Tool/software:
Hello expert, may I ask if the following external active crystal oscillator parameters meet the equipment requirements of LMK05318B-Q1? Thanks a lot.
Kind Regards
This thread has been locked.
If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.
Tool/software:
Hello expert, may I ask if the following external active crystal oscillator parameters meet the equipment requirements of LMK05318B-Q1? Thanks a lot.
Kind Regards
Hi Libin,
Technically, you can use it. Note that the max input voltage to XO pin is 2.6 Vpp so if the crystal voltage is higher than this, make sure your board have a voltage divider to keep the input within the voltage limit.
However, if you're using DPLL feature locking to 1PPS input signal, crystal is not stable enough to get phase lock.
Do you need to lock to low frequency signal with DPLL?
-Riley
Thank you so much! I would like to confirm again, is the feasibility of using DPLL features to lock to 1PPS input signal related to crystal voltage or others?
Kind Regards
Hi Libin,
DPLL helps lock to the input reference of any frequency from 1PPS to 800 MHz providing a long term stability to the system since it has holdover mode to keep the outputs stay in place in case the input is lost and re-locking once the input is recovered.
While in free-run mode (APLL only using XO reference), if XO is lost, the outputs will be tuning to incorrect frequencies.
Locking to 1PPS requires DPLL as it would need a small loop band width like 0.01 Hz to 0.1 Hz and with a crystal, the ppm is too large to be phase lock with small loop bandwidth.
-Riley