ADV7202: Operation of clamping function

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Q 
 1) How does the device decide what level (digital value) to set the blank value to initially? 2) At the moment I am reading the digital value corresponding to blank out of the device, then I am programming the clamp register with the value derived from this to make the gain equation correct. I am also providing a sync pulse during blank to activate the clamp at the right point. Is this procedure correct? 
 
 A 
 1. We expect the ASIC to monitor the output digital code and determine from it where the actual blank and sync levels are. The user will then control the clamps to 'steer' the blank level to a specific code. Note the programmable blank level within the decoder is only a level which will not be affected by gain or AGC. I would expect that the programmed value here will equate to the output blank level that the customer has chosen. 2. Your method of control seems correct to me. It is important that it is AC coupled to the part. Our evaluation board used a DC voltage clamp at its input as we did not dynamically control the clamps. This should be removed.

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ADV7202: FAQ