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SN75DP130: 10% of parts in production fail to initiate video after power up

Kennon Conrad
Prodigy 30 points
Part Number: SN75DP130

This is a continuation of #CS0522713 that was initiated by our contract manufacturer but that thread has been locked by TI and our contract manufacturer has requested help in solving the problem from us (the designers/owners of the design).

At the end of #CS0522713, David Liu asked "is there a way you can change such that the HPD_SNK goes high after 3.3V is stabilized?"  I would like to understand why this is necessary.  I will modify our circuit to add this functionality as a test but expect this should not be a problem.  Our device is a source and we expected we should be able to directly connect a powered video monitor to our unpowered device (the SN75DP130 output/sink signals), power our device on, and expect to get video.  So we would like to understand if and why this is an expected operational failure of the SN75DP130 before modifying our product to avoid these failures.

As mentioned in the previous thread, hot plugging works reliably and we have no reason to suspect any problems with the cabling or connectors.  This has been tracked down to failures of the SN75DP130 that are fixed by replacing the SN75DP130.

  • 0
    TI__Guru**** 151675 points

    Hi,

    There is a HPD controller in the DP130. With HPD_SNK driving high before power up, couple of flops inside HPD controller can initialize to a wrong state, resulting in not producing the correct internal EN signal to the DP130.

    This is why I want to see with a failing DP130, if you change the HPD_SNK such that HPD_SNK goes high after VCC, whether the failing DP130 now starts to work correctly.

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 30 points

    Thanks for the quick reply, David.  I will modify one of the failing circuits returned from the contract manufacturer.  It may take a few days as I may need to order a power monitor chip to keep the HPD_SNK low until after power-on.

  • 0 in reply to Kennon Conrad
    Prodigy 30 points

    Hi David,

    I found a power monitor chip in our lab and reworked the failing circuit such that the HPD_SNK from the display is going into the power monitor's PB_RST' input and ran the power monitors RST' output to the SN75DP130's HPD_SNK input.  This holds off the HPD_SNK signal going high until power has settled and a display is connected.  Now the video output to the display is configuring and working as expected.

    Before we decide how to proceed to fix this problem, can you answer the following questions?

    Does TI have published errata about the incorrect HPD controller initialization?

    Are there any pin compatible alternatives that do not have this problem?

    Does TI have any plans to fix this problem?

    Best Regards,

    Kennon

  • 0 in reply to Kennon Conrad
    TI__Guru**** 151675 points

    Kennon

    There is no published errata on the HPD controller initialization since the issue does not happen on every DP130.  

    Unfortunately we do not have another pin-to-pin part and there is no plan to fix the issue.

    Thanks

    David