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ADV7391 / câble detection not working

Question asked by J-François on Aug 6, 2018
Latest reply on Aug 10, 2018 by J-François

Hi,

We use an ADV7391, connected to the screen through one ADA4431 filter.

In order to detect a failure on the internal load resistor, we want to use the câble detection feature of the ADV.

RSET si set to 510ohms and the internal load is set to 37,5ohms.

The configuration of the ADV is the default one updated with the values of the Table 82 (8-Bit 625i YCrCb In (EAV/SAV), CVBS/Y-C Out) :

 

The electrical diagram is above :

 

We expect that if the resistor connected to DAC1 is broken, the "DAC1 cable detect" bit into register 0x10 is updated to value "1", but this bit is never set !

The result is the same if the register 0x00 is set to 0x10 (to disable DAC2 which is connected to ground).

 

Is there something wrong into the diagram, or in the interpretation of the datasheet ?
Someone has an idea ?

 

Thanks for all

Jean-François

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