ZL50015 ZARLINK [Zarlink Semiconductor Inc], ZL50015 Datasheet - Page 39

• Manufacturer Part Number: ZL50015
• Description: Enhanced 1 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
Automatic Reference Switching Without Preferences
Ref 0 failed
Ref 0 valid
Figure 21 - No Preferred Reference (Round Robin) with Ref 0-3 available
Holdover 0
Holdover 3
Free run
Ref 3
Start
All Ref failed
All Ref failed
Zarlink Semiconductor Inc.
Ref 2 and 3 failed
and (Ref 0 or Ref 1 valid)
and (Ref 2 or Ref 3 valid)
ZL50015
Ref 0 and 1 failed
39
All Ref failed
All Ref failed
Holdover 1
Holdover 2
Ref 1
Ref 2 failed
Ref 2 valid
Data Sheet
Ref 2