MT9044
master clock may have a temperature coefficient of
±0.1ppm
per degree C. So a 10 degree change in
temperature, while the MT9044 is in Holdover Mode
may result in an additional offset (over the
±0.05ppm)
in frequency accuracy of
±1ppm,
which
is much greater than the
±0.05ppm
of the MT9044.
The other factor affecting accuracy is large jitter on
the reference input prior (30ms to 60ms) to the
mode switch. For instance, jitter of 7.5UI at 700Hz
may reduce the Holdover Mode accuracy from
0.05ppm to 0.10ppm.
Freerun Mode
Freerun Mode is typically used when a master clock
source is required, or immediately following system
power-up before network synchronization is
achieved.
In Freerun Mode, the MT9044 provides timing
synchronization signals which are based on
master clock frequency (OSCi) only, and are
synchronized to the reference signals (PRI
SEC).
and
the
not
and
Advance Information
The accuracy of the output clock is equal to the
accuracy of the master clock (OSCi). So if a
±32ppm
output clock is required, the master clock must also
be
±32ppm.
See Applications - Crystal and Clock
Oscillator sections.
10
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