HDMI schematics reviewing (ADV7611, ADV7612, and other)

Few things often forgotten during reviews of ADV7611, ADV7612., ADV7619 and other schematics;

First - It is suggested to follow recommendation from Design Support Files pages:

Here are common mistakes:

1. Pullups on DDC lines - should be: 47k +/- 10% (please refer to table 4-37 of HDMI Specification),

and should be only on SCL lines:

2. Make sure there is a shunt 390k resistor in parallel to XTAL (for 7611 and 7612; on 7619 there is no

need for resistor)

3. Make sure DET line on HDMI is connected properly (refer to HDMI spec.). If one is not connected -

HDMI source will not detect sink and may not send any video to the

A 1k +/-20% resistor should be connected between DDC+5V and Hot plug detect.

Refer to section 4.2.9, table 4-38 in HDMI Spec.

4. Make sure an ESD protection used on HDMI TMDS lines doesnt affect the characteristic impedance

of lines to be outside spec'd in HDMI recommendation. Otherwise design is not compliant and

will cause problems especially at higher frequencies. It is suggested to use ESD protections

same as in the schematics.

Rgds,

vito

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