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AD9389/AD9889B audio drop outs at high frequency video patterns

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.


Hans & Andreas

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