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TFP401: DVI to LVDS, Bad colors on output video-1

lei ju
Prodigy 20 points
Part Number: TFP401

Hi , we are using the two-chip solution of TFP401 and SN75LVDS83B to convert DVI input to LVDS output. we also get color issue as "DVI to LVDS, Bad colors on output video". We have done follow test.

1 We found true green can't be displayed,there are black if we input true green .All the TFP401 green output is low level.

2 If we exchange DVI input wire, DVI-TMDS0,& TMDS1, if we input true red, then LCD display true green, 

3  We use display test software, the display gradient can't work right,Perhaps some color has problem.

4  We change EDID to change display frequency, there are no influence.

5  Our design follows SLLA325A,（HDMI/DVI to LVDS Bridge）.

6 We will try to display all the color to check every RGB output 

Can you give us some advice? Does the EDID will influence the result?

   

  • 0
    TI__Mastermind 18655 points
    Hello,

    Could you please share your schematics? What are the results of checking every RGB output from the TFP401?

    Regards,
    Joel
  • 0 in reply to Joel Jimenez0
    Prodigy 20 points
    I have found the reason, the root cause is the LCD have 8 bit or 6 bit LVDS, the reference is for 8 bit LVDS. So if we use in 6 bit LVDS mode. The bit7 and bit6 will miss. Then the color is bad.
    Solution 1 , change LCD mode to 8 bit LVDS,
    Solution 2, change the schematic,connect QE7-B7 to 83B D22 in 6bit LVDS mode,all other data should be changed in 6bit LVDS.
    Thanks!