• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 21 subscribers
  • Views 396 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.

Original question:

LMK04610: sysref generation requirements

LMK04610: zero delay mode settings

Daniel Sternesky
Prodigy 40 points
Part Number: LMK04610

Hello,

I am having trouble getting the zero delay mode to work on the design I am trying to generate. In feedback mode (setting on PLL2 tab of TICS pro software) the PLL2 locks, and the output clocks are what I expect them to be. However if I switch it to OUTPUT5 or OUTPUT6 for zero delay mode, the output frequencies jump up ~4MHz and the PLL is no longer locked. I notice when I change this setting that the frequency in the PFD + LD box changes. Do I need to make the output of channel 5 or channel 6 match the output of the prescaler? What else do I need to consider for zero delay mode to operate?

Thanks,

Daniel

  • +1
    TI__Genius 12560 points

    Hi Daniel,

    To change from feedback path to zero delay loop back mode (OUTCH5 / OUTCH6), you need to ensure the OUTCH5_DIV / OUTCH6_DIV values to be "1", if you are not changing the PLL2_NDIV settings. Otherwise the total feedback divider values should be multiple of PLL2_NDIV and OUTCH5_DIV to lock the PLL2.

    Would be great, if you can share the used TICS Pro config file to look on the settings.

    Thanks!

    Regards,
    Ajeet Pal

  • 0 in reply to Ajeet Pal
    Prodigy 40 points

    Ajeet,

    This was indeed the issue. I am wondering, since we need to use zero delay mode in this application, and we need either clock5 or 6 to be at ~2GHz (the divide by 3 output of the prescaler), we will not be using this clock for anything else. Do we need to take some special care about what we do with the ouptut? I am assuming we can just terminate it to ground at 50 ohms. Is this the case?