• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 46 subscribers
  • Views 817 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.

TSW38J84EVM external clock

Andre Prata
Prodigy 230 points
Other Parts Discussed in Thread: LMK04828, TRF3722

Hi all,

I am using TSW38J84EVM and I would like to configure the external clock capabilities.

As explained in the EVM user guide I want to operate the LMK04828 in the clock divider mode by supplying the fastest required clock, ie, the DAC output sampling rate. Additionally, I want to remove the JP2 of the external VCXO and use the LMK04828 to generate the OSCoutput for the TRF3722 mixer.

In my case I want to operate the DAC at an input sampling of 614.4MHz with an interpolation factor of 4. Therefore, the fastest required clock will be 2.4576 GHz, which I am supplying via the SMA J17.

I have tried to configure the LMK0428 but so far I have not been successful. The following screenshots present the configuration that I have tried.

In this configuration I have considered that the TRF3722 reference that will now be given by the CLKout6 , ie,  FsDAC/24 = 102.84MHz. Is this correct?

Can you please provide an example with screenshots of the GUI for this scenario? Or tell me what is wrong in my configuration?

Additionally what should be the power of the clock provided in the SMA J17?

Thanks!

Best Regards,

André

  • 0
    TI__Guru* 78404 points
    Andre,
    you are correct that the OSCOUT of the LMK04828 will take the divided down copy of the CLKOUT6 to the refin of the TRF3722. You may want to probe the OSCOUT port with scope to see if the actual 102.48MHz clock is coming out. Simply press the "Program TRF3722" button to program and re-init the TRF3722 to see if it will lock.
    The LMK04828 CLKINx port has max of 2.4Vpp of input swing requirement. You may refer to page 10 of the LMK04828 datasheet for detail.
    For further questions regarding the LMK04828 setup, please contact the forum support under CLOCK solutions.
    -Kang
  • 0 in reply to Kang Hsia
    Prodigy 230 points
    Hi Kang.

    With this configuration there is no lock at the TRF3722.

    Can you please confirm if the configuration is correct or try yourself in a board?
    An example could also be interesting.

    Additionally, I have a rev.B TSW38J84 board.

    Thank you very much for your availability.

    Best Regards,
    André
  • 0 in reply to Kang Hsia
    Prodigy 230 points
    Hi Kang,

    I also measured the OSCOUT port with a scope. Using the the onboard option I have seen the crystal clock of 122.88MHz. With the option I am trying I did not see any clock. So probably, something is wrong in the configuration...
    Can you help me with that?

    Thanks again.

    Best Regards
    Andre