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SN65LVDS9637: Input pin shorting to ground

James Adams
Prodigy 10 points
Part Number: SN65LVDS9637


Tool/software:

Dear TI Support Team,

I hope this message finds you well.

I am reaching out regarding an issue I have encountered with the SN65LVDS9637 differential to LVDS receiver in one of my designs. To provide some context, we have manufactured approximately 20 boards, and two of them have exhibited the same failure: Input pin 1.A is shorted to ground internally within the device.

Details of the Issue:

  • Device: SN65LVDS9637
  • Quantity Produced: 20 boards
  • Failed Units: 2 boards
  • Failure Description: Input pin 1.A is shorted to ground internally

Observations:

  • The data sheet indicates a high ESD rating, leading me to initially assume that ESD damage is not the cause.
  • Both failed units show the same symptom, suggesting a potential systematic issue rather than random failure.

Request for Assistance:

I would greatly appreciate any guidance or insights into potential causes for this issue. Specifically, I am interested in understanding:

  1. Possible manufacturing or assembly processes that could lead to this failure.
  2. Any known errata or common pitfalls associated with the SN65LVDS9637.
  3. Recommended testing or diagnostic procedures to further isolate the cause.

Thank you in advance for your assistance. I look forward to your valuable input.

Best regards,

James Adams

Hardware Engineer  

CACI International

james.adams2@caci.com

  • 0
    TI__Genius 10536 points

    Hi James, 

    Thanks for reaching out. Sorry you are experiencing this issue. There are a few possible causes to this issue (some of which you've mentioned already):

    • Manufacturing defect 
      • These are very rare for something like an input pin shorting to ground. Every single pin on a TI device that is shipped out of a TI factory goes through a continuity/short test at the end of the production cycle before being put in a reel. 
    • Electrical overstress during evaluation/handling
      • This could be caused by either a specific stress test that was performed before the failure was overserved (such as ESD), or there could be something else in the system inducing a surge/overvoltage onto the line inadvertently. Were there any stress tests done to this board prior to the failure observation?
    • Board/other-component issue
      • You could be seeing a short to ground on the line the pin is connected to, but the short current might not necessarily be flowing through the SN65LVDS9637.For example, if you have a TVS diode on the line that gets damaged, that would cause a short circuit. You could also have a stray piece of metal/solder somewhere else on the board that is shorting the line to ground. 

    I don't know of a specific document talking about failure modes, but I would recommend start with this document as an overall guide for designing with LVDS: LVDS Owner's Manual Design Guide, 4th Edition . It includes sections on layout, timing, etc.

    For next steps to debug this issue, I would recommend you do an A-B-A swap if you haven't already; meaning replace the damaged device with a fresh unit on the same board, confirm it is functional, then resolder the old unit back on the same socket to see if the problem still persists. Additionally, I would also recommend putting the damaged device on an evaluation module (EVM) we make to confirm if it is a board/design issue. If you have done all these things already, please share the full part number (with package identifier), schematic, bias conditions, and layout if you can, so I can further assist. 

    Regards,

    Matt