MT9046 Zarlink Semiconductor, MT9046 Datasheet - Page 18

• Manufacturer Part Number: MT9046
• Description: T1/E1 System Synchronizer with Holdover
• Manufacturer: Zarlink Semiconductor

Applications
This section contains MT9046 application specific details for clock and crystal operation, reset operation, power
supply decoupling, and control operation.
Master Clock
The MT9046 can use either a clock or crystal as the master timing source.
In Freerun Mode, the frequency tolerance at the clock outputs is identical to the frequency tolerance of the source
at the OSCi pin. For applications not requiring an accurate Freerun Mode, tolerance of the master timing source
may be
the master timing source must be no greater than
Another consideration in determining the accuracy of the master timing source is the desired capture range. The
sum of the accuracy of the master timing source and the capture range of the MT9046 will always equal 230 ppm.
For example, if the master timing source is 100 ppm, then the capture range will be 130 ppm.
Clock Oscillator - when selecting a Clock Oscillator, numerous parameters must be considered. This includes
absolute frequency, frequency change over temperature, output rise and fall times, output levels and duty cycle.
For applications requiring
FOX F7C-2E3-20.0 MHz
Frequency:
Tolerance:
Rise & Fall Time:
Duty Cycle:
The output clock should be connected directly (not AC coupled) to the OSCi input of the MT9046, and the OSCo
output should be left open as shown in Figure 8.
±
100 ppm. For applications requiring an accurate Freerun Mode, such as AT&T TR62411, the tolerance of
20 MHz
25 ppm 0C to 70C
10 ns (0.33 V 2.97 V 15 pF)
40% to 60%
±
32 ppm clock accuracy, the following clock oscillator module may be used.
Figure 8 - Clock Oscillator Circuit
MT9046
OSCo
OSCi
No Connection
Zarlink Semiconductor Inc.
±
MT9046
32 ppm.
20 MHz OUT
+3.3 V
+3.3 V
18
GND
0.1 uF
Data Sheet