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LMK05318B: Best output to put on status pins

Jason Haedt
Expert 4650 points
Part Number: LMK05318B

Tool/software:

Hello,

We are trying to determine if the LMK05318B primary reference is good and we need to output that on the status pins.  PRIREF_VALSTAT seems to be the right register to read but we can't see that as a status output pin.  

We’re currently assigning the status 1 output to “DPLL PRIREF Selected”.  Is there a better status to know if that selected input is actually being used?  I guess that in some situations, do we know if were still in holdover mode, even though we’ve selected primary reference on the status pins?  

 

Something like:

DPLL Holdover Active

DPLL Loss of Lock

DPLL Phase Lock Detected

Let me know your thoughts,

  • 0
    TI__Genius 16665 points

    Hi Jason,

    Yes, the "DPLL PRIREF Selected" signal can be selected to check if the PRIREF input is currently valid.

    To check Holdover, you would have to use another signal .

    DPLL Frequency Lock Detect (LOFL) is the best choice for knowing if the device is still in holdover or if a valid reference is present. You wouldn't be able to know which of the PRIREF or SECREF is valid , only that at least one of them is valid.

    I don't recommend using LOPL if you want to know about holdover because it is possible that the DPLL can be frequency locked (not in holdover) but not yet phase locked.

    Regards,

    Jennifer