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27MHz clock from ADV7403

Question asked by MKempisty on Sep 4, 2014
Latest reply on Sep 5, 2014 by DaveD

We are using an EVAL-739XFEZ with an ADV7391 evaluation board.  We are configuring the ADV7391 to display NTSC color bars but they do not display in color until we first feed NTSC video into the ADV7403 to "true up" the 27 MHz clock from the ADV7403 tot he ADV7391.  Once this is done the color bar test pattern displays fine.  Our actual test system which will be using these evaluation boards does not have a source of NTSC video.

 

I have tried turning on PLL_DIV_MAN_EN and setting PLL_DIV_RATIO along with VCO_RANGE_MAN and VCO_RANGE but cannot get the LLC to move from about 7 MHz.  Am I missing something here?

 

I have configured the ADV7403 PRIM_Mode to 1 and VID_STD to 6 to get a 27 MHz clock but it appears slightly slow as compared to the clock created after feeding in NTSC video (0.01 - 0.02 MHz slow).  This clock allows our monitor to display the color bar pattern but there is some color "crawl" in a couple of bars.  We are hoping that by improving the accuracy of the 27 MHz clock we will be able to eliminate the color crawl.

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