zl50031 Zarlink Semiconductor, zl50031 Datasheet - Page 23

• Manufacturer Part Number: zl50031
• Description: Flexible 4 K X 2 K Channel Digital Switch With H.110 Interface And 2 K X 2 K Local Switch
• Manufacturer: Zarlink Semiconductor

16.0
16.1
The DPLL accepts two simultaneous reference input signals and operates on their rising edges. Either the primary
reference (PRI_REF) signal or the secondary reference (SEC_REF) signal can be selected to be the reference
signal (REF) to the PLL circuit. The appropriate frequency mode input (either FREQ_MOD_PRI or
FREQ_MOD_SEC) is selected to be the input of the PLL circuit. The selection is done by the State Machine Circuit
based on the current state.
The FREQ_MOD_PRI and the FREQ_MOD_SEC are 2-bit wide inputs which reflect the value in the FP1-0 and
FS1-0 bits of the DOM1 register. The primary and the secondary references operate independently from each other
and can have different frequencies. Switching the reference from one frequency to another does not require the
device reset to be applied. Table 19 on page 44 shows input frequency selection for the primary and secondary
reference respectively.
(Selected by FDM0-1 bits in DOM2)
FREQ_MOD_SEC
(Selected by SP3-0 bits
(Selected by SS3-0 bits
FREQ_MOD_PRI
(FP1-0 bits in DOM1)
C20i
(FS1-0 bits in DOM1)
(RPS bit in DOM1)
AUTODETECT
SEC_LOS Pin
PRI_LOS Pin
in DOM1)
in DOM1)
SEC_REF
Reference Select and Frequency Mode MUX Circuits
DPLL Functional Description
REF_SEL
PRI_REF
CLK80M
APLL
Reference
Reference
Reference
Frequency
Monitor
Monitor
Select
MUX
Mode
MUX
Secondary ref fail
Figure 6 - DPLL Functional Block Diagram
Primary ref fail
Zarlink Semiconductor Inc.
REF_SELECT
FREQ_MOD
REF
LOS_SEC
ZL50031
LOS_PRI
FRAME_A_i
FRAME_B_i
23
HOLDOVER_RESET
(POS0-6 bits in DPOA)
SKEW_CONTROL
Machine
(Fig 6)
(SK0-2 bits in DPOA)
PHASE_OFFSET
(MRST bit in DOM2)
(HRST bit in DOM2)
State
MTIE_RESET
Select
Frame
MUX
MTIE_START
MTIE_DONE
HOLDOVER
FRAME
C8_A_i
C8_B_i
(Fig 8)
PLL
and Frame
and Frame
CT Clock
CT Clock
Monitor
Monitor
Data Sheet
CT_FRAME
C32/64
CT_C8
C1M5o
(
(
(
(
FRAME_A_o
FRAME_B_o
C8_A_o
C8_B_o
or
or
FAIL_A
FAIL_B
)
)
)
)