ZHCSHN9A February 2018 – April 2018 LMK05028
PRODUCTION DATA.
Each DPLL reference clock input is independently monitored for input validation (qualification) before it is available for input selection by either DPLL. The reference monitoring blocks include amplitude, frequency, missing pulse, and runt pulse monitors. For a 1-PPS input, the phase valid monitor is supported and the frequency, missing pulse, and runt pulse monitors are not supported. A validation timer sets the minimum time for all enabled reference monitors to be clear of flags before an input is qualified.
The enablement and valid threshold for all reference monitors and validation timers are programmable per input. The reference monitors and validation timers are optional to enable, but critical to achieve optimal transient performance during holdover or switchover events and also to avoid selection of an unreliable or intermittent clock input. If a given detector is not enabled, it will not set a flag and will be ignored. The status flag of any enabled detector can be observed through the status pins for any reference input (selected or not selected). The status flags of the enabled detectors can also be read through the status bits for the selected input of each DPLL.