There are several issues with the TMDS181 that I need to discuss.
1. First, the TMDS differential outputs (OUT_D2n/p, OUT_D1n/p,...) seems to be severely band limited when driving a full 6GB/s per lane in Retimer Mode. Specifically, we are observing 3db (power, 50% vertical eye closer) ISI when we are running at 6GBps on any of the data lanes. We are observing this vertical eye closure on the output of your Evaluation Board (TMDS181RGZ Evaluation Module).
Is this behavior expected? If not, have you observed it before and/or what can we do to prevent it? If it is not expected and you have not observed this before, then what are the next steps we can take to resolve this issue?
2. Is there any way to get a post equalization view of the eye diagram (going in to the retimer/redriver) at full 6Gbps mode. The user guide for the Evaluation Board says there is a bug (in the eye scan tool) that currently makes this impossible. We are having problems with intermittent errors using the TMDS181 at 6G per lane. Thus, an eye diagram at the retimer input (post equalization) would be very useful. Is there some way to work around this bug. If you don't have time to update your eye scan tool with the required fixes, we would be willing to make the changes ourself or create our own version of the tool. We just need to know what to do differently
3. We currently have a very old (pre-release) version of the eye-scan tool (0.0.0.12). Your documentation seems to indicate that there is a newer version of the Eye Scan tool available (Version 1.05). We need access to the most recent version (v1.05??) of the eye scan tool ASAP.
Finally, we want to use the TMDS181 to solve some very specfic problems we are having with a current product. The anticipated volume is at least 20K pieces per year (and may be significantly higher). However, we are experiencing problems eye collapse on the output and unexplained bit errors. We already know that there are a variety of undocumented registers available in the chip that give the eye scan tool access to status and control that is not documented in the part's data sheet.
It would be very helpful to our debug efforts if we had a detailed understanding of what these registers do. We are aware of the purpose and limitations of undocumented registers. We will sign an NDA and we will not build any features into our product that actually use the undocumented registers without your permission. We simply want to use these registers to debug our problems with your TMDS181 so that we can get you part in to our production line and we both can make a little money.
Thanks,
Ken
