SNAS740B October 2017 – January 2019 LMX2572
PRODUCTION DATA.
The SYNC pin allows the user to synchronize the LMX2572 such that the delay from the rising edge of th OSCin signal to the RF output signal is deterministic. Phase synchronization is especially useful if there are multiple LMX2572 devices in a system and it is desirable to have all the RF outputs aligned in phase.
Initially, the devices are locked to the input but are not synchronized. The user sends a synchronization pulse that is re-clocked to the next rising edge of the OSCin pulse. After a given time, t1, the devices are synchronized. This time is dominated by the sum of the VCO calibration time, the analog settling time of the PLL loop, and the MASH_RST_COUNT, if used in fractional mode. After synchronization, both devices will have a deterministic delay of t2, related to OSCin.