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TDP158: Does TDP158 support the sink side?

Part Number: TDP158
Other Parts Discussed in Thread: TMDS181, TMDS171

Hi Team,

My customer read the TDP158 datasheet and find, in the DDC snoop section, we only have the recommendation on the DDC snoop on source side, but there is nothing on sink side, they are asking if it mean we recommended to use TDP158 on source application. Since they have some projects on TV, so they want to understand, if they can use 158 both on laptop and tv application.

  • Hi,

    The TDP158 can support sink side. But there are few things to consider if using the TDP158 on the sink side.

    1. The sink side input is a DC-coupled HDMI. The TDP158 requires its input to be AC-coupled. You can work around this by having the input AC-coupled and with external termination network. But the external termination creates a double termination which would reduce the input signal amplitude. The source has to compensate for the reduction in signal amplitude.

    2. The TDP158 is a redriver with a fixed RX equalizer. On the sink side you could have different cable with different loss profile. It is impossible for one fixed equalizer to compensate for the different cable loss which could create under or over-equalization conditions. For under-equalization condition, depends on the source TX and sink RX capability, they may able to provide additional compensation. But over-equalization condition can not be compensated.

    So it is better to use the TMDS171 or the TMDS181 retimer for the sink side design. The TMDS171 and TMDS181 provide DC-coupled input, while the adaptive equalizer can adapt automatically for the different cable loss.