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TMUXHS4612: Lane and Polarity Swapping

Dan Rechichi
Prodigy 70 points
Part Number: TMUXHS4612
Other Parts Discussed in Thread: TDP2004, TMUXHS4512

Tool/software:

Hi,

Does TMUXHS4612 support lane swapping? e.g. swap D0A with D3A.

Does TMUXHS4612 support polarity swapping within a pair? e.g. swap D0+A with D0-A.

  • 0
    Prodigy 70 points

    The context is that I'd like to connect 2x TMUXHS4612 back to back, and depending on the select pins, there will be redrivers or level shifters in between.

    Lane and polarity swapping would allow me to keep both on the same layer, and free up routing space for other things.

  • 0 in reply to Dan Rechichi
    TI__Mastermind 35638 points

    Hi Dan,

    Yes, the TMUXHS4612 will support both. The pin names can almost be thought of as recommendations, but the reality is that you have flexibility to use the mas you want, as long as you don't violate the voltage and current ratings.

    -Rami

  • 0 in reply to Rami Mooti1
    TI__Mastermind 35638 points

    One extra note, when cascading back to back like you are, just be aware that your parasitics will double. We have a couple app notes on the affects:

    Test Report for Cascade Analog Multiplexers

    Designing with Multiple Multiplexers in Series: A Guide to Cascading Multiplexers

    -Rami

  • 0 in reply to Rami Mooti1
    Prodigy 70 points

    Thanks Rami,

    Would redrivers like TPD2004 fix/improve the parasitics issue?

    1x of the TMUXHS4612 muxes would still be an issue since it's at the end of the bus, but I can place the redriver just before.

    Kind regards,
    Dan

  • 0 in reply to Dan Rechichi
    TI__Mastermind 35638 points

    Hi Dan,

    Yes, redrivers should help! 
    I'm looping in the proper team to help find the correct redriver or confirm if the TPD2004 is the correct device. They may need more information about the type of signal you are driving though.

    Thanks,
    Rami

  • 0 in reply to Rami Mooti1
    Prodigy 70 points

    Thanks Rami,

    The MCU side is DDI, but due to route length, I'm running that through another TDP2004 redriver before it hits the TMUXHS4612 demux.

    After the TMUXHS4612  demux, I route one path through another TPD2004 redriver to reduce the parasitics, and then through a TMUXHS4612 mux.

    The other path routes through a (currently unknown) DP to TMDS/HDMI level shifter and then through the other channel of that same mux.

    This way, the same DDI bus can become DP, HDMI, or other TMDS based buses by selecting demux and mux channels.

    I chose TMUXHS4612 over TMUXHS4512 because it allows the 5V0 sideband signals to pass through when HDMI is selected.

  • 0 in reply to Dan Rechichi
    TI__Mastermind 18950 points

    Hi Dan,

    I'm part of the redrivers team, I've pinged a colleague to advise on the suitability of the TDP2004 specifically for this application. I do want to point out for now that the redriver is intended to compensate for insertion loss. If you have long traces in your system, a redriver should help signal quality, and I believe insertion loss is one of the parameters that mux parasitics can contribute to. But there might be other parasitic effects that the redriver does not improve.

    Best,

    Evan Su

  • 0 in reply to Evan Su
    TI__Genius 13986 points

    Hi Dan, 

    TDP2004 can compensate for AC-coupled signal with the speed up to 20Gbps. For DP/HDMI signal, this will work as long as the signal is AC-coupled. 

    Best,
    J