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TMDS361B - HDMI Compliance Testing

Kawai
Guru 19785 points
Other Parts Discussed in Thread: TMDS361B

Hi,

Our customer will use TMDS361B in their application. I have question about HDMI compliance testing.

In the datasheet it says,

"For HDMI compliance testing (TMDS termination-voltage test), the clock-detect feature should be disabled. In this mode, the terminations on the TMDS input data lines are always connected when the port is selected."

If you disable the clock-detect feature, it seems the compliance testing is meaningless. Is this acceptable in the compiance testing ?

Our customer is worrying that they may not be able to pass the test.

Please give us TI opinion.

Best Regards,
Kawai

  • 0
    TI__Guru* 76130 points

    Hello Kawai,

    The clock-detect should be disabled only for the "TMDS-termination voltage test", this is just one of the several compliance test steps.

    I don't understand why they say that the compliance test is meaningless when you disable the clock detect feature.

    Can you elaborate more/

    Regards.

  • 0 in reply to Elias Villegas M.
    Guru 19785 points

    Hi Elias-san,

    Cusotmer thinks that compliance test should be tested in the normal operating condition, which means that disabling clock detect function would not be the normal operating condition.

    They doubt that testing in unusual condition could pass the compliance test.

    Is it permitted to turn off the clock-detect function in the "TMDS-termination voltage test", in the compliance test ?

    Best Regards,
    Kawai

  • 0 in reply to Kawai
    Guru 19785 points

    Elias-san,

    Could you please help us on this item ? We need your advice.

    If their system cannot pass the compliance test with clock detect function enabled, doesn't that mean same failure would occur in the market ?

    Best Regards,
    Kawai 

  • 0 in reply to Kawai
    TI__Guru* 76130 points

    Hello Kawai,

    we are still investigating this, we will have an update soon.

    Regards.

  • 0 in reply to Kawai
    TI__Guru* 76130 points

    Hello Kawai,

    I've been looking into this and I have the answer:

    The HDMI Compliance test specifies for "TMDS Termination Voltage" test that the source must be disconnected from the sink in order to measure the voltage at the TMDS lines.

    The clock-detect feature is a special feature of our device, it has nothing to do with the HDMI spec. If the clock-detect feature is not disable, then when the Source is disconnected to perform the test the TMDS361B will enter in a power saving mode and the test will not be possible.

    Regards.

  • 0 in reply to Elias Villegas M.
    Guru 19785 points

    Hi, Elias-san,

    Thank you very much for the information. I understand.

    Best Regards,
    Kawai