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TFP403 does not work with new USB-DVI adaptor

Jonathan He75792
Prodigy 30 points
Other Parts Discussed in Thread: TFP403

Hi, We have been using TFP403 and USB-DVI adaptor for a few years and it works fine until recently we bought the newer USB-DVI adaptor. We just bought Gefen EXT-USB-2-DVIHD and it does not work with TFP403, SCDT is low and no video output. The older version EXT-USB-2-DVI works fine with TFP403. It is now replaced with the newer one EXT-USB-2-DVIHD so we have to buy the newer one. I know all USB-DVI adaptor use Displaylink chips so they may use different chips. The newer adaptor may use newer chips.

My question is, since TFP403 and USB-DVI adaptor both meet DVI specification, why some of them can work together sucessfully but others cannot? Is it possible that TFP403 does not meet the newer DVI specification (if there is any)? Is there a way to work around the TFP403 circuit on PCB to make it work with newer USB-DVI adaptor?

Thank you.

  • 0
    TI__Guru* 76130 points

    Hello Jonathan,

    Is it possible for you to tell us what IC uses your Gefen adapter to transmit the DVI signals?

    The TFP403 is only single-link capable, so, if your USB-to-DVI converter uses always a dual link there will be a problem.

    Regards.

  • 0
    TI__Mastermind 20985 points

    Hi Jonathan, are you seeing the problem occur with multiple TFP403 devices, and multiple EXT-USB-2-DVIHD devices?  Does the EXT-USB-2-DVIHD work with other DVI receivers than the TFP403?

    Thanks,
    RE

  • 0 in reply to Elias Villegas M.
    Prodigy 90 points

    Hi, Elias,

    I am not able to give you the part number of transmitter IC. I opened the box and it was covered with a shield. I don't want to desolder it because I want to exchange it if they have old ones.

    If dual link is the problem, what would you suggest to fix this problem? Thanks.

  • 0 in reply to RE
    Prodigy 90 points

    Hi, RE,

    Yes. I tried different boards with TFP403 and different EXT-USB-2-DVIHD. The result is the same. I also tried with other brand (Arkview) USB-DVI adaptor that has a newer chip. And it does not work with TFP403 either.

    I do not have other DVI receiver. We tried EXT-USB-2-DVIHD with monitors and it works fine. But I do not have other DVI receiver chip. Do you know if there is any other DVI receiver IC? Does Analog Devices have any?

     

    Thanks.

     

     

  • 0 in reply to Jonathan He15351
    Prodigy 90 points

    Hi,

    The Displaylink (the IC provider) Tech support says their newer chip ' has the DVI
    TX built into the chip'. That is the different with older chip. TFP403 works with older chip but does not work with newer chip. So this DVI TX should be the reason. Do you know what is DVI TX? Does this make sense?

     

    Thanks.

  • 0 in reply to Elias Villegas M.
    Prodigy 90 points

    Hi, Elias,

    I find the old Gefen USB-to-DVI converter use Displaylink DL-160 chip, which works fine with TFP403.

    The product brief for DL-160 is here. (http://www.displaylink.com/pdf/DisplayLink%20DL-120%20and%20DL-160.pdf)

    The newer Gefen USB-to-DVI HD converter probably use Displaylink DL-195 chip, which does not work with TFP403.

    The product brief for DL-195 is here. (http://www.displaylink.com/pdf/dl_pb_125_165_195.pdf)
    Any idea about why DL-195 does not work with TFP403? Any solutions?  Thanks.
  • 0 in reply to Jonathan He15351
    Prodigy 90 points

    Hi,

    Displaylink tech support has confirmed that Displaylink chip only use single link. So this is not a problem. He thinks that 'There
    must be some timing difference between the DisplayLink DVI and the TFP403. Displaylink chip has passed DVI
    compliance so it meets the spec.'  So now the problem is, both TFP403 and Displaylink pass DVI compliance, why not they can work together? 

  • 0 in reply to Jonathan He15351
    TI__Mastermind 20985 points

    Hi Jonathan, can you tell us if there's any dependency on the resolution or cable length?  Lower resolutions involve lower frequencies.

    Thanks,
    RE

  • 0 in reply to RE
    Prodigy 90 points

    Hi, RE,

    No dependency on resolution. The USB-DVI adapator has the display manager installed on your PC that lets you change resolution from 640x480, 800x600, ,,, until 1680x1050 or more. With the old Displaylink chip, it works with TFP403 no matter what resolution you set up. You will see SCDT is high and video is coming out. Of course the pixel clock frequency is different when changing the resolution. But it always works no matter what resolution is. When TFP403 never works with newer Displaylink chip, no matter what resolution you set up. 

    It is not dependent with cable length. The cable length is not long (1.5meter) and I always use the shorter cable and it works with older Displaylink chip and TFP403. Actually I tried longer length of cable and it works with older chip. But with newer Displaylink chip, TFP403 does not work, no matter what length or brand of cable.

    Is there anything in TFP403 circuit that can be adjusted to make it work? I tried clock polarity it does not help.