- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄384587 > L7557 (Lineage Power) Low-Power SLICs （electronic subscriber loop interface circuits ）with Battery Switch(帶電池開關(guān)的低功耗用戶環(huán)路線接口電路（SLIC）) PDF資料下載
參數(shù)資料
| 型號： | L7557 |
| 廠商： | Lineage Power |
| 英文描述： | Low-Power SLICs （electronic subscriber loop interface circuits ）with Battery Switch(帶電池開關(guān)的低功耗用戶環(huán)路線接口電路（SLIC）) |
| 中文描述： | 低功耗SLIC組件（電子用戶環(huán)路接口電路）與電池開關(guān)（帶電池開關(guān)的低功耗用戶環(huán)路線接口電路電路（SLIC）） |
| 文件頁數(shù)： | 24/28頁 |
| 文件大?。?/td> | 753K |
| 代理商： | L7557 |
第1頁第2頁第3頁第4頁第5頁第6頁第7頁第8頁第9頁第10頁第11頁第12頁第13頁第14頁第15頁第16頁第17頁第18頁第19頁第20頁第21頁第22頁第23頁當前第24頁第25頁第26頁第27頁第28頁
24
Lucent Technologies Inc.
Data Sheet
January 2000
with Battery Switch
L7556, L7557 Low-Power SLICs
Applications
(continued)
ac Design
There are four key ac design parameters.
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 minimize echo return to
the telephone set.
Transmit gain
is measured from the
2-wire port to the PCM highway, while
receive gain
is
done from the PCM highway to the transmit port.
Finally, the
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
selected. The discrete network between the SLIC and
the codec can then be designed. Here 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 output stages,
and μ-law/A-law selectability. This generation of codecs
has the lowest cost. They are most suitable for applica-
tions with fixed gains, termination impedance, and hy-
brid 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 and also adds several I/O
latches that are needed in the application. However, it
does not have the transmit op amp, since the transmit
gain and hybrid balance are set internally.
Third-Generation Codecs
This class of devices includes the gains, termination
impedance, and hybrid balance—all under micropro-
cessor control. Depending on the device, it may or may
not include latches.
Selection Criteria
In the following examples, use of a first-generation
codec is shown. The equations for second- and third-
generation codecs are simply subsets of these. There
are two examples. The first shows the simplest circuit,
which uses a minimum number of discrete components
to synthesize a real termination impedance. The sec-
ond example shows the use of the uncommitted op
amp to synthesize a complex termination. The design
has been automated in a DOS based program, avail-
able on request.
In the codec selection, increasing software control and
flexibility are traded for device cost. To help decide, it
may be useful to consider the following. Will the appli-
cation require only one value for each gain and imped-
ance Will the board be used in different countries with
different requirements Will several versions of the
board be built If so, will one version of the board be
most of the production volume Does the application
need only real termination impedance Does the
hybrid balance need to be adjusted in the field
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| L7581 | Ringing Access Switch(振鈴存取開關(guān)) |
| L7582 | Ring Access Switch(振鈴存取開關(guān)) |
| L7583B | Line Card Access Switch(線卡存取開關(guān)) |
| L7583C | Line Card Access Switch(線卡存取開關(guān)) |
| L7583D | Line Card Access Switch(線卡存取開關(guān)) |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| L7558 | 制造商:HAMAMATSU 制造商全稱:Hamamatsu Corporation 功能描述:High-speed, high-power infrared LED for spatial light transmission |
| L7558-01 | 制造商:HAMAMATSU 制造商全稱:Hamamatsu Corporation 功能描述:High-speed, high-power infrared LED for spatial light transmission |
| L755AC | 制造商:MCM 功能描述:AC ADAPTER L755-S5355 制造商:PREMIER FARNELL 功能描述:AC ADAPTER L755-S5355 |
| L755KEYBOARD | 制造商:MCM 功能描述:KEYBOARD L755-S5355 制造商:PREMIER FARNELL 功能描述:KEYBOARD L755-S5355 |
| L7560 | 制造商:HAMAMATSU 制造商全稱:Hamamatsu Corporation 功能描述:High-speed, high output power LED with mini-lens |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。