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AD9389/AD9889B audio drop outs at high frequency video patterns

Question asked by gelke on Sep 28, 2011
Latest reply on Oct 12, 2011 by gelke

Hello Matt, Dave or coleagues

Thank you for your help so far, but unfortuntaely our problem with audio and the AD9389/9889 is not yet resolved.

 

1.) Audio is appearing and disapperaing in 1 - 2 second intervalls

2.) The problem is dependend on the slope of the parallel video inputs D(23-0), the video pattern, the TV-Monitor and the HDMI cable.

3.)  The problem shows reliable, when the test image is 1080p 24Hz, black and white with a fine grain pattern (all data lines switch very fast between high  and low).

4.) The problem improves, when we reduce the drive strength of data lines D(23-0) from the FPGA to the AD9389B.

 

The AD9389B is supposed to work with 1.8V I/O and  3.3V I/O, we  are using 1.8 V I/O. How is the threshold of the I/O receivers switched between1.8V/3.3V? Is there a register setting for this; I did not find one? DVDD is always specified between 1.71V and 1.89V.

 

We are desperately looking forward to your help, since we are in a situation where we have to ship units to customers very soon.

 

Regards

 

Hans & Andreas

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