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ADS52J90EVM: single loop mode lmk04826 for 76.8 MSPS

Hyunok Kim
Prodigy 80 points

Part Number: ADS52J90EVM
Other Parts Discussed in Thread: LMK04826, ADS52J90

Hi 

I would like to  get 16ch-12bit-76.8 MSPS data with ADS52J90EVM

It needs two 76.8 MHz device clocks and  two19.2 MHz sysref clocks.

I want to generate the clocks using lmk04826 single loop mode which uses only OSCIn of 100MHz wihout CLKIN1

Because I have a trouble in using HMC-DAQ GUI, I generated tcs file for lmk04826 registers using TICS Pro

single-loop_76.8_19.2.tcs

Could you check whether it is correct or not?

 Thanks in advance

  • 0
    Prodigy 80 points

    I made config file for HMC-DAQ GUI from the tcs and ran HMC-DAQ.  But PLL2 of ADS52J90EVM doesn't lock  

  • 0 in reply to Hyunok Kim
    TI__Expert 7140 points

    Hi Hyunok,

    Thank you very much for reaching out to us.

    Please allow me some time to review your config file and understand the issue.

    I will get back to you before this Friday.

    Thanks & regards,
    Abhishek

  • 0 in reply to Abhishek Vishwa1
    TI__Expert 7140 points

    Hi Hyunok,

    I reviewed the .tcs file you shared and I think the reason why the PLL2 of the LMK04826 device was not getting locked was the setting of N_CAL as highlighted in the figure shown below.

    It should be equal to the N divider value. I have updated the same and the PLL2 block is not showing any red error. 

    Can you try with the attached .tcs file and check whether now the PLL2 is getting locked or not.

    Let me know if it works for you.

    Thanks & regards,

    Abhisheksingle-loop_76.8_19.2_UPDATED.tcs

  • 0 in reply to Abhishek Vishwa1
    Prodigy 80 points

    Thank you for your update

    When I said "PLL2 of ADS52J90EVM doesn't lock", I jurged it from watching LMK_PLL2_LOCK led.
    According to user guide, the led must be turn on when pll2 is locked. But it didn't illuminate

    This time, with my original cfg file, I measured sysref frequency with oscilloscope and confirmed it has the correct frequency value

    Then I did the same thing with your update. The result was the same as mine
    But your update didn't make the led turn on, either

    I confirmed PLL2_LD_MUX = PLL2_DLD and PLL2_LD_TYPE = Output (Push-Pull) in the settings.

    Can I ignore that the led is not lit?

    sysref clocks which I observed from oscilloscope seemed a  little noisy

    Is it due to loop filter parameters not adjusted? 

    I used PLLAltium simulation tool to get the adjusted loop filter parameters 

    By File -> Interface with TICSPro -> Load TICPro File, single-loop_76.8_19.2_UPDATED.tcs was loaded

    Then I checked "Auto" and push down "Calculate Loop Filter"

    This is the result

    The push button had changed the values of C1, C2 and R2. The original values were 0.047nF, 3.9 nF and 0.62 kOhm respectively

    From that, I guess  C1, C2 and R2 are C7, C6 and R16 in evm board respectively 

    Could you confirm it?

  • 0 in reply to Hyunok Kim
    TI__Expert 7140 points

    Hi Hyunok,

    Thanks for doing the tests.

    Since your issue is more related to LMK04826 device, I have assigned this thread to Ajeet who is the expert on the LMK device.

    I take care of the ADS52J90 device, so I think we both will be able to help you further.

    Thanks & regards,
    Abhishek