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TDP158: Use TDP158 to HDMI redriver on DP/HDMI dual mode display source.

Sujin Nam
Prodigy 170 points
Part Number: TDP158
Other Parts Discussed in Thread: TPD8S009, TPD4E02B04

Hi

I want to use TDP158 as HDMI redriver.

On the pins i want to use, DP and HDMI share the same set of interface pins.

And according to product design guide, it requires series AC capacitors and pull-down to HDMI compliant (please refer to Figure1)

<Figure1>

So I placed TDP158 next to pull down and series resistor(for HDMI2.0) to make it HDMI compliant. (like Figure2)

But i'm not sure it's OK.

TDP158 datasheet says it is level shifter redriver ac-coupled HDMI signal to TMDS.

If this is the case like Jetson TX2, pull-down and resistor not required.

TDP158 datasheet(Figure3) shows that it uses series capacitor on source side, but i'm not sure i can use pull-down and series resistor.

<Figure2>

<Figure3>

<Question>

1. Should i use pull-down and series resistor on the source side of TDP158 or just capacitor?

2. Can i directly connect the sink side of TDP158 to HDMI connector without any EMI/ESD elements?

Thanks.

Sujin.

  • 0
    TI__Expert 5455 points
    Hello Nam

    As you can see in the part of Features, this device works with AC-coupled TMDS or DP++ (it means that this device can handle AC-coupled TMDS and DP) to HDMI 2.0. Then, if you have from you GPU (Jetson) a DC-coupled TMDS signal, then you'll need the AC-Caps (as the figure that you put in your post from our datasheet) and with this one, you will have AC-coupled TMDS.
    1.- Therefore, the answer to your first question is the pull-down are not necessary for our device, nor series resistors.
    2.- You can connect directly to the sink ( you can check the ESD parameters on our Datasheet), for EMI, to help to reduce overall EMI in a system the VCC and VDD decoupling caps need to be as close to the pins as possible. Another thing that you can consider is using at a minimum a four-layer stack up to accomplish a low-EMI PCB design.
    On the other hand, if you want to have an extra protection, you can use our TPD8S009 www.ti.com/.../technicaldocuments that is an ESD protection for DisplayPort and HDMI and common mode chokes for protection of EMI.

    Let me know if you have any questions.

    Regards
    Francisco
  • 0 in reply to Francisco Javier Zamudio
    TI__Expert 5455 points
    Hello Nam

    As a comment, for HDMI 2.0 the TVS diodes recommended solution is the TPD4E02B04.

    Regards
    Francisco