ZL50022GAC ZARLINK [Zarlink Semiconductor Inc], ZL50022GAC Datasheet - Page 40

• Manufacturer Part Number: ZL50022GAC
• Description: Enhanced 4 K Digital Switch with Stratum 4E DPLL
• Manufacturer: ZARLINK [Zarlink Semiconductor Inc]

12.1.3.1
When the DPLL is programmed to operate in Automatic mode without Preference (RCCR Register, PMS2-0 bits =
000), all references, REF0-3, will have equal importance. A circulating Round Robin selection sequence
determines the reference to be used as shown in Figure 21. The state machine basically searches for valid
reference in a circular order of REF0 -> REF1 -> REF2 -> REF3 -> REF0, etc.
Ref 0
Figure 21 - Automatic Reference Switching State Diagram with No Preferred Reference
Automatic Reference Switching Without Preferences
Ref 0 failed
Ref 0 valid
Holdover 0
Holdover 3
Free run
Ref 3
Start
All Ref failed
All Ref failed
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and (Ref 0 or Ref 1 valid)
Zarlink Semiconductor Inc.
and (Ref 2 or Ref 3 valid)
ZL50022
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40
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Holdover 1
Holdover 2
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Ref 2 valid
Data Sheet
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