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DP83825I: DP83825I

YOUNG DO SEO
Prodigy 10 points

Part Number: DP83825I

I'm developing an IP camera using the DP83825IRMQR. 

I've been experiencing frequent link downs during camera operation, so I requested a defect analysis of the chip and received the results. The results indicate a short circuit between Pin 10 (TD_M) and GND, and a short between Pin 11 (TD_P) and GND, along with an EIPD error. (See attached file)QEM-CCR-2510-00052_Final report_IDIS.pdf 

This is the circuit diagram for the IP camera currently under development. Please review it to identify any potential issues. Are there any areas that need to be modified?DP83825I schemetics.pdf

  • 0
    TI__Guru**** 183501 points

    Hi,

    Since EOS damage could come from multiple sources. we provided a fishbone diagram listing the potential sources of EOS damage in the QEM report. It would be good to use the diagram as a guideline to find the source of the EOS damage.  

    Under what condition did the failure happen? And do you see the failure on multiple boards or a particular board?

    Can you share the spec on D3 and D4, are these the ESD diodes? 

    I also noticed that solder coverage may not be ideal on the two return units. It looks like only one corner of the thermal pad has solder.

    In the DP83825 datasheet, we recommended to have at least 81% solder coverage. It will be good to x-ray the board to verify that there is sufficient coverage to ensure a proper ground return path. 

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 10 points 
    This phenomenon occurs on some boards, causing a sudden link down during normal operation, leading to chip failure.

I've attached the TVS and line filter specifications. Will this be a problem with the specifications?

    Nichtek_D3271-3R0AKXB_V.3_20190610.pdfWCM2012F2Sf-801-N.pdf
  • 0 in reply to YOUNG DO SEO
    TI__Guru**** 183501 points

    Hi,

    The TVS diode does not provide a transmission line pulse or TLP curve so I can't tell its clamping voltage at Ipp of 8A. The DP83825 MDI Absolute Max Rating is 4V for the MDI lines, so I would find a TVS diode that can provide clamping voltage <=4V at Ipp of 8A to make sure the MDI is not getting damaged by a potential ESD event.

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 10 points

    We currently have a line-to-line TVS installed. However, looking at the DP83825I EVM circuit, we see that the line-to-ground TVS is used (TPD4E05U06DQAR).

    1. If I were to use a line-to-line TVS according to the current circuit, would it be okay to use a material with a Vc value of 4V or less at an IPP of 8A? Can you recommend a TVS material with these specifications?

    2. Should I install a separate line-to-ground TVS, as shown in the EVM?

  • 0 in reply to YOUNG DO SEO
    TI__Mastermind 23251 points

    Hi, 

    We do not have specific recommendations for TVS diodes, but we recommend to use lower clamping voltage that matches our absolute max voltage.
    Line-to-GND TVS diodes will help increase the ESD performance of the system by sending the ESD event charges to the GND instead of dissipating to other transmission lines. 

    Best,
    J

  • 0 in reply to J
    Prodigy 10 points 
    Is there a reason why Vc is presented as the standard when Ipp=8A?
  • 0 in reply to YOUNG DO SEO
    TI__Mastermind 23251 points

    Hi,

    This is the standard per IEC standard when the diodes are characterized.

    Best,

    J