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參數(shù)資料
| 型號： | MT9045 |
| 廠商： | Mitel Networks Corporation |
| 英文描述： | T1/E1/OC3 System Synchronizer(T1/E1/OC3 系統(tǒng)同步裝置（由一個數(shù)字鎖相環(huán)組成）) |
| 中文描述： | T1/E1/OC3系統(tǒng)同步器（T1/E1/OC3系統(tǒng)同步裝置（由一個數(shù)字鎖相環(huán)組成）） |
| 文件頁數(shù)： | 13/25頁 |
| 文件大?。?/td> | 104K |
| 代理商： | MT9045 |
Advance Information
MT9045
13
The output clock should be connected directly (not
AC coupled) to the OSCi input of the MT9045, and
the OSCo output should be left open as shown in
Figure 8.
Crystal
Oscillator may be used. A complete oscillator circuit
made up of a crystal, resistor and capacitors is
shown in Figure 9.
Oscillator
-
Alternatively,
a
Crystal
Figure 9 - Crystal Oscillator Circuit
The accuracy of a crystal oscillator depends on the
crystal tolerance as well as the load capacitance
tolerance. Typically, for a 20MHz crystal specified
with a 32pF load capacitance, each 1pF change in
load capacitance contributes approximately 9ppm to
the frequency deviation. Consequently, capacitor
tolerances, and stray capacitances have a major
effect on the accuracy of the oscillator frequency.
The trimmer capacitor shown in Figure 9 may be
used
to
compensate
for
accuracy is not a concern, then the trimmer may be
removed, the 39pF capacitor may be increased to
56pF,
and
a
wider
tolerance
substituted.
capacitive
effects.
If
crystal
may
be
The crystal should be a fundamental mode type - not
an overtone. The fundamental mode crystal permits
a simpler oscillator circuit with no additional filter
components and is less likely to generate spurious
responses. The crystal specification is as follows.
Frequency:
Tolerance:
Oscillation Mode:
Resonance Mode:
Load Capacitance:
Maximum Series Resistance:
Approximate Drive Level:
e.g., R1B23B32-20.0MHz
(20ppm absolute,
±
6ppm 0C to 50C, 32pF, 25
)
20MHz
As required
Fundamental
Parallel
32pF
35
1mW
TIE Correction (using PCCi)
When Primary Holdover Mode is entered for short
time periods, TIE correction should not be enabled.
This will prevent unwanted accumulated phase
change between the input and output.
For instance, 10 Normal to Holdover to Normal mode
change sequences occur, and in each case Holdover
was entered for 2s. Each mode change sequence
could account for a phase change as large as 350ns.
Thus, the accumulated phase change could be as
large as 3.5us, and, the overall MTIE could be as
large as 3.5us.
0.05ppm is the accuracy of Holdover Mode
50ns is the maximum phase continuity of the
MT9045 from Normal Mode to Holdover Mode
200ns is the maximum phase continuity of the
MT9045 from Holdover Mode to Normal Mode
(with or without TIE Corrector Circuit)
When 10 Normal to Holdover to Normal mode
change sequences occur without MTIE enabled, and
in each case holdover was entered for 2s, each
mode change sequence could still account for a
phase change as large as 350ns. However, there
would be no accumulated phase change, since the
input to output phase is re-aligned after every
Holdover to Normal state change. The overall MTIE
would only be 350ns.
Reset Circuit
A simple power up reset circuit with about a 50us
reset low time is shown in Figure 10. Resistor R
P
is
for protection only and limits current into the RST pin
during power down conditions. The reset low time is
not critical but should be greater than 300ns.
Figure 10 - Power-Up Reset Circuit
OSCo
56pF
1M
39pF
3-50pF
20MHz
MT9045
OSCi
100
1uH
1uH inductor: may improve stability and is optional
Phasehold
Phasestate
Phase
10
0.05
ppm
2
s
×
100
ns
=
=
50
ns
200
ns
250
ns
=
+
=
10
250
ns
100
ns
+
(
)
×
3.5
us
=
=
+3.3V
RST
R
P
1k
C
10nF
R
10k
MT9045
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MT9045AN | 制造商:Microsemi Corporation 功能描述: |
| MT9045AN1 | 制造商:Microsemi Corporation 功能描述:FRAMER E1/OC3/T1 3.3V 48SSOP - Rail/Tube 制造商:Microsemi Corporation 功能描述:T1/E1/OC3 SYSTEM SYNCHRONIZER |
| MT9045ANR1 | 制造商:Microsemi Corporation 功能描述:FRAMER E1/OC3/T1 3.3V 48SSOP - Tape and Reel 制造商:Microsemi Corporation 功能描述:iB FREE T1/E1/OC3 SYSTEM SYNCHRONIZER 制造商:Zarlink Semiconductor Inc 功能描述:FRAMER E1/OC3/T1 3.3V 48SSOP - Tape and Reel |
| MT9046 | 制造商:ZARLINK 制造商全稱:Zarlink Semiconductor Inc 功能描述:SONET/SDH Clock Multiplier PLL |
| MT9046AN | 制造商:Microsemi Corporation 功能描述: |
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