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LMK5B12204: Loss of lock DPLL

fumiya tanaka
Prodigy 80 points
Part Number: LMK5B12204
Other Parts Discussed in Thread: AM6411

Tool/software:

Hello,

I am trying to output a 27MHz clock from lmk5b12204 PLL2, but the read value of R14 Register is 0xD0 and the DPLL is not locked.

I am loading the attached tcs file with TICS Pro and writing the registers of lmk5b12204 via I2C.

I would like to find out why the DPLL does not lock. Could you please check if there are any problems with the TICS Pro settings or the register write values ​​of lmk5b12204?

For reference, when the DPLL is not locked, R13 = 0x00, R14 = 0xD0, R167 = 0x00, and R411 = 0x00.

PPS is output from the CPU.

CPU:AM6411

Clock Synthesizer: lmk5b12204

xo :19.2MHz 0.5ppm

Thank you,
Tanaka

test5_1PPS_default_modify.tcs

  • 0
    TI__Genius 11915 points

    Hi Tanaka,

    What version of TICS Pro are you using? It looks like the reference is not being validated based on the R411 value.

    Can you please share an oscilloscope shot of the 1PPS input? Is the input a 50% duty cycle signal?

    Let me get back to you next week after testing your config.

    Regards,

    Jennifer

  • 0 in reply to Jennifer Bernal
    Prodigy 80 points

    Hello Jennifer,

    The version of TICS Pro is v1.7.7.5.

    The PPS duty cycle is set to 50%.

    I have attached a PPS waveform image confirmed with an oscilloscope.

    ・Rising edge

    ・Falling edge

    As additional information, when writing to the lmk5b12204 registers (R0 to R352) via I2C, using single write instead of block write made a difference.
    When I used the attached test3.tcs file and set the register write to single write, the results became R13 = 0x00, R14 = 0xC0, R167 = 0x01, and R411 = 0x04.
    However, the DPLL is still not locked.
    Therefore, I would like to ask you to check that there are no problems with the settings in the test3.tcs file.
    (Please delete test5_1PPS_default_modify.tcs.)

    test3.tcs

     

    Thank you,
    Tanaka

  • 0 in reply to fumiya tanaka
    TI__Genius 11915 points

    Hi Tanaka,

    Did you click on the Run Script button? The button is found on the DPLL page and generates the DPLL settings required. The button needs to be pressed because the XO input frequency you are using is different than the one used in Default Configuration.

    MATLAB Runtime R2015 v9 is required for the Run Script operation.

    I have clicked on the Run Script with your test3.tcs. Please try again with this file:

    test3_LMK5B12204_run_script.tcs

    Regards,

    Jennifer

  • 0 in reply to Jennifer Bernal
    Prodigy 80 points

    Hello Jennifer,

    I tried clicking the Run Script button on my test3.tcs and retesting, but the DPLL did not lock.
    Even with test3_LMK5B12204_run_script.tcs, DPLL did not lock.

    Thank you,
    Tanaka