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LMK05318B: Can this device be used as a simple oscillator + distributor with divider?

John11513
Expert 5720 points
Part Number: LMK05318B


Tool/software:

Hi Experts,

I noted the on-chip BAW oscillator has good enough accuracy and jitter performance. I am wondering is it possible to operate this device in a simple oscillator + distributor with divider mode? (without any reference input and XO input.)

Thank you!

John

  • 0
    TI__Expert 5720 points

    Or, use VCO1 as reference clock for DPLL2, and synthersizes expected clock. 

  • 0 in reply to John11513
    TI__Expert 3135 points

    Hi John,

    LMK05318B has 1x DPLL and 2x APLLs.

    In APLL mode, APLL1 uses XO to provide output clocks, no reference needed. APLL2 can either use XO or cascade VCO1.

    In DPLL mode, DPLL control APLL1 numerator to sync with the reference.

    As APLL2 can cascade VCO1, technically, APLL2 can still generate output clocks. However, since APLL1 (VCO1) doesn't not have XO for VCO1 to reference the accuracy, the outputs from APLL2 are likely tuning with unexpected errors. Hence this method is not recommended.

    What is your clock plan? If you're looking for a reference-less device, LMK3H0102 is a reference-less BAW clock gen that could meet this requirement.

    -Riley

  • 0 in reply to Riley Nguyen
    TI__Expert 5720 points

    Hi Riley,

    Thank you for reply.

    What about no XO input, no reference input, VCO1 working in free running condition and provide reference for APLL2?

    Regards,

    John

  • +1 in reply to John11513
    TI__Expert 3135 points

    Hi John,

    VCO1 can provide the reference to APLL2, but since APLL1 doesn't have XO as the reference, VCO1 is tunning with error. Operating the device with no XO is not recommended.

    -Riley