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LMK04828BEVM: Problems with properly setup

user4867359
Prodigy 20 points
Part Number: LMK04828BEVM
Other Parts Discussed in Thread: CODELOADER, LMK04828, LMK04803,

Hello,

I have problems setting up the evalkit. I need the device for a clock distribution of 38.4MHz to at least 6 outputs. 

Used Software is Codeloader 4, because i can't find the Tic's Pro Software anywhere.

Now when I'm Powering up the board and connect it with the Usb2Any-device i can access the Configuration.

I've tried the default mode with 122.88MHz first and just wanted to configure all the Outputs to be at the same Phase. But with the delay options avaiable i can't do more than 5 to ten degrees change.

Also there is a problem with the Powerlevels. I've activated 4 Chanels at once and set them all to lvpecl16, but on the oscilloscope they all have different Levels.

What do I do wrong ? Is there any document about the Software and how to use it or the Evalkit and how to set it up for different usecases?

As I said I just want to have a 6-output 38.4MHz clkock with all channels in phase

kind regards

Raffael

  • 0
    TI__Genius 9920 points

    Hi Raffael,

    LMK04828 can't output frequency down to 38.4 MHz, because output divider only ranges 1~32, while minimum VCO frequency is 2370 MHz.

    LMK04803 or LMK40806 can output 38.4 MHz with dividers ranges 1~1045.

    1, The new GUI TICS Pro could be downloaded in below link http://www.ti.com/tool/ticspro-sw 

    Search key words "TICS Pro" in ti.com.

    Codeloader4 can also support LMK04828BEVM, but it would not be updated later. TI suggested to use TICS Pro.

    2, For output synchronization, we need trigger SYNC event in tab "SYSREF".

    Make sure 0 (not checked) on SYNC_DISx bits corresponding to those clock outputs need to be synced, refer to below capture from Codeloader. Toggle SYNC_POL bit in the top left of  the tab "SYSREF".

    For LMK04828 delay function, there are analog delay and digital delay. Analog delay use a fixed step around 25 ps except the first setting. Digital delay  steps a half or a cycle of "Clock distribution path" (VCO or VCO/divider frequency). So for your 5 ~ 10 degree phase on 122.88 MHz,  it may combine Analog and digital delay. It is hard to tuning. Above SYNC method is easier.

    3, The EVM may be mounted different termination resistors at outputs path. Make sure those outputs have the same loads.

    Regards,

    Shawn

     

  • 0 in reply to Shawn Han
    Prodigy 20 points

    Thanks Shawn!

    I don't need the Jitter-Cleaner, just the Distribution.

    After deactivating all the stuff I'm not using and setting up the sync, it now works well with 38.4MHz too

    regards,

    Raffael