Hi, Everyone. I am debugging an image capture board. In this board, th ADV7181B is used to digitalize one channel analog TV signal and the analo video signal is AC-coupled to ADV7181B input pin AIN6, while other analo input pins (AIN1-AIN5) float. The digital image is then sent to FPGA. powered on the board without configuring ADV7181B, so the ADV7181B shoul run by the default register values. But I find that ADV7181B failed t clamp the AC-coupled video input signal to a DC level, so the input signa is a pure AC signal. I have checked all the peripheral circuits o ADV7181B. I do not find any problem. The LLC pin output is right and th REFOUT is 1.71v ...,which looks good. By the way the ADV7181B is a littl bit over-heated.
Anyone ever met the same problem or have any advice?
Thank you!
Leon