SNAS835A September 2022 – February 2025 LMK5B33414
PRODUCTION DATA
Typically phase cancellation is enabled during hitless switching to prevent a phase transient (phase hit) from immediately propagating to the outputs when switching between two frequency-locked reference inputs with a fixed phase offset. The phase cancellation persists indefinitely in the use case scenario when phase slew is not enabled commonly referred to as phase buildout. The inputs are frequency-locked when the inputs have the same exact frequency (0ppm offset), or have frequencies that are integer-related and can each be divided to a common frequency by integers. The hitless switching specifications (tHITLESS and fHITLESS) are valid for reference inputs with no wander. In the case where two inputs are switched but are not frequency-locked, the output smoothly transitions to the new frequency with reduced transient.