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參數資料
| 型號： | L8575 |
| 英文描述： | Dual-Resistive,Low-Cost Subscriber Line Interface Circuit(SLIC) |
| 中文描述： | 雙電阻，低成本用戶線接口電路（SLIC） |
| 文件頁數： | 16/36頁 |
| 文件大?。?/td> | 633K |
| 代理商： | L8575 |
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L8575
Dual-Resistive, Low-Cost SLIC
Advance Data Sheet
March 1997
16
Lucent Technologies Inc.
Applications
General
The L8575 is a dual (channels A and B) subscriber line
interface circuit (SLIC). Each channel operates inde-
pendently such that no interaction occurs between the
channels. The following description applies to both
channels though the description may refer to only a sin-
gle channel. Some circuits, such as reference circuits
which do not impact interchannel crosstalk, are com-
mon to both channels.
The L8575 device supplies a precise differential current
to the Tip/Ring pair (via PT and PR) as a function of
analog signal voltages on IRP and VRN. However, the
current drivers connected to PT and PR are not
designed to supply dc feed current to the loop. Two
external resistors (typically 300
), connected to office
battery and ground, must be used in conjunction with
the L8575 SLIC to provide dc loop current. These resis-
tors will primarily determine the longitudinal balance of
the line feed; thus, they must be matched appropriately
to meet the longitudinal balance requirements (0.4%
for 50 dB balance).
These resistors also have a significant impact on the
termination impedance of the SLIC. Feedback, using
external components, allows the user to adjust the ter-
mination impedance from the intrinsic 600
of the feed
resistors to most ITU-T recommended complex termi-
nation impedances. Since the L8575 does not supply
dc to the loop, outputs PT and PR can be coupled to
the Tip and Ring through a resistance high enough to
allow for simple lightning protection of the drivers. How-
ever, the resistance must be low enough to achieve the
coupling of sufficient ac signals to the Tip and Ring
from the available power supply. Since the Tip and Ring
drivers are current sources, the value of the resistance
is arbitrary and does not affect the performance of the
SLIC. A minimum value of 1400
(1.4 k
)
is required
for protection purposes.
The L8575 also senses the Tip voltage, Ring voltage,
and differential Tip/Ring voltage via the TS and RS
sense inputs. The differential dc voltage is used inter-
nally for switchhook detection. The Tip and Ring volt-
ages are also used internally to detect faults on Tip and
Ring. Both detector thresholds are preset internally.
The status of each detector is monitored at pin DO by
reading the 8-bit serial shift register. The differential
Tip/Ring ac signal appears on analog output XMT.
The L8575 also includes:
I
Per-channel ring-trip detectors, loop closure detec-
tors.
I
Six relay drivers (three per channel).
I
8-bit serial-to-parallel and parallel-to-serial logic
interface.
I
Per-channel circuits which eliminate the battery
noise that is coupled to the Tip and Ring through the
dc feed resistors.
I
Fault detection.
I
Zero ring voltage detection.
Resistor Module
The L8575 requires certain external resistors at the Tip
and Ring interface. Because of matching and protec-
tion requirements, one of the most economical options
recommended to implement these registers is in a thick
film resistor module. A schematic and a brief descrip-
tion of the function of each of these resistors is given in
Figure 4. Note that Microelectronic Modules Corpora-
tion* MMC A31A8575AA Thick Film resistor module is
an application-specific resistor module designed for
use with the L8575 SLIC. The values, tolerance, match-
ing, and power rating of the MMCA31A8575AA mod-
ule are given in Table 10.
Resistors R
1
and R
2
are the dc feed resistors. R
1
is
connected from battery to Ring, and R
2
is connected
from Tip to ground. The dc loop current is fed to the
subscriber loop via these resistors. These resistors will
set the dc I/V template of the line circuit with the I/V
template being linear with a –1/600
slope. No con-
stant current region at short dc loops is provided by
resistors R
1
and R
2
, or the L8575 SLIC.
* For additional information, contact Microelectronic Modules
Corporation (MMC), 2601 S. Moorland Rd., New Berlin, WI 53151:
U.S.A: (414) 785-6506
FAX Number: (414) 785-6516
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相關代理商/技術參數 |
參數描述 |
|---|---|
| L8576B | 制造商:AGERE 制造商全稱:AGERE 功能描述:Dual Ringing SLIC |
| L8576BP | 制造商:Alcatel-Lucent 功能描述: 制造商:LUCENT 功能描述: |
| L85J250E | 制造商:Ohmite Mfg Co 功能描述: |
| L8601-01 | 制造商:HAMAMATSU 制造商全稱:Hamamatsu Corporation 功能描述:90KV MICROFOCUS X-RAY SOURCE |
| L8605 | 制造商:Leviton Manufacturing Co 功能描述: |
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