ZL30105_05 ZARLINK [Zarlink Semiconductor Inc], ZL30105_05 Datasheet - Page 14

• Manufacturer Part Number: ZL30105_05
• Description: T1/E1/SDH Stratum 3 Redundant System Clock Synchronizer for AdvancedTC TM and H.110
• Manufacturer: ZARLINK [Zarlink Semiconductor Inc]

When the incoming signal returns to normal (REF_FAIL=0), the DPLL returns to Normal mode with the output
signal locked to the input signal. Each of the monitors has a built-in hysteresis to prevent flickering of the REF_FAIL
status pin at the threshold boundaries. The precise frequency monitor and the timer do not affect the mode
(Holdover/Normal) of the DPLL.
If the device is set to Automatic mode (MODE_SEL1:0=11), then the state machine does not immediately switch to
another reference. If the single cycle and/or coarse frequency failures persist for more than 2.5 s or the precise
frequency monitor detects a failure, then the state machine will switch to another valid reference if that is available.
If there no other reference available, it stays in Holdover mode.
The precise frequency monitor’s failure thresholds are selected with the APP_SEL pins based on the ZL30105
applications, see Table 1. Figure 5, Figure 6 and Figure 7 show the out of range limits for various master clock
accuracies. It will take the precise frequency monitor up to 10 s to qualify or disqualify the input reference.
C20: 20 MHz master oscillator clock
C20: 20 MHz master oscillator clock
C20 Clock Accuracy
C20 Clock Accuracy
+32 ppm
-32 ppm
+50 ppm
-50 ppm
0 ppm
0 ppm
-115
Figure 5 - DS1 Out-of-Range Thresholds for APP_SEL1:0=00
-200
-100
Figure 6 - E1 Out-of-Range Thresholds for APP_SEL=01
-96
-83
-150
-75
-180
-130
-64
-150
-100
-100
-50
-51
-80
C20
-32
-32
Zarlink Semiconductor Inc.
-50
C20
-50
-50
-25
ZL30105
C20
C20
0
0
0
0
14
C20
50
50
50
25
C20
32
32
80
100
100
50
51
130
64
150
75
150
83
180
96
200
100
115
In Range
In Range
Out of Range
In Range
Frequency offset [ppm]
In Range
In Range
Out of Range
In Range
Frequency offset [ppm]
Out of Range
Out of Range
Out of Range
Out of Range
Data Sheet