ZL30402
Data Sheet
FCS
Filtering Characteristic
Phase Slope
0
Filter corner frequency set to 1.1 Hz.
41ns
This selection meets requirements of G.813 Option 1 and GR-1244 stratum 3
clocks.
in 1.326ms
1
Filter corner frequency set to 0.1 Hz.
885ns/s
This selection meets requirements of G.813 Option 2, GR-253 for SONET stratum 3
and GR-253 for SONET Minimum Clocks (SMC).
Table 2 - Filter Characteristic Selection
RefSel: Reference Source Select. The RefSel (pin 47) input selects the PRI (primary) or SEC (secondary) input
as the reference clock for the Core PLL. The logic level at this input is sampled by the rising edge of F8o.
RefSel
Input Reference
0
1
Core PLL connected to the Primary Acquisition PLL
Core PLL connected to the Secondary Acquisition PLL
Table 3 - Reference Source Select
RefAlign: Reference Align. The RefAlign (pin 48) input controls phase realignment between the input reference
and the generated output clocks.
4.1.2 Status Pins
The ZL30402 has two dedicated status pins for indicating modes of operation. These pins are listed below:
LOCK. This output goes high when the core PLL is locked to the selected Acquisition PLL.
HOLDOVER - This output goes high when the Core PLL enters Holdover mode. The Core PLL will switch to
Holdover mode if the respective Acquisition PLL enters Holdover mode or if the mode select pins or bits are set to
Holdover (MS2, MS1 = 01).
4.2 Software Control
Software control is enabled by setting the HW pin to logic zero (HW = 0). In this mode all hardware control pins
(inputs) are disabled and status bits (outputs) are enabled. The ZL30402 has seventeen registers that provide all
the functionality available in Hardware control and in addition they offer advanced control and monitoring that is
only available in Software control (see Figure 6 "Hardware and Software Control options").
4.2.1 Control Bits
The ZL30402 has seven control bits as is shown in Figure 6 "Hardware and Software Control options". The first five
bits replace the five hardware control pins: MS2, MS1, FCS, RefSel and RefAlign and the last two bits support
recovery from Auto Holdover mode: AHRD and MHR. These bits are described in section 3.2.4.
In addition to the Control bits shown in Figure 6 "Hardware and Software Control options", the ZL30402 has a
number of bits and registers that are accessed infrequently or during configuration only e.g., Phase Offset
Adjustment or Master Clock Frequency Calibration.
19
Zarlink Semiconductor Inc.
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