Tool/software:
Hi,
I have an LMX2820 on my board seemingly running perfectly well (the output signal looks all good at various frequencies, with no frequency drift or any behavior indicating a loss of lock), but the LD output pin only goes high in One-Shot mode, not in continuous mode.
I am running the PLL with a single-ended input signal of 10 MHz and tested various output frequencies, e.g. 9 GHz, 14 GHz, 17 GHz, ...
It's even more confusing, that I have a second design including the LMX2820, which outputs continuously high on the LD pin with the same register values programmed to the chip as on the other board. It is the same design, except that the input signal is presented differentially instead of single-ended (but it keeps working if I disconnect one of the differential lines).
Could somebody please help me by providing possible reasons for this behavior? Thanks!
