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Using SN75LVDS83B with NEC NL10276BC20-04

Bogdan Orasanu
Intellectual 270 points

Other Parts Discussed in Thread: SN75LVDS83B

Hello all,

 

First let me thank Ross for his help, up to this point!

 

Now, let me explain my problem. Please forgive the lenght of this post.

The project is to convert and replace some CNC machinery displays to 1024x768 resolution (from 800x600).

The original design is using TTL interface (41pin Hirose) to a NEC NL8060BC26-11 or 17 panel (TTL, 800x600, 18bit). The replacement panel has to be NEC NL10276BC20-04 (1024x768, LVDS, 18bit, based on THC63LVDF64B receiver) as per customer request.

For the TTL -> LVDS translation I am planning to use a SN75LVDS83B, as opposed to the datasheet recommended THC63LVDM63A. As the customer's machines cannot be touched for testing purposes, I setup a similar environment, with a difference (it turns out to be a crucial difference!!) : in lack of the NL10276BC20-04, I used an AUO_G104SN02_V0 (800x600, LVDS, 18bit) that I had readily available.

All worked just fine, without a hitch. At this point I jumped ahead of myself, and without researching better the NL10276BC20-04, went and did the final test at the customer site. Embarasingly (doh!) it did not work, with only white display.

After returning to the lab, and reading some more, I have to admit that I am lost. The new panel does not use the HSync/VSync signals at all. It needs that the DE (or ENABLE depending of terminology) be synchronised with the H/VSync. 

Attached are the DS for the all three types of panels involved. 

1031.AUO_G104SN02_V0.pdf

7838.NEC_NL8060BC26-17_SVGALCD.pdf

8637.NEC_NL10276BC20-04_11ed.pdf

Is there a different way to connect the panel that I did not see? Any suggestions?

 

Thank you in advance,

Bogdan

  • 0
    TI__Guru* 76130 points

    Hello,

    we are reviewing the information and we'll reply soon.

    Regards.

  • 0 in reply to Elias Villegas M.
    Intellectual 270 points

    Hi Elias,

     

    Just a little follow up: Upon probing the HSync, VSync and DE, with a scope, noticed that the DE is corresponding to the requirement. As a further test, I connected the AUO panel (LDVS) again, but connected the HSync & VSync as per the requirements of the NL10276 panel (D24=HSync=High, D25=VSync=High/Low, as the AUO panel is capable of using the "DE mode"). It did work fine. I started to suspect the NL10276 panel as being defective. This will save me some face....:-)

    Thank you for looking into this!

    Best regards,

    Bogdan

  • 0 in reply to Bogdan Orasanu
    TI__Mastermind 36085 points

    Hello Bodgan,

          I started by a comparison between both transmitters, looking for some significant difference between them which could ends in a issue, but I found nothing.

          After the comparison and taking into account your last update, I tried to find such an incompatibility between the SN75LVDS83B and the NL10276BC20-04 but everything looks good since the datasheet point of view. This makes sense to your assumption of the defective panel.

    Try to probe with another NL10276BC20-04 and let me know if there is an update on the issue.

    Best Regards,
    Diego.

  • 0 in reply to Diego Cortes
    TI__Mastermind 36085 points

    Hello Bodgan,

    Also be so kind to take a look on this application note http://www.ti.com/lit/an/slla300/slla300.pdf  and confirm that You are using a proper configuration for the inputs on the SN75LVDS83B, and check if You are updating the CLK signal when You change from the AUO_G104SN02_V0 to the NL10276BC20-04.

    Regards,

    Diego.