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參數(shù)資料
| 型號： | SA571DR2 |
| 廠商： | ON Semiconductor |
| 文件頁數(shù)： | 7/11頁 |
| 文件大小： | 0K |
| 描述： | IC COMPANDOR DUAL GAIN 16-SOIC |
| 產(chǎn)品變化通告： | Product Obsolescence 11/Feb/2009 |
| 標(biāo)準(zhǔn)包裝： | 1,000 |
| 類型： | 壓縮擴(kuò)展器 |
| 應(yīng)用： | 蜂窩式無線電，播放器 |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 16-SOIC（0.295"，7.50mm 寬） |
| 供應(yīng)商設(shè)備封裝： | 16-SOIC W |
| 包裝： | 帶卷 (TR) |
SA571
http://onsemi.com
5
INTRODUCTION
Much interest has been expressed in high performance
electronic
gain
control
circuits.
For
noncritical
applications,
an
integrated
circuit
operational
transconductance amplifier can be used, but when
highperformance is required, one has to resort to complex
discrete circuitry with many expensive, wellmatched
components. This paper describes an inexpensive integrated
circuit, the SA571 Compandor, which offers a pair of high
performance gain control circuits featuring low distortion
(<0.1%), high signaltonoise ratio (90 dB), and wide
dynamic range (110 dB).
Circuit Background
The SA571 Compandor was originally designed to satisfy
the requirements of the telephone system. When several
telephone channels are multiplexed onto a common line, the
resulting signaltonoise ratio is poor and companding is
used to allow a wider dynamic range to be passed through
the channel. Figure 4 graphically shows what a compandor
can do for the signaltonoise ratio of a restricted dynamic
range channel. The input level range of +20 to 80 dB is
shown undergoing a 2to1 compression where a 2.0 dB
input level change is compressed into a 1.0 dB output level
change by the compressor. The original 100 dB of dynamic
range is thus compressed to a 50 dB range for transmission
through
a
restricted
dynamic
range
channel.
A
complementary expansion on the receiving end restores the
original signal levels and reduces the channel noise by as
much as 45 dB.
The significant circuits in a compressor or expander are
the rectifier and the gain control element. The phone system
requires a simple fullwave averaging rectifier with good
accuracy, since the rectifier accuracy determines the (input)
output level tracking accuracy. The gain cell determines the
distortion and noise characteristics, and the phone system
specifications here are very loose. These specs could have
been met with a simple Operational Transconductance
Multiplier, or OTA, but the gain of an OTA is proportional
to temperature and this is very undesirable. Therefore, a
linearized transconductance multiplier was designed which
is insensitive to temperature and offers low noise and low
distortion performance. These features make the circuit
useful in audio and data systems as well as in
telecommunications systems.
Basic Hookup and Operation
Figure 5 shows the block diagram of one half of the chip,
(there are two identical channels on the IC). The fullwave
averaging rectifier provides a gain control current, IG, for the
variable gain (
DG) cell. The output of theDG cell is a current
which is fed to the summing node of the operational
amplifier. Resistors are provided to establish circuit gain and
set the output DC bias.
The circuit is intended for use in single power supply
systems, so the internal summing nodes must be biased at
some voltage above ground. An internal band gap voltage
reference provides a very stable, low noise 1.8 V reference
denoted VREF. The noninverting input of the op amp is tied
to VREF, and the summing nodes of the rectifier and DG cell
(located at the right of R1 and R2) have the same potential.
The THD trim pin is also at the VREF potential.
INPUT
LEVEL
COMPRESSION
EXP
ANSION
OUTPUT
LEVEL
NOISE
+20
0dB
40
80
20
0dB
40
80
Figure 4. Restricted Dynamic Range Channel
VCC PIN 13
GND PIN 4
OUTPUT
7,10
VREF
1.8V
R4
30k
W
1,16
CRECT
R1
10k
W
2,15
RECTIN
GIN
3,14
20k
W
R2
20k
W
R3
6,11
5,12
INVIN
R3
THD TRIM
8,9
IG
DG
Figure 5. Chip Block Diagram (1 of 2 Channels)
+
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SA571DR2G | 功能描述:音頻放大器 Dual Gain Compandor Industrial Temp RoHS:否 制造商:STMicroelectronics 產(chǎn)品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| SA571E-2200 | 制造商:Elan 功能描述:TOUCH PAD |
| SA571FB | 制造商:SIGNET 功能描述: |
| SA571N | 功能描述:音頻放大器 Dual Gain Compandor RoHS:否 制造商:STMicroelectronics 產(chǎn)品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| SA571N,602 | 制造商:NXP Semiconductors 功能描述: |
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