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(ADV7390)Is there any possibility to change the sync depth with CVBS output.

Question asked by donadona999s on Feb 8, 2016
Latest reply on Apr 21, 2016 by donadona999s

Hi !

 

Is there any possibility to change the sync depth with CVBS output with not changing the output gain?

Our customer are using ADV7390 as DIGITAL to CVBS.

And they said the output signal level is something wrong.

ADV7390.jpg

They input the color bar input signal by digital but the 100% white has only 704mV( I think 1V is correct),

and sync depth has only 212mV(I think 286mV is correct).

Their script is this.

===================

0x17 0x02

0x00 0x10

0x01 0x00

0x80 0x10

0x82 0xC3

0x8C 0x1F

0x8D 0x7C

0x8E 0xF0

0x8F 0x21

0xE0 0xFE

0xE1 0x45

0xE2 0x85

0xE3 0x54

0xE4 0xEB

0xE5 0xB6

0xE6 0x91

0xE7 0xF8

0xE8 0x07

0xE9 0x00

0xEA 0xC0

0xEB 0xC3

0xEC 0x03

0xED 0x58

0xEE 0x85

0xEF 0xCA

0xF0 0xFF

0xF1 0x00

0x88 0x00

0x8A 0x0C

===================

And I tried this with ADV7180-ADV7391 EVAL board but nothing wrong.

=> We are inputting the color bar with CVBS so the white is not 100%white but sync depth is almost 286mV.

ADV7390.jpg

So I think some thing is wrong with the connection to ADV7390 output.

=> We know that our customer connect 75Ohms to GND but don't know what is connect from there on.

 

I think if they use ADV7390 with "DACoutputLevel = default" , this shouldn't happen.

I mean in any case , ADV7390 will output the DAC signal with 286mV sync depth.

Is my understanding is correct?

Or can this happen by the input signal or something?

 

Also if you can give me some advice why the sync depth is small ( it look like the output gain is 75%) ,

it would help us and our customer.

 

Best regards.

Kawa

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