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LMX2594: LMX2594 biasing circuit

Carlo
Expert 7715 points
Part Number: LMX2594
Other Parts Discussed in Thread: CDCLVD1213, LMK00304, CDCLVD1204, CDCLVP1204

Hi team,

Good day.

Our customer is using the LMX2594, and the RFOUTB pins output the clock to the IN pins of a CDCLVD1213. Is adding a biasing circuit needed to ensure compatibility between the two devices when DC coupling since CDCLVD1213 has an LVDS input type?

Thank you in advance for your advice.


Regards,
Carlo

  • 0
    TI__Mastermind 28021 points

    Carlo,

    The LMX device needs resistor pull-up to 3.3 V to function properly.  As this is an open collector output, I'm not so sure it will work well if you try to force a DC voltage there.  We recommend that this be AC coupled.

    Regards,

    Dean

  • 0 in reply to Dean Banerjee
    Intellectual 530 points

    hi

    thank you for the recommendation.

    If this is the case, do you have any recommendations of Ti parts that are low latency, and would convert the LMX2594 open collector differential output to either LVDS or LVPECL, or CML?

    We are using this for Sysref, so the clock rate will not be high - in the 10 MHZ range, but it does need to have low latency.

    Thank you

  • 0 in reply to Trevor Fox
    TI__Genius 11900 points

    Hello Trevor,

    We have quite a few LVDS and LVPECL buffers that could be of use. The output from the LMX2594 will likely need to be AC-coupled and biased as per the buffers input requirements.

    1. LMK00304: selectable output format
    2. CDCLVD1204: LVDS 
    3. CDCLVP1204: LVPECL 

    Thanks,

    Vibhu