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LMK05028: PLL cascade config

Prodigy 40 points

Replies: 4

Views: 81

Part Number: LMK05028

Dear All

I want to using LMK05028 DPLL1 to lock with 1PPS from REF_IN2 to generate clock 156.25MHz and DPLL2 lock to VCO1 FB to generate clock 122.88MHz

I choose DPLL2 mode is 2 loop TCXO, APLL, input reference is VCO1 FB but when I run script The TICS Pro said Run cancelled. DPLL(2) missing input assignment.

How to set up adjustment to solve this problem?

Thank you

GPS_1PPS.tcs

  • Hello,

    This is a current issue I'm working on correcting and make an updated TICS Pro release.  Do you have a time line for your setup?

    73,
    Timothy

    ____________________________________________________________________________________

    To design your own Clock Tree solution, visit WEBENCH Clock Architect​​​​
    More information Clock and Timing System products: http://www.ti.com/clock-and-timing/overview.html

  • In reply to Timothy T:

    Hi

    We will have first prototype in Oct.

    Also, I have another question. at initial lock to 1PPS the output frequency jump back and fourth a lot. it jump up to 156.43MHz, 156.06MHz then it start run around 156.25MHz with small step  until lock. 

    Does the big jump frequency is normal or i need ajust something?

    Is it fastlock behavior of the chip. Can i disable fastlock and have a clamp the Max, Min of output to avoid big diviation.

  • In reply to PHI TU:

    Hello,

    I don't expect big jumps with a lock to 1 PPS.  What is your loop bandwidth?  With a 1 PPS input, your loop bandwidth should generally be 0.1 Hz or less.

    73,
    Timothy

    ____________________________________________________________________________________

    To design your own Clock Tree solution, visit WEBENCH Clock Architect​​​​
    More information Clock and Timing System products: http://www.ti.com/clock-and-timing/overview.html

  • In reply to Timothy T:

    Hello

    My REF LBW is 0.02Hz and TCXO LBW is 200Hz

    I record a video, please take a look the link below. 

    https://onedrive.live.com/?authkey=%21ALh04hCeWO4ul3g&cid=F5CDC3471598649C&id=F5CDC3471598649C%21237678&parId=root&o=OneUp

    It start at 4 Sec, I press PDN button, it keep jumping about a minute then adjust with small step until lock.

    Thank.