zl50031 Zarlink Semiconductor, zl50031 Datasheet - Page 21

• 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

15.1.1
In the Primary Master Mode, the ZL50031 drives the “A Clocks” (C8_A_io and FRAME_A_io), by locking to the
primary reference (PRI_REF). The PRI_REF can be provided by one of the locally derived network reference
sources (LREF0-3), the CTREF1 input or the CTREF2 input. In this mode the ZL50031 has the ability to monitor the
primary reference. If the primary reference becomes unreliable, the device continues driving “A Clocks” in stable
Holdover Mode until it makes a Stratum 4 Enhanced compatible switch to the secondary reference (SEC_REF) for
its network timing. The secondary reference can be provided by one of the local network references (LREF0-3),
CTREF1 or CTREF2.
If the primary reference comes back or recovers, the ZL50031 makes a Stratum 4 Enhanced compatible switch
back to the original primary reference and the system returns to normal operation state.
If necessary, the ZL50031 can be prevented from switching back to the original primary reference by programming
the RPS bit in DOM1 register to give preference to the secondary reference.
While in the Primary Master mode, the ZL50031 attenuates jitter and wander above 1.52 Hz from the selected input
reference clock and generates all output clocks according to the DPLL jitter transfer function diagram on Figure 10
on page 31 and Figure 11 on page 32.
For the Primary Master mode selection, see Table 21, "ZL50031 Mode Selection - By Programming DOM1 and
DOM2 Registers" on page 49.
Primary Master Mode
LREF0-3
(8 kHz / T1 / E1)
Network Ref
PRIMARY
MASTER
Figure 5 - Typical Timing Control Configuration
LREF0-3
(8 kHz / T1 / E1)
Network Ref
SECONDARY
MASTER
CT_C8_A/CT_FRAME_A
CT_C8_B/CT_FRAME_B
Zarlink Semiconductor Inc.
ZL50031
CT_NETREF1
CT_NETREF2
21
LREF0-3
(8 kHz / T1 / E1)
Network Ref
SLAVE
LREF0-3
(8 kHz / T1 / E1)
Network Ref
SLAVE
Data Sheet