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CDCM6208: About output format.

Sho Ogane
Genius 5575 points
Part Number: CDCM6208

Hi all.

Please confirm the receiver device internal input circuit and receiver input requirment.
If we connect CDCM6208 output to this receiver device input, is HCSLformat correct? 

Best Regards,
Sho

receiver device input requirment.xlsx

  • 0
    TI__Genius 9920 points
    Hi Sho,
    For the single line swing requirement of the receiver, it should be in 200mV ~ 800mV. In CDCM6208 datasheet, the corresponding spec. is |Vod|.
    LVDS or CML type from CDCM6208 would be better for this application.

    But LVDS, LVPECL, CML types from CDCM6208 are all from CML drivers, so Vcm is (VDD_Yx_Yy - 0.x) V, which is close to CDCM6208 output VDD power supply. So please double check Vcm requirement for your receiver.

    If Vcm is not matched, we have to use AC coupling .
    If the receiver has internal bias (Vcm), the the AC coupling circuits would be very simple, only coupling caps are fine.
    If the receiver do not have internal bias, but still need a Vcm input, we have to rebuild a bias after AC caps, through (several kOhm) resistor dividers.

    Regards,
    Shawn
  • 0 in reply to Shawn Han
    Genius 5575 points

    Hi shawn-san

    Thank you very much for your quick response.
    The receiver device have internal AC coupling and 50 ohm, so please check the attached file.
    Is this format correct?

    Best Regards,
    ShoOutput fprmat.pdf

  • 0 in reply to Sho Ogane
    TI__Genius 9920 points

    Hi Sho-san,

    Internal AC coupling caps means Amplifier has its self bias. It is not good to DC coupling CML driver to 50 Ohm load to ground.

    So if you select LVDS or CML driver, please use an external AC coupling.

    If you select HCSL driver, put serial resistors (adjust 0~33Ohm according to amplitude requirements 200~800 mV, we could start with 15 Ohm for debug) at driver side, DC coupling to the receiver.

    Best Regards,

    Shawn

  • 0 in reply to Shawn Han
    Genius 5575 points

    Hi Shawn-san

    Thank you for your response.
    I understood your answer.

    Your support is very helpful for me, thank you very much!

    Best Regrads
    Sho