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DS90C185 serializer and DS90CF384 deserializer

Jaco Maritz
Prodigy 40 points

Other Parts Discussed in Thread: DS90C185, DS90CF384

DS90C185 serializer and DS90CF384 deserializer combination does not seem to work.

Have anyone managed to get this combination to work?
We see data and the clk seems to be correct but output bits set is not correct.

JM

  • 0
    TI__Expert 3050 points

    Hi Jaco,

    Can you provide a more detailed description of your issue?

    Do you have scope shots of the:

    • input clock and data to the DS90C185?
    • LVDS clcok and data input to the DS90CF384?
    • output data from the DS90CF384 measured at the inputs to your display/receiver?
    • power supply to the DS90C185?
    • power supply to the DS90CF384?

    Do you have schematics that you can share?

    Please list your operating pixel clock, interconnect type, interconnect length, color depth or any additional information that might be helpful for debugging your issue.

    Mike Wolfe

    DPS APPS / SVA

  • 0 in reply to Mike Wolfe
    Prodigy 40 points

    Hi Mike


    Thank you for replying so quickly please find attached schematics of both ser and des.

    6825.Serializer.pdf

    0572.De-Serializer.pdf

    What we have done is trying to get data through TXOUT0P+N and TXCLKOUTP+N with a twisted wire of 120mm long. When we measure the output on the deserializer RxOUT0 we measure data on this pin even when sending only one bit like on DIN[1]. If I can explain it like this we send the following data 0100000000000000000000000000 and we get 1000000000000000000000000000 we then change the input to 0010000000000000000000000000 and get        1000000000000000000000000000.

    I will try and send a scope capture tomorrow.

    Thank you again for the help.

    Jaco Maritz

  • 0 in reply to Jaco Maritz
    Prodigy 40 points

    Operating pixel clk = 27 Mhz

  • 0 in reply to Jaco Maritz
    Prodigy 40 points

    Hi Mike

    YESSSSSS we have managed to get the link working.

    We have replaced the capacitors on the serializer side with 0R resistors and swapped the CLK P and N signal.

    Never though that a 100nF capacitor can give us such trouble.

    We are using another pair DS99R101VS and DS99R102VS and their we must have the 100nF capacitors in otherwise it does not want to work.


    Have a great weekend.. :)

    Jaco Maritz

  • 0 in reply to Jaco Maritz
    TI__Expert 3050 points

    Hi Jaco,

    The caps will AC couple the serializer and deserializer. Unless you manage the ratio of ones and zeros through DC balance encoding you will run into signal integrity issues. These links are typically DC coupled, so removing the caps is a good move.

    Also, on your serializer board you should not have the 100 ohm differential termination resistors. Those resistors will reduce the amplitude of the differential waveform. You only need to have a single differential termination placed as close to the receiver inputs as possible.

    Mike Wolfe

    DPS APPS / SVA