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ADV7180 and ADV7393

Question asked by sin on Jan 5, 2015
Latest reply on Jan 19, 2015 by sin

Hi

I have some questions which my customer asked me about ADV7180 and ADV7393.

 

Q1)
Please find attached file about the test setting.
When color bar test signal is inputed in ADV7180, we can find hatch patterns at the out of ADV7393.
Then it seems that those hatch patterns of RGB are oscillated and that value is about +/-5 degree
from the center, under subcarrier frequency not locking.
The CLK signal at the out of ADV7180 may include some jitters and cause the oscillation of the hatch patterns.

 

In addition, followings are found.
1. As the 27MHz signal by signal generator is inputed in ADV7393 directly as CLK, this oscillaion
   cannot be found.
2. As the 28.6363MHz signal by signal generator is inputed in ADV7180 directly as CLK, this oscillaion
   cannot be found.

 

Do you have any solution or information of the oscillation ?

 


Q2)
When the input level of ADV7180 is suddenly changed, it is found that the clamp is not operation.
My customer has try to change the resistor to other value, but the clamp remains no-operation.

Do you have any solution or information of this matter ?


Q3)
In "SD SUBCARRIER FREQUENCY CONTROL" of ADSV7393 datasheet, it is hard to understand the equation
that the value of the registers is calculated using.
How to calculate "Number of subcarrier periods in one video line" ?
How to calculate "Number of 27 MHz clock cycles in one video line" ?

Sorry, I don't know the detail of the calculation.
Please let me know these processes of calculation.


Best Regards,

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