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TICSPRO-SW: TICSPRO in case of using LMK05318

Hirotaka Matsumoto
Guru 27585 points
Part Number: TICSPRO-SW
Other Parts Discussed in Thread: LMK05318

Hi all


Would you mind if we ask TICSPRO in case of using LMK05318?

<Question1>
On DPLL Frequency Lock Detect, how much value of Lock and Unlock threshold should we set?
What is "accuracy" used for? How much should we set?
And, is "Average=10" recommended number?



<Question2>
On BAW Lock Detect, if we use following XO and REF, should we set Lock threshold(ppm)=100?
-XO ppm error = 50ppm
-REF ppm error = 50ppm
What is "accuracy" used for? How much should we set?
And, is "Average=2" recommended number?




<Question3>
On Clock Input Validation (LOS) for input clock validation, in case of enable setting,
What is "accuracy" used for? How much should we set?
And, is "Average=2" recommended number?


If you have some document which is relation to these, could you share us?

Kind regards,

Hirotaka Matsumoto

  • +1
    TI__Expert 8585 points

    Hello Hirotaka,

    1. The DPLL is considered to be frequency locked if the frequency error between the VCO1 and the references is within the lock threshold. While the DPLL is frequency locked, it's considered to be frequency unlocked if the frequency error exceeds the unlock threshold. The accuracy and average are used to calculate the step size between the lock and unlock thresholds (lock/unlock threshold =  accuracy / average). For example if average is 10 and accuracy is 1, then unlock needs to be 10 times bigger than lock. The recommended lock ppm is 1. The recommended unlock ppm is 10. The recommended average is 10. The recommended accuracy is 1.

    2. The BAW (VCO1) is considered to be locked if the frequency error between the BAW and the XO is within lock threshold. Once the BAW is locked, it's considered to be unlocked if the frequency error exceeds the unlock threshold. The accuracy and average are used to calculate the step size between the lock and unlock thresholds (lock/unlock threshold =  accuracy / average). For example if average is 2 and accuracy is 1, then unlock needs to be 2 times bigger than lock. The recommended lock ppm is 5. The recommended unlock ppm is 10. The recommended average is 2. The recommended accuracy is 1.

    Since your XO has a 50 ppm error, please set lock to 50, unlock to 100, average to 2, and accuracy to 1.

    3. The reference frequency detector is only valid for PRIREF / SECREF frequencies >= 2 kHz. Frequency detection needs 4 parameters: valid threshold in ppm, invalid threshold in ppm, accuracy in ppm and average count. The PRIREF or SECREF is considered valid if the frequency error between PRIREF / SECREF and XO is within the valid threshold. While it's frequency valid, it's considered as frequency invalid if the frequency error exceeds the invalid threshold. The accuracy in ppm indicates how accurate the valid and invalid threshold can be. In other words, this is the resolution of valid and invalid threshold counters. The minimum average count is 2. Keep it as 2 unless the reference clock has too much wander and the DPLL loop bandwidth is too narrow. In that case, raise the average count to no more than 10. As mentioned, the '0-error' reference for frequency detection is the XO. In reality, of course, the XO frequency is not '0-error'. Therefore, the valid and invalid thresholds must take the XO ppm error into account. The minimum valid threshold should be max XO frequency error + max PRIREF / SECREF frequency error + accuracy in ppm. The minimum invalid threshold should be valid threshold + accuracy in ppm.

    Since your XO has 50 ppm error and your reference has 50 ppm error, please set lock to 110, unlock to 120 , accuracy to 10, average to 2.

    Regards,

    Kia Rahbar