AnsweredAssumed Answered

Strange issue in DDC input channel on  AD8192

Question asked by Captcha on Sep 28, 2016
Latest reply on Apr 18, 2017 by jmarshma

Hello

 

I'm using the AD8192 in cascade(3) and it works very well for the video.

But i have to manage some issue with the selected DDC channel. Sometimes the EDID is ok and sometimes there is errors (bad checksum !).

i use a video generator on the input and i force it to read the edid from the tv screen connected on the output of the AD8192

The DDC input of the AD8192 is connected with pull-up(47k) and the VREFAB and VREF_COM is at 5V.

 

I put my scope  on the clock and the data and something is strange in the input of the selected DDC port.

There is a glich of 100ns at each rise front of the clock followed by a level of 2.5V during 200ns and after the level is correct.

 

Any idea of this strange beahavior ?

 

see attached file.

 

thanks

Franck

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