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TDP158: Source Termination set automatically based off TMDS clock ratio status

Luke Duzanica7
Prodigy 110 points
Part Number: TDP158

Working on getting a initial settings for all our registers for my company and saw that the TMDS clock ratio field was updated from DDC snoop on I2C that occurs on the source side of the interface. We haven't sent out the circuit board for fabrication yet but have the design referenced towards the application example shown in Figure 46 where the source side is always grounded. If we use the figure as a reference then it seems that the automatic termination would always have to be changed when we switch the rate from HDMI 1.4 to HDMI 2.0 or is the text in the register map incorrect and will see the DDC snoop on the sink side also to change the termination?

  • 0
    TI__Guru*** 140055 points
    Luke

    DDC_SNOOP is on the SDA_SNK and SCL_SNK side. So the snoop configuration can be implemented where the SDA/SCL from the source is connected directly to the SDA/SCL pins of the sink. The TDP158 needs the SDA_SNK and SCL_SNK pins connected to the sink DDC pins so that the TMDS_CLOCK_RATIO_STATUS and TERM bit can be automatically set otherwise it will have to be set through I2C.

    Thanks
    David