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TMDS181: TMDS181 cascade use

Frank Xiao
Genius 12055 points
Part Number: TMDS181

Hi team,

My customer wants to use the TMDS181 cascade, do we have some test datas for this usage? Will they meet some problems if use the chip like this? Thank you.

BR

Frank

  • 0
    TI__Mastermind 23815 points

    Hi Frank,

    The problem os placing several TMDS181 in cascade may come from DDC and HDCP, not really from TMDS181 redriving/retiming capabilities.

    We recommend using snoop mode to avoid interoperability issues, if the cable is too long you may need other I2C buffers.

    HDCP2.2 checks if the sink is not far away from the source if there are several TMDS181 in cascade there will be some delay especially in retimer mode.

    Could you elaborate about the application?

    Regards

  • 0 in reply to Moises Garcia
    TI__Genius 12055 points
    Hi,


    The customer may not need the HDCP. And they use the chip not becasue the long line.


    They use some MUX chips to distribute the HDMI output. And they use TMDS181 before every MUX chip. So they want to check whether it has problems or not. Thank you.

    BR
    Frank
  • 0 in reply to Moises Garcia
    TI__Genius 12055 points
    Hi,

    The customer's board will have one HDMI splitter after TMDS and have HDCP and DDC driver. So it may not meet the HDCP and DDC problem.
    The customer is worried about the jitter will make the receiver cannot lock after many stages cascade. They need 40 stages cascade at least and may reach 100 stages and every stage is 2m. Can the chip meet the customer's requirement? Thank you.

    BR
    Frank
  • 0 in reply to Frank Xiao
    TI__Mastermind 23815 points

    Hi Frank,

    40 or 100 stages are a lot, and 2m is kind of short.

    TMDS181 can work in redriver or retimer mode, by default, it is redriver with data rates below 1Gbps and retimer with data rates above 1Gbps.

    In redriver mode jitter and skew will be adding up, while in retimer mode jitter and skew is cleaned in each stage.

    TMDS181 can be configured by I2C to retimer mode across full data rate range.

    I recommend opening a HelpMe ticket to further review of this amount of devices in cascade.

    Regards