MT9044AP1 Zarlink Semiconductor, Inc., MT9044AP1 Datasheet - Page 18

• Manufacturer Part Number: MT9044AP1
• Description: Framer: Framer Circuit: T1/E1/OC3 System Synchronizer
• Manufacturer: Zarlink Semiconductor, Inc.

Applications
This section contains MT9044 application specific details for clock and crystal operation, guard time usage, reset
operation, power supply decoupling, Manual Control operation and Automatic Control operation.
Master Clock
The MT9044 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 ±100ppm. For applications requiring an accurate Freerun Mode, such as Bellcore GR-1244-CORE, the
tolerance of the master timing source must Be no greater than ±32ppm.
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 MT9044 will always equal ±230ppm.
For example, if the master timing source is ±100ppm, then the capture range will be ±130ppm.
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.
See AC Electrical Characteristics.
For applications requiring ±32ppm clock accuracy, the following clock oscillator module may be used.
CTS CXO-65-HG-5-C-20.0MHz
Frequency:
Tolerance:
Rise & Fall Time:
Duty Cycle:
The output clock should be connected directly (not AC coupled) to the OSCi input of the MT9044, and the OSCo
output should be left open as shown in Figure 9.
Crystal Oscillator - Alternatively, a Crystal Oscillator may be used. A complete oscillator circuit made up of a
crystal, resistor and capacitors is shown in Figure 10.
20MHz
25ppm 0C to 70C
8ns (0.5V 4.5V 50pF)
45% to 55%
MT9044
Figure 9 - Clock Oscillator Circuit
OSCo
OSCi
No Connection
Zarlink Semiconductor Inc.
MT9044
20MHz OUT
18
GND
+5V
+5V
0.1uF
Data Sheet