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參數(shù)資料
| 型號： | MT9042C |
| 廠商： | Mitel Networks Corporation |
| 英文描述： | Multitrunk System Synchronizer |
| 中文描述： | Multitrunk系統(tǒng)同步 |
| 文件頁數(shù)： | 14/28頁 |
| 文件大?。?/td> | 113K |
| 代理商： | MT9042C |
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MT9042C
Advance Information
14
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 MT9042C, and
the OSCo output should be left open as shown in
Figure 9.
20MHz
25ppm 0C to 70C
8ns (0.5V 4.5V 50pF)
45% to 55%
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.
Figure 10 - 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 10 may be
used to compensate for capacitive effects. If
accuracy is not a concern, then the trimmer may be
removed, the 39pF capacitor may be increased to
56pF, and a wider tolerance crystal may be
substituted.
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:
20MHz
As required
Fundamental
Parallel
Load Capacitance:
Maximum Series Resistance:
Approximate Drive Level:
e.g., CTS R1027-2BB-20.0MHZ
(
±
20ppm absolute,
±
6ppm 0C to 50C, 32pF 25
)
32pF
35
1mW
Guard Time Adjustment
AT&T TR62411 recommends that excessive switching
of the timing reference should be minimized. And that
switching between references only be performed when
the primary signal is degraded (e.g., error bursts of 2.5
seconds).
Minimizing switching (from PRI to SEC) in the
MT9042C can be realized by first entering Holdover
Mode for a predetermined maximum time (i.e., guard
time). If the degraded signal returns to normal before
the expiry of the guard time (e.g., 2.5 seconds), then
the MT9042C is returned to its Normal Mode (with no
reference switch taking place). Otherwise, the
reference input may be changed from Primary to
Secondary.
Figure 11 - Symmetrical Guard Time Circuit
A simple way to control the guard time (using
Automatic Control) is with an RC circuit as shown in
Figure 11. Resistor R
P
is for protection only and
limits the current flowing into the GTi pin during
power down conditions. The guard time can be
calculated as follows.
V
SIH
is the logic high going threshold level for the
GTi Schmitt Trigger input, see DC Electrical
Characteristics
OSCo
56pF
1M
39pF
3-50pF
20MHz
MT9042C
OSCi
100
1uH
1uH inductor: may improve stability and is optional
GTi
C
10uF
R
150k
MT9042C
GTo
+
R
P
1k
guardtime
RC
VDD
–
VDD
VSIH
---------------------------------
ln
×
=
guardtime
RC
0.6
×
≈
guardtime
150
k
10
u
×
0.6
0.9
s
=
×
≈
example
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MT9042CP | Multitrunk System Synchronizer |
| MT9042 | Global Digital Trunk Synchronizer |
| MT9042AP | Global Digital Trunk Synchronizer |
| MT9044 | T1/E1/OC3 System Synchronizer |
| MT9044AL | T1/E1/OC3 System Synchronizer |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MT9042CP | 制造商:Microsemi Corporation 功能描述: 制造商:Mitel Networks Corporation 功能描述: |
| MT9042CP1 | 制造商:Microsemi Corporation 功能描述:SYNCHRONIZER 28PLCC - Rail/Tube 制造商:Microsemi Corporation 功能描述:PB FREE MULTITRUNK SYSTEM SYNCHRONIZER 制造商:Zarlink Semiconductor Inc 功能描述:SYNCHRONIZER 28PLCC - Rail/Tube 制造商:Zarlink Semiconductor Inc 功能描述:PB FREE MULTITRUNK SYSTEM SYNCHRONIZER |
| MT9042CPR1 | 制造商:Microsemi Corporation 功能描述:SYNCHRONIZER 28PLCC - Tape and Reel 制造商:Zarlink Semiconductor Inc 功能描述:SYNCHRONIZER 28PLCC - Tape and Reel |
| MT9043 | 制造商:ZARLINK 制造商全稱:Zarlink Semiconductor Inc 功能描述:T1/E1 System Synchronizer |
| MT9043AN | 制造商:Microsemi Corporation 功能描述: |
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