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LMX2594EVM: Lock detect spcifications

user5941540
Intellectual 280 points

Part Number: LMX2594EVM

Hi,

I would like to know what are the lock detect specifications  ?

I have found in the datasheet the two types of ld_type et the ld_delay. For the ld_type, VCO calibration status means the end of the algorithm (right ?) but for the VCO Tuning voltage, there is no specific information. Can you tell me more about it ?

Thank you by advance

Stéphane

  • 0
    TI__Guru** 121260 points
    Hi There,

    For LD_TYPE = 0 (VCOcal), the MUXout pin will go HIGH after VCO calibration is finished, no matter if the PLL is locked or not.
    For LD_TYPE = 1 (VCOcal and Vtune), the MUXout pin will go HIGH only if (1)VCO calibration is finished, AND (2)Vtune voltage is within an acceptable range (silicon defaulted). That means, the PLL is usually locked if you see a HIGH from MUXout.
    We recommend set LD_TYPE = 1, which will return the status of the PLL.
  • 0 in reply to Noel Fung
    Intellectual 280 points
    Hi Noel,

    Thank you for your answer which confirm my assumption.
    Maybe I wasn't clear enough in my previous message, when you are saying "an acceptable range (silicon defaulted)", which values are defined as acceptable ? I have to confess I have no idea of what you are thinking with "silicon defaulted"
  • 0 in reply to user5941540
    TI__Guru** 121260 points
    Hi,

    The acceptable range is the threshold values determine the health of the Vtune voltage. These threshold values are hard-coded in the silicon, it is not accessible to the users. For LD_TYPE=1, we will check the Vtune status after vco calibration. If the returned code value (proportional to Vtune voltage) is within the thresholds, MUXout will return HIGH.