Question: When an external mux is used with the need to have more that 2 inputs, do we have glitches passing from an input to another?
Answer: As the output derives from the DCXO, there will be no glitches on the output whether the input mux is internal or external, or even if the input reference fails completely. However, there will be a slight delay while the phase adjusts from the previous input to the new input, as seen in Figure 6 on page 5 of the CY23FS08 datasheet. This will not cause glitches, but will cause the phase/frequency to adjust for a short period.
The CY23FS08 will support glitch free operation in those situations, as the output derives from the DCXO, not directly from the input(s). So if there are only two external inputs, there is no need for an external mux, because the CY23FS08 already has a mux for the external inputs built in with a select pin to choose between the two. If there are more than two external inputs, then an additional external mux would be needed.
