• State
  • Locked Locked
  • Replies 7 replies
  • Subscribers 21 subscribers
  • Views 170 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LMX2594: Questions regarding the SYNC option

Hany Assasa
Prodigy 10 points
Part Number: LMX2594
Other Parts Discussed in Thread: LMK04208

Tool/software:

Hello,

I have a question about the SYNC input functionality on the LMX2594. From what I understand, this input is used to synchronize the phase of multiple LMX2594 devices. In my setup, I’m working with the ZCU111 board from AMD/Xilinx, which includes both the LMK04208 and LMX2594 clocking ICs.

On the ZCU111 board, the MUXout pin of the LMX2594 is connected to an onboard LED and is configured to indicate PLL lock status. When the board is running normally, the LEDs are lit, showing that the PLLs are locked and the board is functioning as expected.

However, I noticed that the SYNC signal from the LMK04208 (coming out on CLKout3) was not active. Please refer to the attached figure that illustrates the ZCU111 clocking structure.

Interestingly, when I enabled CLKout3 and set its frequency to 110 MHz (the same as CLKout4), the LEDs turned off, suggesting that the lock detector now indicates a non-locked state for the LMX2594 PLLs.

Could you please help me understand why enabling CLKout3 affects the lock status in this way? Are there any additional configurations that I need to enable on the LMX2594?
I tried enabling VCO_PHASE_SYNC and setting INPIN_IGNORE to zero, but it did not work.

My goal is to enable the SYNC signal so that I can synchronize the LMX2594 PLLs using a 10 MHz reference input connected to CLKin1 of the LMK04208.

I’ve attached my configuration files for both the LMK04208 and LMX2594 as generated by TICSPro for your reference.

Thank you in advance for your support!

LMK_CLKout4_110MHz_CLKin1_10MHz_CLKout3_110MHz.tcsLMX_3520MHz.tcs

  • 0
    TI__Guru** 107660 points

    Hi Hany,

    Your LMK configuration file puts the device in distribution mode, I am afraid you have attached the wrong file.

  • 0 in reply to Noel Fung
    Prodigy 10 points

    Hi Noel,
    Thanks for your reply.
    Unfortunately, I am having issues with the latest TICS Pro v1.7.9.0. When I load the TCS file, the configurations do not show correctly. I used to have this issue when loading the HEX Register files.
    I will attach here another file that I have been using for a long time, and it works perfectly on my setup. In this file, CLKout3 is powered down. See a snapshot below:


    So in the file that I shared in my original question, CLKOut3 is powered on, and it is set to 110 MHz. This is the only change that you need to make on the LMK side.
    Please let me know if the new file works now.

    LMK_CLKout4_110MHz_CLKin1_10MHz.tcs

  • 0 in reply to Hany Assasa
    TI__Guru** 107660 points

    Hi Hany,

    Unfortunately, you were giving me another distribution mode configuration, I can also confirm this by comparing the content of the .tcs files.

    Anyway, maybe your problem is related to below:

    We can use the second method to resolve the problem.

    1. Program the Powerdown bit to enable CLKout3.

    2. Select LVDS from the pull-down menu.

  • 0 in reply to Noel Fung
    Prodigy 10 points

    Hi Noel,

    Could you please elaborate on what you mean by the distribution configuration? The TCS file I provided has been working perfectly for me with my setup on the ZCU111, as I can generate various clocks to drive the LMK2594 and the FPGA fabric to achieve multi-tile synchronization.

    Regarding the steps that you mentioned, these were the exact steps that I followed in my initial attempt to enable the SYNC signal for the LMX2594, which resulted in a non-locked state for the LMX2594.

    For the text that you refer to, it is about the sequence of operations for programming the LMK, right? In my case, I am using the AMD/Xilinx System Controller GUI to program the whole registers of the LMK and LMX ICs in a sequential manner, i.e., I do not influence the execution or the order of execution.

    Let me know if something is unclear in my setup.

    Thanks.

  • 0 in reply to Hany Assasa
    TI__Guru** 107660 points

    Hi Hany,

    Distribution mode means PLL1 and PLL2 are not used, the input signal goes to the distribution path and fanout.

    This is the configuration I got after loading your configuration file.

  • 0 in reply to Noel Fung
    Prodigy 10 points

    Hi Noel,

    I see you have the same issue that I had at the beginning when I loaded the TCS file using TICSPro_1.7.9.0_27-May-2025. I have switched back to TICSPro_1.7.7.2_05-Feb-2024, which has been working perfectly for me, and I can change and load the configuration correctly.
    Using this version, these are the configurations that I see on my side with the TCS file (LMK_CLKout4_110MHz_CLKin1_10MHz.tcs) that I have shared with you.

    Could you please confirm which version you are using and if switching to the version that I stated will solve the issue?

    Thanks.

  • 0 in reply to Hany Assasa
    TI__Guru** 107660 points

    Hi Hany,

    I verified this, it is odd that the 2025 version TICS cannot load .tcs file correctly. The 2024 version TICS does not have this problem.

    Back to your problem, when you uncheck the Powerdown bit of channel 3, do you still get the clock signal from channel 4? I don't have the LMK04208 EVM, need your help to debug.