This thread has been locked.
If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.
I'm doing an HDMI board design and I've encountered what I think is a very large intra-pair skew requirement. The HDMI spec states 0.15Tbit which at 6GHz is 25ps. As a rule of thumb this would equate to about 3.8mm of FR4 (150um/ps). In TI's doc http://www.ti.com/lit/an/slla414/slla414.pdf section 2.4 (displayport) suggests 5mil (125um) for 20ps. I do not know why 125um is suggested for a 20ps skew when it only needs to be 3mm!
Have I made a glaringly obvious mistake?
I'm not quite sure I understand. Why are you concerned about the DisplayPort intra-pair skew requirements when your design is for HDMI?
We are glad that we were able to resolve this issue, and will now proceed to close this thread.
If you have further questions related to this thread, you may click "Ask a related question" below. The newly created question will be automatically linked to this question.
In reply to I.K. Anyiam:
I referenced the displayport figure of 20ps and 5mils (125um) as this is comparable in speed to HDMI. Your doc doesn't give any figures for skew in terms of ps or mil for HDMI, only in terms of Tbit.
The quoted figure of 0.15*Tbit for HDMI is equivalent to about 25ps.
So I could've rephrased my question and only mentioned displayport, and then asked why do you recommend 5mils for a 20ps skew when this need only be 3mm?
In reply to Graeme Parker:
Understood. Less than 5 mils of intra-pair and interpair skew is our generic, rule-of-thumb recommendation for most high-speed designs across all frequencies (LVDS, DisplayPort, etc.).
It is just a recommendation, and system designers are welcome to stray from it if they have a solid understanding of the requirements for this system.
Thanks. That's our rule of thumb too. I just wondered if there was a reason it was far less than 3mm.
Thanks for your help.
All content and materials on this site are provided "as is". TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with regard to these materials, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. No license, either express or implied, by estoppel or otherwise, is granted by TI. Use of the information on this site may require a license from a third party, or a license from TI.
TI is a global semiconductor design and manufacturing company. Innovate with 100,000+ analog ICs andembedded processors, along with software, tools and the industry’s largest sales/support staff.