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TS3DV642EVM: Differential Impedance for HDMI2.0 Compliance Test

Sadanori Kato
Guru 36510 points
Part Number: TS3DV642EVM
Other Parts Discussed in Thread: TS3DV642

Hi,

Our customer measured the differential impedance for TS3DV642EVM by using TDR(Time Domain Reflectometry) measuring equipment.
Unfortunately, TS3DV642EVM cannot pass HDMI2.0 compliance test HF2-4 since the measured impedance exceeds the standard value.
So, Can TS3DV642 pass it ?
Could you please share the measurement data to us if you have it for the differential impedance ?
In addition, please give me an email to my email address since I would like to share the detailed information to you.

Best regards,
Kato

kato-s@clv.macnica.co.jp

  • 0
    TI__Mastermind 45370 points

    Kato,

    We did not design the TS3DV642 to pass the HDMI 2.0 compliance test and do know that a customer has failed HDMI 2.0 compliance testing when they interfaced their system with the TS3DV642 EVM.  However, we have had customers successfully pass the HDMI 2.0 compliance test when they have carefully designed their signal chain with the appropriate impedance matching using the TS3DV642.

    Also wanted to make you aware of another post related to HDMI compliance testing highlighting a potential issue we have seen using the TS3DV642 failing a line item in the compliance test and how to avoid it.

    Thank you,

    Adam

  • 0 in reply to Adam Torma
    Guru 36510 points

    Hi Adam-san,

    Thank you for your information.

    Could you please allow me to discuss offline since I would like to know how to design their signal chain with the appropriate impedance matching using the TS3DV642 ?
    I will send you our customer test waveform information material.

    Best regards,
    Kato

  • 0 in reply to Sadanori Kato
    Guru 36510 points

    Hi Adam-san,

    There is mentioned in TS3DV642EVM user's guide that all four differential pairs on TS3DV642EVM are impedance matched to a 100Ω differential.
    However, TS3DV642 has an impedance exceeding 115 Ω at the peak.
    How have your customers improved the differential impedance ?
    Honestly, it is not reasonable even if passing it since TS3DV642 in itself should be managed with 100Ω.

    Could you please give me your advice since I should inform our customer of the workaround as soon as possible ?

    Best regards,
    Kato

  • 0 in reply to Sadanori Kato
    TI__Mastermind 45370 points

    Kato,

    The differential impedance is highly dependent on several factors in your PCB design.  Here are some good reference materials discussing these different layout options and how they can effect the performance of the high speed system.

    High-Speed Interface Layout Guidelines

    High-Speed Layout Guidelines

    The impedance will also very with frequency so we have s-parameter model for the TS3DV642 so you can see the characteristic impedance of the device as at the specific frequency you are attempting to optimize your impedance matching.

     

    Thank you,

    Adam

  • 0 in reply to Adam Torma
    Guru 36510 points

    Hi Adam-san,

    Thank you for your advice.

    I will check these materials.

    Best regards,
    Kato