Hi Team, seeking some support for a customer.
We use LMX2492 as frequency synthesizer for our VSAT BUCs.
We faced one problem:
At device start, microcontroller programs LMX2492 for desired frequency. After it waits for lock detect signal. If there is no lockdetect signal for some time LMX2492 is reprogrammed and next cycle is started.
Problem reveals when there is no lockdetect signal at all(we dont supply refernece clock). After some time lmx2492 "hangs" because of multiple reprogrammings. Charge pump becomes HI-Z, lockdetect signal becomes high. As microcontroller sees lockdetect signal it stops programming and stops. System hangs but we have no real PLL lock.
What can be reasons of that behavior?
Thank you in advance.
-Mark
