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HD3SS215 for 1:2 simultaneous transmission

Ed Walker
Prodigy 5 points
Other Parts Discussed in Thread: HD3SS215, TMDS181

Hello High Speed Interface forum:

HDMI 2.0/DisplayPort 1.2a, 6.0 Gbps 2:1/1:2 Differential Switch does a 1:2 scenario.
I need it to output an HDMI to BOTH channels simultaneously.
In this case it may be referred to a REPLICATOR.

Can the HD3SS215, or any other TI device perform this function?

Thank you.

  • 0
    TI__Mastermind 23815 points
    Hi Ed,

    This device can't work as a replicator, in the case it could drive the two outputs at the same time you would have a problem because you would have two 50ohm resistors in parallel from HDMI sink terminations. Besides, signal integrity will be highly impacted because of the two paths.
    You may try placing HDMI source, then two paths to two TMDS181, this paths should be very short, thwn you will have two new HDMI 2.0 signals.
    Just connect one DDC channel to "master"display, both displays would have the exact same video. This application won't support HDCP.
    This is not a tested application you may try it at your own risk.

    Regards
  • 0 in reply to Moises Garcia
    Prodigy 20 points

    Hi Moses,

    I may miss something on your answer, but if I take a look at TMDS181 datasheet on page 1 and 15 I spot a problem as you said with 50 ohm resistors in parallel at the input ports of TMDS181: if I put two ICs sharing the same HDMI source, will I have the 50 ohm resistors actually in parallel? Or are you assuming something in particular for the HDMI source signal input?

    Thank you,

    Regards

  • 0 in reply to Matteo Conti
    TI__Mastermind 23815 points

    Hi Matteo,

    Think in signal IN_D2p from each TMDS181, you will connect the two pins to the same D2 from HDMI source.

    Each IN_D2p will have a 50 ohms resistor to Vcc(3.3V), so, each resistor shares the two terminations, on one side they connect to D2 from HDMI source, on the other side they connect to Vcc.

    D2 from HDMI source will sink 10mA, this current will be split in half for each resistor, so, each resistor will have 5mA.

    The voltage drop in each resistor would be around 250mV if there are more losses in the channel this voltage will be even lower.

    Again this is not a tested application, the customer may try it at its own risk.

    Regards