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Need clarification on intra-pair and inter-pair skew for TMDS signals (HDMI or DVI) at source connector. Per HDMI spec, @ 225MHz, intra-pair skew is 66ps and inter-pair skew spec is 888ps at source connector. I also found that @165Mhz, intra-pair skew spec is < 90ps and inter-pair skew spec.
What is the max intra-pair and inter-pair skew allowed for TMDS differential traces from TI devices like AM3894, TFP410, DS16EV5110A etc ? The max frequency is 165MHz. Considering about 130-150ps propagation delay for every 1 inch and using the above number, intra-pair skew can be < 600mils and inter-pair skew can be < 8". Even if we consider the soure IC skew, ESD parasitics skew and connector skew, there is still a lot of margin. What is TI's recommendation ? In general I have seen 1" inter-pair skew spec and 5mils intra-pair skew spec which is much lower than what the spec mentions. Am I missing anything ? Please clarify.
I can tell about the TFP410 tha the intra-pair length mismatch is recommended to be less than 5mils, inter-pair length mismatch is less of a concern but the recommendation is to keep the traces <2" and keep the clock slightly longer than the data traces.
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In reply to Elias Villegas M.:
Thanks for that feedback. Is there any documentation that provides these specs and explains them ? The HDMI design guide does not provide the info you mentioned.
In reply to Lakshmi Santosh:
Two resources that have more info, and guidelines are:
Channel Link I design Guide: http://www.ti.com/lit/ml/snla167/snla167.pdf
LVDS Owners Manual: http://www.ti.com/lit/ml/snla187/snla187.pdf
In reply to Mark Sauerwald88474:
Thanks for the documents. But they don't seem to have enough info to answer the questions.
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