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TMDS361B - Propagation delay time, low to high (tPLH2) exceeding the maximum value.

Kawai
Guru 19775 points
Other Parts Discussed in Thread: TMDS361B

Hello Team,

I have a similar question to my other post about TMDS361B propagation delay time.

https://e2e.ti.com/support/interface/digital_interface/f/130/t/443817

[Question]
In our customer evaluation, tPLH is exceeding the datasheet specification. Is it allowed ?
Is there a required specification for HDMI standard ?

When the device is used in the real application, user would use different types of cables. So, I am thinking that the condition would be different from the tested circuit, Figure 4 and 5. When using with long cables t_PLH would be much longer. Could you please tell me how you could know if the customer tPLH is OK or not ?

Thanks in advance.

Best Regards,

Kawai

  • 0
    TI__Mastermind 23815 points

    Hi Kawai-san,

    Values in this table are recommended values, for precise values required by HDMI we have to look up at I²C specification version 2.1 in standard-mode this is the standard use by HDMI.

    In such specification there are no minimum rise and fall times, but there are maximum values:

    max rise time: 1000ns

    max fall time: 300ns

    There is enough range to have long cables.

    Regards

  • 0 in reply to Moises Garcia
    Guru 19775 points
    Hello Moises-san,

    We greatly appreciate for your support.

    I believe that the values in the table are recommended value for specified condition. So, testing in the same condition, each propagation delay should be inside the range.
    If testing with real application set up using long cable, I understood that the rise/fall time should be lower than the above value. Could you please correct me if my recognition is incorrect ?

    Best Regards,
    Kawai
  • 0 in reply to Kawai
    TI__Mastermind 23815 points

    Hi Kawai-san,

    Having a long cable will increase rise/fall time, this is because you have resistance/capacitor circuit, the long cable will increase circuit resistance leading to longer time to charge/discharge the capacitor, that's why I²C specification has maximum values, not minimum.

    Just to clarify, this parameter corresponds to rise/fall times for I²C to function properly, while the parameter you asked before corresponds to the delay added by TMDS361b.

    Regards