AnsweredAssumed Answered

AD9889B HDMI output is not good for particular monitor and cable

Question asked by usaghi on Sep 10, 2012
Latest reply on Sep 11, 2012 by GuenterL



Our customer is facing problem, when output from AD9889B, particular pair of monitors and cables do not display normally. Means the monitor repeats on and off, or go into sleep mode by recognizing it doesn't receive normal HDMI signal.

This HDMI source set is determined OK on TMDS eye-pattern characteristic under HDMI testing.

The customer tried other HDMI source devices, Panasonic and other inexpensive network media player for these monitors and cables, they showed normal output.

The customer also tried to operate DriveStrength registers of AD9889B, at the address of 0xA2 and 0xA3. After saveral trial and error, they could find the value 0xFF for both registers could resolve the issue, display normal pictures on the monitor.


The customer knows programming guides recommends 0x87 or 0x84, depends on pixel clock, however because there is no futher explanation what these hex values really mean on the device, the customer is not able to judge what is good for these registers and how to do.

If it is possible, could you please explain more in detail of the DriveStrength registers, meaning of each bit, or please give your any comments and advice ?

If you feel there may have something wrong on schematic or PCB, I will try to get.


Best Regards,