9.3.7 Gapped Clock Support on Reference Inputs

Each DPLL supports locking to an input clock that has missing periods and is referred to as a gapped clock. Gapping a clock severely increases its jitter, so the device provides the high input jitter tolerance and low loop bandwidth necessary to generate a low-jitter periodic output clock. The resulting output will be a periodic non-gapped clock with an average frequency of the input with its missing cycles. The gapped clock width cannot be longer be than the reference clock period after the R divider (R_INx / f_INx). The reference input monitors should be configured to avoid any flags due to the worst-case clock gapping scenario to achieve and maintain lock. Reference switchover between two gapped clock inputs may violate the hitless switching specification if the switch occurs during a gap in either input clock.