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VGA Video Generation: ADV7123 vs ADV7391 for 1024x768@60Hz XGA video

Question asked by gdownes on Aug 18, 2011
Latest reply on Aug 19, 2011 by vito



I currently am using the ADV7123 to generate XGA video 1024x768@60Hz which current requires 34 I/O lines (including 3x 10bit datalines, blank and sync).  If I want to accomodate a downgrade path for an FPGA who is sourcing a video I will loose the required I/Os.


Since I already have x2 ADV7391s on the board for something else, I am curious if I can use a third device to generate VGA video with separate syncs.

From the looks of it, yes it can, where the syncs pins on the device are now outputs.  The format however is the question.  Can the ADV7391 be used to generate VGA video at 1024x768@60Hz.  If not, is there something that can do so that requires less pins than the ADV7123.


The ADV7123 is a straight forward DAC where we can generate the embedded sync on green if required.  External syncs we can route separate HSYNC/VSYNC lines out from the FPGA.  I hope the ADV7391 can be used in the same way when operating in nonstandard video mode as outlined on page 49 of the datasheet.


Message was edited by: gdownes