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Urgent: ADV7611 HDMI disconnection (HPD de-asserts momentarily) due to EM Noise coupling on TMDS lines during ESD testing

Question asked by padmanathanj on Oct 30, 2015
Latest reply on Mar 28, 2016 by GuenterL

Hi,

 

           In our design (Display Unit) using HDMI Receiver ADV7611, when ESD is applied to front panel ports (HDMI, USB), the HDMI disconnection occurs momentarily (HPD de-assertion momentarily) due to which the Video player in the Source device gets paused, which is an issue.

 

In debugging, it is found that the CM Noise coupling to TMDS lines (/overall GND bounce) when ESD pulse is applied, is the reason for the issue.

 

Is there any settings to de-bounce (delay) the detection of Momentary Data/Clock loss in TMDS lines, to avoid momentary HPD de-assertion (or Reset of HDMI Section).

 

Or, is there any implementation to improve the Noise Immunity of TMDS Inputs in ADV7611.

In our design, the TMDS channel is;

     - HDMI connector board (very short trace between HDMI Type-A Connector to FPC connector) --> FPC (short length in Flex PCB < 2 inch trace) -->  CPU Board (1 inch trace between FPC connector and HDMI Receiver with ESD Diodes and Common Mode Choke);

     - and all TMDS lines meets the Impedance requirements (as per the HDMI CTS 1.4b).

 

Note: The supported HDMI Resolution in the system for the HDMI Receiver is 720p/1080i (Max clock: 74.25MHz).

 

Currently the issue occurs even at lower ESD levels (+/-4KV) itself.

 

Thanks & Regards,

Nathan JP

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