DS90UH948-Q1: Using CML output to verify the FPD-link healthy and what is the acceptable eye diagram for CML out

Hi Roy,

1. The register setting is correct.

2. You only need to supply the target PCLK frequency. 947 will generate data at the target frequency once you supply the PCLK.

3.1. Yes.  3.2, the 360mV is peak to peak. 

Best Regards,

Charley Cai

Hi Charley,

Thank you for your comment.

 Based on your comments, I still have some questions showing as below

1. no question.

2. Does CML out is only test data from 947? I mean that if I connect to real LVDS signal into 947 and then CML output is the real data that I send from 947?

3.1 no question.

3.2 If the 360mV is the peak to peak which means +/-180mV, my test result seem to weird. You could see the peak value is over 200mV, and the EH spec(+/-150mV) is difficult to achieve.

Could you give me some comments for this result?

attach the measurement

Regards,

Roy

Hi Roy,

2. The FPD-Link channel will always be running regardless of actual data is sent or not. If no data is sent, we will just stuff dummy data into the channel. The CMLOUT will just output the dummy data. If actual data is sent, CMLOUT will just be the actual data. Note that they will be encoded so you really cannot tell the difference. The CMLOUT will be applicable for both cases.

3.2 The 360mV is just a typical value. Your eye diagram looks fine. 

Are you using a differential probe?

Best Regards,

Charley Cai 

Hi Charley,

2.    Got it. Thank you for your comments.

3.2  Do you mean EH is the approximate value and couldn't need in interval [-180mV/180mV]? Does EH have maximum value and minimum value? And Does EW need to follow > 0.4UI?

Are you using a differential probe? Yes

Regards,

Roy