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ADV7513 Differential output appears single ended

Question asked by lopihyilfrtuky4e on Mar 18, 2014
Latest reply on Mar 24, 2014 by GuenterL

Hi,

 

We are using an ADV7513 and have found a monitor dependent problem. It appears that on certain monitors there is a "salt & pepper" effect. that is that white or black pixels appear typically in opposition to the brightness of the background, black in lighter areas and white in darker areas.

 

On a hunch I removed our ESD clamps with no apparent change in performance. I suspected maybe capacitance was an issue. Then I looked at the signals on the ESD parts pads and found that the inverted signal appeared to be proper. that is to say there was a fair swing around the reference. I then looked and the non-inverted signal and found it to be very "weak". there was something there but it looked almost like the differential signal was acting single ended.

 

Are there some registers in the device that need to be set in a particular manner that we may have overlooked from the user guide "Must be set" section? what other issue could cause the salt and pepper that is monitor dependent?

 

A schematic of the circuit is included below if it helps

 

Thanks

D

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