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PDF SA571 Data sheet ( Hoja de datos )
| Número de pieza | SA571 | |
| Descripción | Compandor | |
| Fabricantes | ON Semiconductor | |
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SA571
Compandor
The SA571 is a versatile low cost dual gain control circuit in which
either channel may be used as a dynamic range compressor or
expandor. Each channel has a full−wave rectifier to detect the average
value of the signal, a linerarized temperature−compensated variable
gain cell, and an operational amplifier.
The SA571 is well suited for use in cellular radio and radio
communications systems, modems, telephone, and satellite
broadcast/receive audio systems.
Features
• Complete Compressor and Expandor in one IChip
• Temperature Compensated
• Greater than 110 dB Dynamic Range
• Operates Down to 6.0 VDC
• System Levels Adjustable with External Components
• Distortion may be Trimmed Out
• Dynamic Noise Reduction Systems
• Voltage Controlled Amplifier
• Pb−Free Packages are Available*
Applications
• Cellular Radio
• High Level Limiter
• Low Level Expandor − Noise Gate
• Dynamic Filters
• CD Player
www.DataSheet4U.com
http://onsemi.com
16
1
SOIC−16 WB
D SUFFIX
CASE 751G
MARKING
DIAGRAMS
16
SA571D
AWLYYWWG
1
16
1
PDIP−16
N SUFFIX
CASE 648
A
WL
YY
WW
G
16
SA571N
AWLYYWWG
1
= Assembly Location
= Wafer Lot
= Year
= Work Week
= Pb−Free Package
PIN CONNECTIONS
D, and N Packages*
RECT CAP 1 1
RECT IN 1 2
DG CELL IN 1 3
GND 4
INV. IN 1 5
RES. R3 1 6
OUTPUT 1 7
THD TRIM 1 8
16 RECT CAP 2
15 RECT IN 2
14 DG CELL IN 2
13 VCC
12 INV. IN 2
11 RES. R3 2
10 OUTPUT 2
9 THD TRIM 2
TOP VIEW
*SOL − Released in Large SO Package Only.
*For additional information on our Pb−Free strategy and soldering details, please
download the ON Semiconductor Soldering and Mounting Techniques
Reference Manual, SOLDERRM/D.
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 9 of this data sheet.
© Semiconductor Components Industries, LLC, 2006
March, 2006 − Rev. 4
1
Publication Order Number:
SA571/D
1 page  
SA571
INTRODUCTION
Much interest has been expressed in high performance
electronic gain control circuits. For non−critical
applications, an integrated circuit operational
transconductance amplifier can be used, but when
high−performance is required, one has to resort to complex
discrete circuitry with many expensive, well−matched
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 signal−to−noise 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 signal−to−noise 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 signal−to−noise ratio of a restricted dynamic
range channel. The input level range of +20 to −80 dB is
shown undergoing a 2−to−1 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 full−wave 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 Hook−up and Operation
Figure 5 shows the block diagram of one half of the chip,
(there are two identical channels on the IC). The full−wave
averaging rectifier provides a gain control current, IG, for the
variable gain (DG) cell. The output of the DG 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 non−inverting 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
+20
0dB
OUTPUT
LEVEL
−20
0dB
−40
NOISE
−80
−40
−80
Figure 4. Restricted Dynamic Range Channel
THD TRIM
R3 INVIN
GIN R2
3,14 20kW
RECTIN R1
8,9
R3
5,12
6,11
20kW
DG
IG
R4
30kW
−
VREF
+
1.8V
OUTPUT
7,10
2,15 10kW
1,16
VCC PIN 13
GND PIN 4
CRECT
Figure 5. Chip Block Diagram (1 of 2 Channels)
http://onsemi.com
5
5 Page 
SA571
ON Semiconductor and
are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice
to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability
arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages.
“Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All
operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights
nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications
intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should Buyer
purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates,
and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death
associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal
Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner.
PUBLICATION ORDERING INFORMATION
LITERATURE FULFILLMENT:
Literature Distribution Center for ON Semiconductor
P.O. Box 61312, Phoenix, Arizona 85082−1312 USA
Phone: 480−829−7710 or 800−344−3860 Toll Free USA/Canada
Fax: 480−829−7709 or 800−344−3867 Toll Free USA/Canada
Email: [email protected]
N. American Technical Support: 800−282−9855 Toll Free
USA/Canada
Japan: ON Semiconductor, Japan Customer Focus Center
2−9−1 Kamimeguro, Meguro−ku, Tokyo, Japan 153−0051
Phone: 81−3−5773−3850
http://onsemi.com
11
ON Semiconductor Website: http://onsemi.com
Order Literature: http://www.onsemi.com/litorder
For additional information, please contact your
local Sales Representative.
SA571/D
11 Page | ||
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| PDF Descargar | [ Datasheet SA571.PDF ] | |
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