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ADV7441ABSTZ-170: improper output, device fault ?

Question asked by NanjundaM on Oct 25, 2017
Latest reply on Oct 28, 2017 by NanjundaM

Hi,

 

We are using the device ADV7441ABSTZ-170 with the Arria V FPGA for VGA & HDMI video input from the PC to process and output with ADV7511WBSWZ. This is our one of the old designs and we are now handling the production of the same board.

 

The VGA input from the ADV7441ABSTZ-170 is properly output through the ADV7511WBSWZ on monitor @1280x1024 resolution.

But when I input ADV7441ABSTZ-170 with HDMI input, I'm not able to get any output on the monitor.

 

From the FPGA, we have enabled a layer of rainbow colors to output to the ADV7511W, when the input is not available to FPGA so we are able to see this on the monitor, but there is flickering in the display.

 

When I checked the impedance (in the off condition) of the HDMI pins at the IC pins, I found that the RXA_2P & RXA_2N pins have the impedance different than the other pins w.r.t. the ground on the board. (other pins are 7M ohm and the two pins are showing 6M)

 

Also when we touched the CRO probe (even without the ground connection to probe) to the RXA_2P signal, the output was visible with some noise.

We also observed that the output was visible to some extent with noise, when we tried to display some plain background on the input (from PC with paint with single color fullscreen mode).

 

So we are suspecting the ADV7441ABSTZ-170 due to its lower impedance on the 2 pins.

 

Can you please help us to understand whether we are going on the right path.

Whether the suspected is correct?

 

 

Thanks & Regards,

Nanjunda M

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