ZL50010/GDC ZARLINK [Zarlink Semiconductor Inc], ZL50010/GDC Datasheet - Page 37

• Manufacturer Part Number: ZL50010/GDC
• Description: Flexible 512 Channel DX with Enhanced DPLL
• Manufacturer: ZARLINK [Zarlink Semiconductor Inc]

2.10.5
LOS Control uses the results from the reference monitors to influence the transition of the State Machine. The
outputs of LOS Control are affected by the choice of the failure detect mode (one of autodetect, forced primary, and
forced secondary modes chosen via the DOM register FDM1-0 bits) as shown in Table 15.
2.10.6
The State Machine manages the reference rearrangement process. The State Machine can be in one of the six
states shown as bubbles in Figure 27. Each bubble shows the state name and state number. Depending on the 3
bit LOS Control output {LOS_PRI, LOS_SEC, REF_SEL} shown in Table 15, the State Machine selects either
PRI_REF_INT or SEC_REF as the current reference. In autodetect mode, the State Machine transitions between
the states during reference rearrangement and switches the PLL circuit between normal and holdover operations.
When the DPLL goes from holdover to normal operation, the State Machine goes through the MTIE PRI or MTIE
SEC state to activate the MTIE circuit. The MTIE circuit prevents any significant phase shift at the PLL output clock
during the reference switch. Note that the PLL is still outputting holdover clock during the MTIE PRI or MTIE SEC
state.
In forced primary mode, the state machine will always stay in "Normal PRI" and never transition to "Holdover PRI".
In forced secondary mode, the state machine will always stay in "Normal SEC" and never transition to "Holdover
SEC".
The DHKR register ST2-0 bits report the state number. In autodetect mode, the ST2-0 bits will follow the state
transitions. In forced primary mode, ST2-0 is always 0. In forced secondary mode, ST2-0 is always 4.
Failure Detect Mode
Forced Secondary
Forced Primary
RESET Pin = 0
Autodetect
LOS Control Circuit
State Machine Circuit
1xx or x01
Holdover
PRI
Normal
PRI
reference monitor)
Table 15 - LOS Outputs in the Failure Detect Modes
x01
(from primary
2
FAIL_PRI
LOS_PRI
or
1x0
011
0
0
1
or
0x0
Figure 27 - State Machine Diagram
0x0 or 011
x01
xxx = {LOS_PRI, LOS_SEC, REF_SEL}
0x0 or x11
Zarlink Semiconductor Inc.
or
MTIE
PRI
100
ZL50010
reference monitor)
(from secondary
3
37
LOS_SEC
FAIL_SEC
1
0
MTIE
SEC
0x0 or 011
100 or x01
(1: secondary is preferred reference)
(0: primary is preferred reference)
7
100 or x01
(REFSEL bit in DOM)
REF_SELX
REF_SEL
0x0 or x1x
0
1
Holdover
Normal
SEC
SEC
Data Sheet
6
4