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參數(shù)資料
| 型號： | LUCL8574DP-D |
| 英文描述： | L8574D Resistive Subscriber Line Interface Circuit(SLIC), Ring Relay,and Protector(SRP)for Long Loop and TR-57 Applications |
| 中文描述： | L8574D電阻用戶線接口電路（SLIC），環(huán)繼電器和保護（SRP）的為遠距離和TR - 57應用 |
| 文件頁數(shù)： | 28/36頁 |
| 文件大?。?/td> | 489K |
| 代理商： | LUCL8574DP-D |
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28
Lucent Technologies Inc.
Data Sheet
October 1998
Relay, and Protector (SRP) for Long Loop and TR-57 Applications
L8574D Resistive Subscriber Line Interface Circuit (SLIC), Ring
dc Characteristics
(continued)
V-I Characteristics
(continued)
In longer loops, the L8574 will operate in the linear
region of operation, and in short loops, to conserve
power, the L8574 will operate in the (fixed) current-limit
region of operation. A typical V-I characteristic for the
L8574 is shown in Figure 10 below.
12-3050.e (C)
Note: V
BAT1
= –48 V, V
BAT2
= –48 V; I
LIM
= 28 mA; R
DC
= 400
.
Figure 10. Loop Current vs. Loop Voltage
Loop Length
The loop range is calculated as follows:
R
L
= ({
|
V
BAT
|
– V
OHLIM
}/I
LIMIT
) – R
1
– R
2
Where:
R
L
is the dc resistance of the subscriber loop.
V
OHLIM
is the overhead or drop associated with the cur-
rent-limit circuit, typically 2.2 V.
I
LIMIT
is the minimum specified current that is required
at the maximum loop length, typically 18 mA.
|
V
BAT
|
is the minimum magnitude of the battery—
assume 43.2 V.
R
1
= R
2
= dc feed resistors = 200
.
R
L
= ({43.2 V – 2.2 V}/0.018 A) – 200
– 200
=
1877
.
ac Design
Codec Features and Selection Summary
There are four key ac design parameters:
I
Termination impedance
is the impedance looking
into the 2-wire port of the line card. It is set to match
the impedance of the telephone loop in order to mini-
mize echo return to the telephone set.
I
Transmit gain
is measured from the 2-wire port to
the PCM highway.
I
Receive gain
is done from the PCM highway to the
transmit port.
I
Hybrid balance
network
cancels the unwanted
amount of the receive signal that appears at the
transmit port.
At this point in the design, the codec needs to be select-
ed. The discrete network between the SLIC and the co-
dec can then be designed. Below is a brief codec
feature and selection summary.
First-Generation Codecs
These perform the basic filtering, A/D (transmit), D/A
(receive), and
μ
-law/A-law companding. They all have
an op amp in front of the A/D converter for transmit
gain setting and hybrid balance (cancellation at the
summing node). Depending on the type, some have
differential analog input stages, differential analog out-
put stages, and
μ
-law/A-law selectability. This genera-
tion of codec has the lowest cost. It is most suitable for
applications with fixed gains, termination impedance,
and hybrid balance.
Second-Generation Codecs
This class of devices includes a microprocessor inter-
face for software control of the gains and hybrid bal-
ance. The hybrid balance is included in the device. ac
programmability adds application flexibility and saves
several passive components. It also adds several I/O
latches that are needed in the application. It does not
have the transmit op amp, since the transmit gain and
hybrid balance are set internally.
L
0
10
20
50
0
20
30
40
50
LOOP VOLTAGE (V)
30
40
10
1
10 k
I
LIM
–1
R
DC1
–1
400
=
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LUCL8574DP-DT | L8574D Resistive Subscriber Line Interface Circuit(SLIC), Ring Relay,and Protector(SRP)for Long Loop and TR-57 Applications |
| LUCL8575BP | Dual-Resistive,Low-Cost Subscriber Line Interface Circuit(SLIC) |
| LUCL8575BP-TR | Dual-Resistive,Low-Cost Subscriber Line Interface Circuit(SLIC) |
| LUCL8576BP-D | Dual Ringing SLIC |
| LUCL8576BP-DT | Dual Ringing SLIC |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LUCL8574DP-DT | 制造商:AGERE 制造商全稱:AGERE 功能描述:L8574D Resistive Subscriber Line Interface Circuit(SLIC), Ring Relay,and Protector(SRP)for Long Loop and TR-57 Applications |
| LUCL8575BP | 制造商:AGERE 制造商全稱:AGERE 功能描述:Dual-Resistive,Low-Cost Subscriber Line Interface Circuit(SLIC) |
| LUCL8575BP-TR | 制造商:AGERE 制造商全稱:AGERE 功能描述:Dual-Resistive,Low-Cost Subscriber Line Interface Circuit(SLIC) |
| LUCL8576BP-D | 制造商:AGERE 制造商全稱:AGERE 功能描述:Dual Ringing SLIC |
| LUCL8576BP-DT | 制造商:AGERE 制造商全稱:AGERE 功能描述:Dual Ringing SLIC |
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