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How are scaling and resolution handled with the TFP401?

Jamaal_Charles
Genius 3245 points
Other Parts Discussed in Thread: SN65LVDS93A, TFP401A-EP, TFP401A, TFP401

Hi,

We are hoping to convert HDMI to LVDS using the SN65LVDS93A coulped to the TFP401A-EP.  What I can't figure out is how it knows the resolutions or scale of the display?  I assume that is handled in software, but I'm not sure how to set it up. 

Sorry for my ignorance of how this part works.  Thanks for any help you can provide.

Jamaal

  • 0
    TI__Guru* 76130 points

    Hello,

    Some displays support different resolutions and will lock to the appropriate, but to be sure you need to look at the datasheet of your display and set your system to a clock frequency that will be supported by your display, when I say "set your system" I am referring to the clock frequency and bit mapping of the LVDS93A and TFP401A in order to match the display's requirements.

    Regards.

  • 0
    TI__Mastermind 20985 points

    Jamaal, these two devices are a deserializer and serializer that operate across a pixel clock frequency range.  The higher the display resolution is, the higher the pixel clock frequency is.  The two devices will automatically operate when the frequency range is within their spec.

    Best regards,
    RE

  • 0 in reply to RE
    Genius 3245 points

    Thanks for your help,

    A couple more questions, sorry.  First, is than eval board for these parts?  Or maybe something that uses them with an HDMI input and LVDS output? 

    The other issue is that I'm using Windows on an embedded computer board, and just have an HDMI output.  I'm not sure how I'm going to be able to manipulate the Windows HDMI driver to make any changes to the clock speed.  So, my hope is that it does make these changes automatically, but I really would have to test this out.

    Thanks again!

  • 0 in reply to Jamaal_Charles
    TI__Guru* 76130 points

    Hello,

    We don't have EVMs for a LVDS93 and a TFP401.

    As Ross already said, the LVDS93 and TFP01 work within a pixel clock range, if your HDMI output is within these frequency ranges then both devices should sync with no issues, if the HDMI output is outside the freq range, then the output of the TFP401 will not generate the expected image. You can approximate what clock frequency is your output if you know the resolution and the frame rate, for example a 1200x900@60Hz will give you an approximate clock freq of  (1200)*(900)*(60)= 64.8MHz

    Can you tell what production volumes are planning?

    Regards. 

  • 0 in reply to Elias Villegas M.
    TI__Genius 14317 points

    Hi Jamaal,

    To add to what Elias said:

    The devices you chose allows single channel DVI/HDMI to single channel LVDS which means that display panel max resolutions are limited to 1400 x 1050 and perhaps 1280 x 1024 (SXGA). Common allowed DVI/HDMI input resolutions for your two device configuration are VGA (640 x 480), SVGA (800 x 600), XGA (1024 x 768) and SXGA (1280 x 1024).

    See http://www.epanorama.net/faq/vga2rgb/calc.html to calculate clock rates for these and other resolutions.