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ADV7125 timing inquiry

Question asked by JerryS on Sep 15, 2015
Latest reply on Sep 16, 2015 by GuenterL

Hello,

 

I used ADV7125 in project with core chipset Rockchip RK3188.

When ADV7125-240 output to monitor with 720P or 1080P after checked EDID of monitor, it has some kind noise and flashing that is much apparent in dot white/black horizontal line as phase shift issue.

a. I measured the analog RGB output, Hsync, Vsync, data clock, DE pins of ADV7125. These pins' signals and frequency are fine.

b. I try to enable auto phase function of monitor that issue has some improvement, but not fixed. Then I manual adjust phase shift of monitor that it can fix it.

c. I try to use NB and some of STB VGA output to same monitor and video resolution, the monitor display video quality ok with auto phase function enable.

d. per double checked schematic and power noise of ADV7125, they are fine.

e. I found a Hsync strength waveform when VGA cable connected as below picture.

    I am not sure this Hsync is key point or not.

f. I attached ADV7125 schematic for your reference.

 

My question is why my ADV7125 output video can't be display good video without phase issue? it still can't be fixed even I enable  "auto phase adjustment function" of monitor.

or you can give me some of recommendation which checked point I missing.

Thank you.

 

 

720P, Analog B channel waveform.

   720P_Analog B Out_2015-09-15_0_144709.jpg

 

Pixel clock with Hsync, NO VGA Cable connected.

no vga cable.jpg

 

Pixel clock with Hsync,  VGA Cable connected.

1.jpg


Pixel clock with Hsync,  VGA Cable connected, Zoom In

2.jpg

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