Hi Team，
Good day，
When LMX2820 is used, it is found that after initial power-on (enabling instant calibration) and waiting for the completion of initialization, a required frequency is configured. After such operations, sometimes the output signal of LMX2820 is lock-out (the probability is about 10%). The detailed information is as follows:
(1) Output range of LMX2820 is 1414MHz~15626MHz, including multiple frequency bands;
(2) The application scenario requires the chip to enable real-time calibration to meet the frequency sweep requirement;
(3) Read back the rd_LD field status after losing the lock, and the result is 3 'b11;
(4) When lock-out occurs, it cannot be recovered by configuring registers or re-initialization, and the output is always in lock-out state and cannot be recovered;
(5) After the phenomenon of loss of lock occurs, it is re-initialized by external power failure, but everything returns to the origin, and there is still a probability of loss of lock;
(6) If there is no lock loss at the beginning, all subsequent operations are normal and no lock loss will occur. Therefore, the problem is concentrated in the initialization stage of power-on.
Ask the following questions about the above information:
A. Under what conditions does MX2820 enter the rd_LD = 3'11 state, what is the specific hardware state, and why is the result of reading back not rd_LD = 3'00 or rd_LD = 3'01 when the lock is lost?
B. Why does the configuration fail sometimes with the same configuration data and methods, that is, the above lockout situation?
C. Why does it enter the lock-out state and cannot be recovered?
Best Regards
James Man
