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LMK05028EVM: EVM config setting and sync issue

Ryan Lee TW
Intellectual 506 points
Part Number: LMK05028EVM
Other Parts Discussed in Thread: LMK05028

Hi Teams,

My customer want to operate the LMK05028EVM in 2 loop mode which only enable the reference inputs and XO.

(They will use OCXO to replace XO in final design.)

 

Q1. When they are evaluating EVM performance, they found that only input is 25MHz which is default setting of EVM recommended can sync the output signal with input signal, but change the input frequency will not be able to sync, and D12/D13 will light up which means input/output are not sync.

Q2. About the phase noise, they are wondering which is better between 2 loop/3 loop mode? Because they intend to use 2 loop mode.

Thanks.

  • 0
    TI__Expert 8585 points

    Hello Ryan,

    1. Can you please provide me with your TICS Pro configuration in the .tcs file format? I will review it and determine what the issue could be.

    2. There won't be much of a difference in phase noise. The 3-loop mode just provides higher frequency stability in holdover mode.

    Regards,

    Kia Rahbar

  • 0 in reply to Kia Rahbar
    Intellectual 506 points

    Hello Kia,

    Please refer to the attached below for review.

    Thanks. 

    test1012.tcs

  • 0 in reply to Ryan Lee TW
    TI__Expert 8585 points

    Hello Ryan,

    When D12/D13 are ON, then DPLL1/2 are not locked. The Status 0 and Status 1 pins display the lock status not input/output synchronization. 

    In order to get your DPLLs to lock properly, please fill out steps 1-5 shown below as needed for your configuration and then press Run Script under step 6 to have the DPLL parameter be calculated properly. Once the DPLL parameters are calculated properly, the DPLL will lock.

    In order to sync the input and output frequencies, ZDM is required. Generally for ZDM, the input and output frequencies will need to be well related.  For example:
        * 25 MHz input and a 25 MHz output will be aligned.
        * 25 MHz input and a 50 MHz output will be aligned.

    Please see reference section 9.3.17 Zero-Delay Mode (ZDM) Configuration in the LMK05028 data sheet for more information on ZDM.

    Regards,

    Kia Rahbar