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TMDS181: the input is AC coupled

Yuta Nishie
Genius 3240 points
Part Number: TMDS181
Other Parts Discussed in Thread: SN65DP159, TDP1204, TMDS1204

Hi,

1. Customer wants to use TMDS181 as input side (source). The TMDS181 receives AC-coupled signals, but could you please tell me a reference circuit or precautions for this?

　The customer input signal conditions are as shown in the attached Excel file.

crosspoint_sw_electrical_characteristics - コピー.xlsx

2. Figure 1 of the application Report shows an example circuit for AC coupling. Can this circuit be used under the customer's input signal conditions? In the thread below, SN65DP159 was recommended, so I would like to know if TMDS181 can be used.

Application Report：https://www.ti.com/lit/an/slaa893/slaa893.pdf

E2E：https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1209228/tmds181-hdmi-4k-video-in-source-mode-setup/4570163

Best Regards,

Nishie

  • +1
    TI__Genius 13290 points

    Hello, Nishie,

    1. The TMDS181 input supports only DC-coupled signals.

    2. The TMDS181 output can be AC coupled, but requires an external termination network, as in Figure 1. TMDS181 output amplitude needs to be increased to compensate for the double termination.

    You need to use DP159 for your application which supports AC-coupled input.

    Thanks,

    Zach

  • 0 in reply to Zach Dryer
    Genius 3240 points

    Hi Zach-san,

    Thank you for your support.

    Let me ask you an additional question.

    Does the DP159(SN65DP159) support DC-coupled signal input? If not, could you introduce a Retimer that supports HDMI2.0 (6Gbps/lane) and AC/DC-coupled input?

    Best Regards,

    Nishie

  • +1 in reply to Yuta Nishie
    TI__Genius 13290 points

    Hello,

    Dp159 supports AC coupled input. 

    You can consider TDP1204 for source side applications which accepts AD or DC inputs and outputs or TMDS1204 for sink side applications.

    Both support AC or DC inputs for up to HDMI 2.1. However, these are redrivers. 

    What is the application here and why are retimers necessary?

    Thanks,

    Zach

  • 0 in reply to Zach Dryer
    Genius 3240 points

    Hi Zach-san,

    Thank you for introducing the product.

    I thought a retimer with a CDR would be better because the input signal quality is not good. I will see if the redriver can handle it.

    Best Regards,

    Nishie

  • +1 in reply to Yuta Nishie
    TI__Genius 13290 points

    Nishie,

    Excellent. Please start a new thread when you have other questions about either HDMI 2.1 redriver and need assistance.

    Thanks,

    Zach