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DP83825I: DP83825IRMQR : Device only working in 10Mbps

Amal A G
Prodigy 40 points

Part Number: DP83825I

Hi, 

we have used the DP83825IRMQR part in one of our device requiring 10/100Mbps network connection.

We faced the below mentioned issue in 2 out of the 30 numbers of PCB developed by us with this PHY IC . Attaching the schematics of the design.image.png

Issue : 

  • The device was not able to function in the 100Mbps mode.
  • We used the same firmware and the same support accessories for testing ( laptops , ethernet cables) as in the working boards.

Observations : 

  • The device link is re-established and the works properly when forced to 10Mbps mode, but not working when forced to 100Mbps mode.
  • The power sequence , voltage levels and reset sequence has all been validated in the boards and the parameters seems to be in accordance with the recommended values. 
  • The clock signals were probed and found to be good and well at 25MHz
  • We tried changing the oscillator as mentioned in this forum : but was not successful. - https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1588099/dp83825i-unable-to-establish-100mbps-link-with-dp83825i-ethernet-phy
  • We tried loopback test in all the modes ( from MAC till the ethernet cable) -  All the loopback results showed success in the 100Mbps link.
  • Reset timing and tuning was tried out by introducing additional delay -  did not resolve the issue.
  • Tried swapping the PHY IC between a working and non working board - the issue still repeats ( the working board turned non working ) ; hence proving that the issue was within the PHY IC )

 

We were able to resolve the issue when the non-working IC was replaced by a fresh PHY sample.

 

Please share your comments on the same.

 

 

 

  • 0
    TI__Mastermind 33655 points

    Hi Amal,

    Since the fail follows the IC, it could be that something is causing these units to fail. I have a few questions to help determine this:

    • Are you performing any stress testing on the boards? (EFT, ESD, ...)
    • Were these 2 units failing originally or did they start failing after a certain point?
    • What is the link partner in these tests? 
    • What cable length is used?
    • Do you notice any other symptoms from the failing ICs?
    • Can you provide a register dump of a failing IC vs a working one in the link up condition? 

    The schematic looks ok from the image you've shown, though this does not show the full MDI path. I recommend evaluating your schematic with the DP83825 schematic checklist. You can use the 'pin wise checklist' tab in this document to look for discrepancies from our recommendations.

    Best,

    Shane