• State TI Thinks Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 33 subscribers
  • Views 402 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DS90UB948-Q1: ESD Contact Discharge test fail

Jesse Lee
Expert 1985 points
Part Number: DS90UB948-Q1

hello

we use DS90UB948-Q1 in our display product.

Both +/-4KV ESD Contact Discharge test are failure, the phenomenon is that the dispay picture appears to flicker.

When we fix the diaplay panel's backlight enable control pin to Level high instead of controlled by the GPIO 1/Pin 8 of 948, Both +/-4KV ESD Contact Discharge test are pass that has no flicker phenomenon.

So we can confirm that this issue root reason is 948's weak ability of anti-ESD in our system.

we have added TVS on the circuit of GPIO 1, but it has no work.

we also add chasis on the PCBA board, but it has no work.

Could you help provide any suggestions on this issue?

Thanks

  • 0
    TI__Intellectual 1565 points

    Hi Jesse,

    Try putting a 100pF NPO ceramic cap from the backlight enable to ground.  If this improves performance but does not fully fix it, try a 1uF X7R ceramic cap.

    Make sure you have sufficient link margin, and optimize the AEQ settings.  This can be done with the TI Analog LaunchPad SW tool and is described here:

    Use the tool to see the "eye" (AEQ settings that allow the SERDES to LOCK), and then change the settings so that the AEQ is set in the middle of the "eye".  Under normal operation, the FPD-Link starts at the minimum setting and increases until LOCK is achieved.

    For the DS90UB948-Q1, the register settings are different than in the app note.

    • 7.3.12.3.2 describes overriding the AEQ floor.  See 7.7.1.47 and 7.7.1.54 for register details.

    Other options

    • Power consumption can increase during an ESD event.  Make sure your power regulators are not browning out during the ESD test.
    • Try a DLW21SZ900HQ2L or similar common mode choke in the link path.
    • Try a 2pF ceramic cap across the differential serial path near the AC blocking caps
    • New link cables that have been inserted less that 10 times perform better

    Mike

     

     

  • 0 in reply to Mike Leister
    TI__Intellectual 1565 points

    Hi Jesse,

    Is there anything else I can do to help?

    Mike