We have even swapped the PHY ICs between the two revisions with the result that rev1 now negotiates half duplex and rev2 uses full duplex.
The only reason we can think of at the moment is that there is a bug on the silicon of the PHY in one batch that reverses the polarity of the strapping pin0. More specifically, we believe that the PHY IC batch placed on rev1 has the described bug, because it does not behave as described in the data sheet for the strapping pin 0.

Print on PHY IC used in rev1: 826I    TI 168     AEXJ G4 (see picture)

Print on PHY IC used in rev2: 826I    TI 298     A4GF G4 (see attached picture)

I would be very happy about a possible explanation for this problem. If you need further information, I will be happy to provide them.

With kind regards,

Max Haymann

 

  • 0
    TI__Mastermind 39815 points

    Hi Max,

    The behavior that you are describing looks to be in line with revision changes made between revisions of DP83826. The previous revision of the device had a strap setting of '1' as a full duplex, while now it is at half duplex for that same strap pin value. The best recommendation I can give is to adjust future designs towards what is reflected in the datasheet as that will be the behavior of any devices that is obtained via TI.com.

    Sincerely,

    Gerome

  • 0 in reply to Gerome Cacho
    Prodigy 20 points

    Hi Gerome,
    Thank you very much for your quick reply. But there are still some points I am not clear about.
    Firstly, I always thought that the revision history in the datasheet only tracked clarifications in the datasheet itself and not bug fixes/changes on the silicon. I am now wondering how to distinguish between updates in the datasheet made because the previous datasheet version was incorrect/unclear and those made because of a new silicon version. I would expect a change in the silicon to be communicated differently than a small change in the datasheet. If I am missing something here, please let me know.
    Secondly, is there only one silicon update of the DP83826 or are there more?
    Lastly, can you tell me which batch numbers belong to which silicon version? Because we still have some of these ICs in stock, so it would be very important to know how to set the strep pin for them.

    Sincerely,

    Max

  • +1 in reply to max Haymann
    TI__Mastermind 39815 points

    Hi Max,

    There was a PCN for this revision change, and a copy of that announcement can be found here. Regarding datasheet, the document will have the reflection of the most up to date behavior of the device; once there was a revision change, the datasheet was updated to reflect the current revision.

    The PCN will also have details as to how to distinguish between ICs. In addition, Reg 0x3[0] can also indicate the difference.

    There have only been two version of the part; Rev A and Rev B.

    Sincerely,

    Gerome