zl30410 Zarlink Semiconductor, zl30410 Datasheet - Page 19

• Manufacturer Part Number: zl30410
• Description: Multi-service Line Card Pll
• Manufacturer: Zarlink Semiconductor

5.1.2
The NORMAL to AUTO-HOLDOVER to NORMAL transition will usually happen when the Line Card loses its single
reference clock unexpectedly. The sequence starts with the reference clock transitioning from OK --> FAIL at a time
when ZL30410 operates in Normal mode (as is shown in Figure 10). This failure is detected by the active
Acquisition PLL based on the following FAIL criteria:
•
•
After detecting any of these anomalies on a reference clock the Acquisition PLL will switch itself into Holdover mode
forcing the Core PLL to automatically switch into the Auto Holdover state. This condition is flagged by LOCK = 0
and HOLDOVER = 1.
Frequency offset on 8 kHz, 1.544 MHz, 2.048 MHz and 19.44 MHz reference clocks exceeds ±30000 ppm
(±3%).
Single phase hit on 1.544 MHz, 2.048 MHz and 19.44 MHz exceeds half of the cycle of the reference clock.
RESET=1
RESET=1
Single Reference Operation: NORMAL --> AUTO HOLDOVER --> NORMAL
RESET
RESET
Figure 9 - Automatic Entry into Auto Holdover State and Recovery into Normal Mode
unconditional return from
unconditional return from
any state to Free-run
any state to Free-run
MS2,MS1=10 forces
MS2,MS1=10 forces
FREE-
FREE-
RUN
RUN
10
10
MS2,MS1=00
MS2,MS1=01
MS2,MS1=00
MS2,MS1=01
Figure 8 - Transition from Free-run to Normal mode
OR
OR
MS2,MS1=01 OR
MS2,MS1=01 OR
RefSel change
RefSel change
HOLD-
OVER
HOLD-
OVER
01
01
Zarlink Semiconductor Inc.
MS2,MS1=00
Ref: OK AND
MS2,MS1=00
Ref: OK AND
ZL30410
{AUTO}
{AUTO}
19
RefSel Change
RefSel Change
MS2,MS1=01
NORMAL
MS2,MS1=01
NORMAL
00
00
OR
OR
Ref: OK-->FAIL AND
Ref: OK-->FAIL AND
MS2,MS1=00
MS2,MS1=00
{AUTO}
{AUTO}
HOLD-
HOLD-
OVER
AUTO
OVER
AUTO
{AUTO}
Ref: FAIL-->OK AND
MS2,MS1=00
{AUTO}
Ref: FAIL-->OK AND
MS2,MS1=00
Data Sheet