- 您现在的位置：买卖IC网 > PDF目录180046 > LUCL9219GAR-DT Low-Cost Line Interface with Reverse Battery and Dual Current Limit PDF资料下载
参数资料
| 型号： | LUCL9219GAR-DT |
| 英文描述： | Low-Cost Line Interface with Reverse Battery and Dual Current Limit |
| 中文描述： | 低成本线接口，具有反向电池和双电流限制 |
| 文件页数： | 15/30页 |
| 文件大小： | 397K |
| 代理商： | LUCL9219GAR-DT |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页当前第15页第16页第17页第18页第19页第20页第21页第22页第23页第24页第25页第26页第27页第28页第29页第30页
22
Agere Systems Inc.
Data Sheet
November 2001
with Reverse Battery and Dual Current Limit
L9219A/G Low-Cost Line Interface
Applications (continued)
ac Design
Codec Types
At this point in the design, the codec needs to be
selected. The interface network between the SLIC and
codec can then be designed. 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.
Below is a brief codec feature summary.
First-Generation Codecs. These perform the basic
filtering, A/D (transmit), D/A (receive), and
-law/A-law
companding. They all have an op amp in front of the
A/D converter for transmit gain setting and hybrid bal-
ance (cancellation at the summing node). Depending
on the type, some have differential analog input stages,
differential analog output stages, 5 V only or
±5 V oper-
ation, and
-law/A-law selectability. These are avail-
able in single and quad designs. This type of codec
requires continuous time analog filtering via external
resistor/capacitor networks to set the ac design param-
eters. An example of this type of codec is the Agere
T7504 quad 5 V only codec.
This type of codec tends to be the most economical in
terms of piece part price, but tends to require more
external components than a third-generation codec.
Furthermore, ac parameters are fixed by the external
R/C network, so software control of ac parameters is
difficult.
Third-Generation Codecs. This class of devices
includes all ac parameters set digitally under micropro-
cessor control. Depending on the device, it may or may
not have data control latches. Additional functionality
sometimes offered includes tone plant generation and
reception, TTX generation, test algorithms, and echo
cancellation. Again, this type of codec may be 5 V only
or
±5 V operation, single quad or 16-channel, and
-law/A-law or 16-bit linear coding selectable. Exam-
ples of this type of codec are the Agere T8535/6 (5 V
only, quad, standard features), T8533/4 (5 V only, quad
with echo cancellation), and the T8531/36 (5 V only
16-channel with self-test).
ac Interface Network
The ac interface network between the L9219 and the
codec will vary depending on the codec selected. With
a first-generation codec, the interface between the
L9219 and codec actually sets the ac parameters. With
a third-generation codec, all ac parameters are set dig-
itally, internal to the codec; thus, the interface between
the L9219 and this type of codec is designed to avoid
overload at the codec input in the transmit direction,
and to optimize signal-to-noise ratio (S/N) in the
receive direction.
Receive Interface
Because the design requirements are very different
with a first- or third-generation codec, the L9219 is
offered with two different receive gains. Each receive
gain was chosen to optimize, in terms of external com-
ponents required, the ac interface between the L9219
and codec.
With a first-generation codec, the termination imped-
ance is set by providing gain shaping through a feed-
back network from the SLIC VITR output to the SLIC
RCVN/RCVP inputs. The L9219 provides a transcon-
ductance from T/R to VITR in the transmit direction and
a single ended to differential gain in the receive direc-
tion from either RCVN or RCVP to T/R. Assuming a
short from VITR to RCVN or RCVP, the maximum
impedance that is seen looking into the SLIC is the
product of the SLIC transconductance times the SLIC
receive gain, plus the protection resistors. The various
specified termination impedance can range over the
voice band as low as 300
up to over 1000 . Thus, if
the SLIC gains are too low, it will be impossible to syn-
thesize the higher termination impedances. Further-
more, the termination that is achieved will be far less
than what is calculated by assuming a short for SLIC
output to SLIC input. In the receive direction, in order to
control echo, the gain is typically a loss, which requires
a loss network at the SLIC RCVN/RCVP inputs, which
will reduce the amount of gain that is available for ter-
mination impedance. For this reason a high-gain SLIC
is required with a first-generation codec.
相关PDF资料 |
PDF描述 |
|---|---|
| LUPXA255A0C200 | 32-BIT, 200 MHz, MICROPROCESSOR, PBGA256 |
| LUPXA255A0C300 | 32-BIT, 300 MHz, MICROPROCESSOR, PBGA256 |
| LV100 | Voltage Transducer LV 100 |
| LV200-AW | Voltage Transducer LV 200-AW/2 |
| LV25-1000 | Voltage Transducer LV 25-1000 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LUCL9310AP-D | 制造商:AGERE 制造商全称:AGERE 功能描述:Line Interface and Line Access Circuit Full-Feature SLIC,Ringing Relay,and Test Access Device |
| LUCL9310AP-DT | 制造商:AGERE 制造商全称:AGERE 功能描述:Line Interface and Line Access Circuit Full-Feature SLIC,Ringing Relay,and Test Access Device |
| LUCL9310GP-D | 制造商:AGERE 制造商全称:AGERE 功能描述:Line Interface and Line Access Circuit Full-Feature SLIC,Ringing Relay,and Test Access Device |
| LUCL9310GP-DT | 制造商:AGERE 制造商全称:AGERE 功能描述:Line Interface and Line Access Circuit Full-Feature SLIC,Ringing Relay,and Test Access Device |
| LUCL9311AP-D | 制造商:AGERE 制造商全称:AGERE 功能描述:Line Interface and Line Access Circuit Full-Feature SLIC with High Longitudinal Balance, Ringing Relay,and GR-909 Test Access |
发布紧急采购，3分钟左右您将得到回复。