zl30407qcc Zarlink Semiconductor, zl30407qcc Datasheet - Page 40

• Manufacturer Part Number: zl30407qcc
• Description: Sonet/sdh Network Element Pll
• Manufacturer: Zarlink Semiconductor

5.3
The Master Crystal Oscillator and its programmable Master Clock Frequency Calibration register (see Table 19,
Table 20, Table 21, and Table 22) are described in Section 3.5 "Master Clock Frequency Calibration Circuit", on
page 20. Programming of this register should be done after the system has been powered long enough for the
Master Crystal Oscillator to reach a steady operating temperature. When the temperature stabilizes the crystal
oscillator frequency should be measured with an accurate frequency meter. The frequency measurement should be
substituted for the f
where f
Example 1: Calculate the binary value that must be written to the MCFC register to correct a -1 ppm offset of the
Master Crystal Oscillator. The -1 ppm offset for a 20 MHz frequency is equivalent to -20 Hz:
Example 2: Calculate the binary value that must be written to the MCFC register to correct a +2 ppm offset of the
Master Crystal Oscillator. The +2 ppm offset for 20 MHz frequency is equivalent to 40 Hz:
5.4
Figure 15 "Power Supply Filtering" presents a complete filtering arrangement that is recommended for applications
requiring maximum jitter performance.
MCFC = 45036 * (-f
MCFC = 45036 * 20 = 900720 = 00 0D BE 70 H
Note: Correcting the -1 ppm crystal oscillator offset requires +1 ppm MCFC offset.
MCFC = 45036 * (-40) = -1801440 = FF E4 83 20 H
Programming Master Clock Oscillator Frequency Calibration Register
Power supply filtering
offset
C5
is the crystal oscillator frequency offset from the nominal 20 000 000 Hz frequency expressed in Hz.
GND
VDD
offset
variable in the following equation.
offset
62
64
68
70
72
74
76
66
78
80
60
)
2
58
4
56
6
54
ZL30407
Figure 15 - Power Supply Filtering
C1
8
52
10
C4
Zarlink Semiconductor Inc.
50
12
ZL30407
48
C2
14
46
40
16
44
18
42
20
40
38
36
34
32
30
28
26
24
22
GND
VDD
AVDD
GND
GND
C1, C2, C3, C4, C5 = 0.1 µF (ceramic)
FB - Ferrite Bead = BLM21A601R (Murrata)
C3
C6
FB
C6, C7 = 1 µF (ceramic)
C7
GND
VDD
Data Sheet