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LMK04832EVM: Output frequency at CLKout pins is not getting when EVM onboard external vco is used

User001
Prodigy 100 points
Part Number: LMK04832EVM
Other Parts Discussed in Thread: LMK04832

Hi Ti Team,

We are using Evm of LMK04832 and could not able to get the output frequency 122.88 at CLKout pins when onboard 122.88MHz cystal is used ( LMK is used as distribution network and Plls are disabled) . please see the attached configuration fileLMK_122.88MHz onboard VCXO.tcs.

kindly let me know what am i missing?

FYI: 1)observed 122.88MHz signal at input of LMK (43 and 44pins). 

2)observed all outputs if i have given external signal to CLKin1 (used as distributed Network/Plls are disabled) but not by using on board 122.88MHz onboard VCXO

  • +1
    TI__Genius 10995 points

    Hello,

    If you are trying to use the VCXO to output it's frequency in distribution mode, then this can only be done through the OSCout pin, as shown in the picture below with the red path. I have also tested this in lab and noticed an output only on the OSCout pin. Note that in the EVM, the OSCin pin is the same as what's being outputted from the VCXO back into the LMK04832.

    You can generate clock outputs at the CLKoutX/Y pins by using an external source, as you tested above, and as shown below with the green path. Hope this helps!

    Good luck,

    Andrea