SA572D-T [NXP]
IC SPECIALTY ANALOG CIRCUIT, PDSO16, Analog IC:Other;
| 型号： | SA572D-T |
| 厂家： | 
NXP |
| 描述： | IC SPECIALTY ANALOG CIRCUIT, PDSO16, Analog IC:Other |
| 文件： | 总12页 (文件大小：139K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
INTEGRATED CIRCUITS
SA572
Programmable analog compandor
Product specification
IC17 Data Handbook
1998 Nov 03
Philips
Semiconductors
Philips Semiconductors
Product specification
Programmable analog compandor
SA572
DESCRIPTION
PIN CONFIGURATION
The SA572 is a dual-channel, high-performance gain control circuit
in which either channel may be used for dynamic range
compression or expansion. Each channel has a full-wave rectifier to
detect the average value of input signal, a linearized,
temperature-compensated variable gain cell (∆G) and a dynamic
time constant buffer. The buffer permits independent control of
dynamic attack and recovery time with minimum external
components and improved low frequency gain control ripple
distortion over previous compandors.
1
D , N, Packages
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
V
TRACK TRIM A
CC
TRACK TRIM B
RECOV. CAP A
RECT. IN A
RECOV. CAP B
RECT. IN B
ATTACK CAP A
∆G OUT A
ATTACK CAP B
∆G OUT B
THD TRIM A
The SA572 is intended for noise reduction in high-performance
audio systems. It can also be used in a wide range of
communication systems and video recording applications.
∆G IN A
THD TRIM B
∆G IN B
GND
NOTE:
1. D package released in large SO (SOL) package only.
FEATURES
SR00694
• Independent control of attack and recovery time
Figure 1. Pin Configuration
• Improved low frequency gain control ripple
• Complementary gain compression and expansion with
external op amp
APPLICATIONS
• Wide dynamic range—greater than 110dB
• Temperature-compensated gain control
• Low distortion gain cell
• Dynamic noise reduction system
• Voltage control amplifier
• Stereo expandor
• Low noise—6µV typical
• Automatic level control
• High-level limiter
• Wide supply voltage range—6V-22V
• System level adjustable with external components
• Low-level noise gate
• State variable filter
ORDERING INFORMATION
DESCRIPTION
TEMPERATURE RANGE
–40 to +85°C
ORDER CODE
SA572D
DWG #
SOT162-1
SOT38-4
16-Pin Plastic Small Outline (SOL)
16-Pin Plastic Dual In-Line Package (DIP)
–40 to +85°C
SA572N
ABSOLUTE MAXIMUM RATINGS
SYMBOL
PARAMETER
RATING
UNIT
V
CC
Supply voltage
22
V
DC
Operating temperature range
SA572
T
A
–40 to +85
500
°C
P
Power dissipation
mW
D
2
1998 Nov 03
853-0813 20294
Philips Semiconductors
Product specification
Programmable analog compandor
SA572
BLOCK DIAGRAM
R1
(5,11)
(7,9)
6.8k
∆G
(6,10)
500
Ω
GAIN CELL
(1,15)
–
+
–
+
(3,13)
10k
BUFFER
10k
270
RECTIFIER
Ω
(16)
P.S.
(8)
(4,12)
(2,14)
SR00695
Figure 2. Block Diagram
DC ELECTRICAL CHARACTERISTICS
Standard test conditions (unless otherwise noted) V =15V, T =25°C; Expandor mode (see Test Circuit).
CC
A
Input signals at unity gain level (0dB) = 100mV
at 1kHz; V = V ; R = 3.3kΩ; R = 17.3kΩ.
1 2 2 3
RMS
SA572
SYMBOL
PARAMETER
TEST CONDITIONS
UNIT
Max
Min
Typ
V
Supply voltage
6
22
6.3
2.7
1.0
V
DC
CC
I
Supply current
No signal
mA
CC
V
R
Internal voltage reference
2.3
2.5
V
DC
THD
THD
THD
Total harmonic distortion (untrimmed)
Total harmonic distortion (trimmed)
Total harmonic distortion (trimmed)
1kHz C =1.0µF
0.2
%
%
%
A
1kHz C =10µF
0.05
0.25
R
100Hz
No signal output noise
DC level shift (untrimmed)
Unity gain level
Input to V and V grounded (20–20kHz)
6
±20
0
25
±50
+1.5
3
µV
mV
dB
%
1
2
Input change from no signal to 100mV
RMS
–1.5
Large-signal distortion
V =V =400mV
0.7
1
2
Rectifier input
V =+6dB V =0dB
Tracking error
(measured relative to value at unity
±0.2
±0.5
dB
dB
2
1
gain)= [V –V (unity gain)]dB –V dB
O
O
2
V =–30dB V =0dB
–2.5, +1.6
2
1
200mV
into channel A,
RMS
Channel crosstalk
60
dB
dB
measured output on channel B
PSRR
Power supply rejection ratio
120Hz
70
3
1998 Nov 03
Philips Semiconductors
Product specification
Programmable analog compandor
SA572
TEST CIRCUIT
100Ω
1µF
–15V
22µF
+
1%
2.2µF
R
3
6.8k
(7,9)
(5,11)
∆G
V
1
17.3k
82k
–
+
5Ω
270pF
(2,14)
(4,12)
NE5234
V
0
2.2k
= 10µF
(6,10)
BUFFER
1k
+
2.2µF
(8)
(1,15)
2.2µF
3.3k (3,13)
+15V
V
RECTIFIER
2
(16)
+
R
2
1%
22µF
.1µF
SR00696
Figure 3. Test Circuit
amp for current-to-voltage conversion, the VCA features low
distortion, low noise and wide dynamic range.
AUDIO SIGNAL PROCESSING IC COMBINES VCA
AND FAST ATTACK/SLOW RECOVERY LEVEL
The novel level sensor which provides gain control current for the
VCA gives lower gain control ripple and independent control of fast
SENSOR
In high-performance audio gain control applications, it is desirable to
independently control the attack and recovery time of the gain
control signal. This is true, for example, in compandor applications
for noise reduction. In high end systems the input signal is usually
split into two or more frequency bands to optimize the dynamic
behavior for each band. This reduces low frequency distortion due
to control signal ripple, phase distortion, high frequency channel
overload and noise modulation. Because of the expense in
hardware, multiple band signal processing up to now was limited to
professional audio applications.
attack, slow recovery dynamic response. An attack capacitor C
A
with an internal 10k resistor R defines the attack time t . The
A
A
recovery time t of a tone burst is defined by a recovery capacitor
R
C
and an internal 10k resistor R . Typical attack time of 4ms for
R
R
the high-frequency spectrum and 40ms for the low frequency band
can be obtained with 0.1µF and 1.0µF attack capacitors,
respectively. Recovery time of 200ms can be obtained with a 4.7µF
recovery capacitor for a 100Hz signal, the third harmonic distortion
is improved by more than 10dB over the simple RC ripple filter with
a single 1.0µF attack and recovery capacitor, while the attack time
remains the same.
With the introduction of the Signetics SA572 this high-performance
noise reduction concept becomes feasible for consumer hi fi
applications. The SA572 is a dual channel gain control IC. Each
channel has a linearized, temperature-compensated gain cell and an
improved level sensor. In conjunction with an external low noise op
The SA572 is assembled in a standard 16-pin dual in-line plastic
package and in oversized SOL package. It operates over a wide
supply range from 6V to 22V. Supply current is less than 6mA. The
SA572 is designed for applications from –40°C to +85°C.
4
1998 Nov 03
Philips Semiconductors
Product specification
Programmable analog compandor
SA572
SA572 BASIC APPLICATIONS
I1 ) IIN
I2 * I1 * IIN
ǒ Ǔ ǒ
Ǔ (2)
VTIn
* VTIn
IS
IS
Description
The SA572 consists of two linearized, temperature-compensated
gain cells (∆G), each with a full-wave rectifier and a buffer amplifier
as shown in the block diagram. The two channels share a 2.5V
common bias reference derived from the power supply but otherwise
operate independently. Because of inherent low distortion, low noise
and the capability to linearize large signals, a wide dynamic range
can be obtained. The buffer amplifiers are provided to permit control
of attack time and recovery time independent of each other.
Partitioned as shown in the block diagram, the IC allows flexibility in
the design of system levels that optimize DC shift, ripple distortion,
tracking accuracy and noise floor for a wide range of application
requirements.
VIN
where IIN
+
R1
R = 6.8kΩ
I = 140µA
1
1
I = 280µA
2
I
O
is the differential output current of the gain cell and I is the gain
G
control current of the gain cell.
If all transistors Q through Q are of the same size, equation (2)
1
4
can be simplified to:
2
I2
1
I2
ǒ
Ǔ
IO
+
@ IIN @ IG
*
I2 * 2I1 @ IG
(3)
Gain Cell
Figure 4 shows the circuit configuration of the gain cell. Bases of the
The first term of Equation 3 shows the multiplier relationship of a
linearized two quadrant transconductance amplifier. The second
term is the gain control feedthrough due to the mismatch of devices.
In the design, this has been minimized by large matched devices
and careful layout. Offset voltage is caused by the device mismatch
and it leads to even harmonic distortion. The offset voltage can be
trimmed out by feeding a current source within ±25µA into the THD
trim pin.
differential pairs Q -Q and Q -Q are both tied to the output and
1
2
3
4
inputs of OPA A . The negative feedback through Q holds the V
1
1
BE
of Q -Q and the V of Q -Q equal. The following relationship can
1
2
BE
3
4
be derived from the transistor model equation in the forward active
region.
DVBE
+ DBE
Q3Q4
Q1Q2
(V = V I IC/IS)
The residual distortion is third harmonic distortion and is caused by
gain control ripple. In a compandor system, available control of fast
attack and slow recovery improve ripple distortion significantly. At
the unity gain level of 100mV, the gain cell gives THD (total harmonic
distortion) of 0.17% typ. Output noise with no input signals is only
BE
T IN
1
2
1
2
1
2
1
2
IG
)
IO
IG
*
IO
V I
* V I
n
T
ǒ Ǔ ǒ Ǔ
n
T
IS
IS
6µV in the audio spectrum (10Hz-20kHz). The output current I
O
must feed the virtual ground input of an operational amplifier with a
resistor from output to inverting input. The non-inverting input of the
VIN
where IIN
+
R1
operational amplifier has to be biased at V
if the output current
REF
R = 6.8kΩ
1
I
O
is DC coupled.
I = 140µA
1
I = 280µA
2
V+
1
2
1
2
I
)
I
G
O
I
1
140µA
A1
I
O
–
+
Q
Q
Q
1
2
Q
3
4
R1
6.8k
I
2
I
G
280µA
V
REF
THD
TRIM
V
IN
SR00697
Figure 4. Basic Gain Cell Schematic
5
1998 Nov 03
Philips Semiconductors
Product specification
Programmable analog compandor
SA572
Rectifier
Buffer Amplifier
The rectifier is a full-wave design as shown in Figure 5. The input
In audio systems, it is desirable to have fast attack time and slow
recovery time for a tone burst input. The fast attack time reduces
transient channel overload but also causes low-frequency ripple
distortion. The low-frequency ripple distortion can be improved with
the slow recovery time. If different attack times are implemented in
corresponding frequency spectrums in a split band audio system,
high quality performance can be achieved. The buffer amplifier is
designed to make this feature available with minimum external
components. Referring to Figure 6, the rectifier output current is
voltage is converted to current through the input resistor R and
turns on either Q or Q depending on the signal polarity. Deadband
of the voltage to current converter is reduced by the loop gain of the
gain block A . If AC coupling is used, the rectifier error comes only
from input bias current of gain block A . The input bias current is
2
5
6
2
2
typically about 70nA. Frequency response of the gain block A also
causes second-order error at high frequency. The collector current
2
of Q is mirrored and summed at the collector of Q to form the full
6
5
wave rectified output current I . The rectifier transfer function is
mirrored into the input and output of the unipolar buffer amplifier A
3
R
through Q , Q and Q . Diodes D and D improve tracking
8
9
10
11
12
VIN * VREF
(4)
accuracy and provide common-mode bias for A . For a
3
IR
+
R2
positive-going input signal, the buffer amplifier acts like a
voltage-follower. Therefore, the output impedance of A makes the
3
If V is AC-coupled, then the equation will be reduced to:
IN
contribution of capacitor CR to attack time insignificant. Neglecting
diode impedance, the gain Ga(t) for ∆G can be expressed as
follows:
VIN(AVG)
IRAC
+
R2
*t
The internal bias scheme limits the maximum output current I to be
around 300µA. Within a ±1dB error band the input range of the rectifier
is about 52dB.
R
t
Ga(t) + (GaINT * GaFNL
Ga =Initial Gain
e
) GaFNL
A
INT
Ga
=Final Gain
FNL
V
* V
IN
REF
V+
I
+
R
τ =R • CA=10k • CA
A A
R
2
where τ is the attack time constant and R is a 10k internal
A
A
resistor. Diode D opens the feedback loop of A for a
15
3
negative-going signal if the value of capacitor CR is larger than
capacitor CA. The recovery time depends only on CR • R . If the
R
diode impedance is assumed negligible, the dynamic gain G (t) for
∆G is expressed as follows.
R
+
–
V
REF
A2
*t
Q5
t
GR(t) + (GRINT * GRFNL
e
) G
R
RFNL
G (t)=(G –G ) e +G
R
R INT
R FNL
R FNL
τR=R • CR=10k • CR
R
D7
where τR is the recovery time constant and R is a 10k internal
R
resistor. The gain control current is mirrored to the gain cell through
Q6
Q
. The low level gain errors due to input bias current of A and A
2 3
14
R2
can be trimmed through the tracking trim pin into A with a current
source of ±3µA.
3
V
IN
SR00698
Figure 5. Simplified Rectifier Schematic
6
1998 Nov 03
Philips Semiconductors
Product specification
Programmable analog compandor
SA572
V+
Q8
Q9
Q10
I
= 2I
R2
Q
Q17
I
R2
X2
Q16
10k
V
IN
I
+
R
R
–
+
D15
D13
A3
10k
I
R1
X2
Q18
Q14
D11
D12
CR
CA
TRACKING
TRIM
SR00699
Figure 6. Buffer Amplifier Schematic
error. However, an impedance buffer A may be necessary if the
input is voltage drive with large source impedance.
Basic Expandor
Figure 7 shows an application of the circuit as a simple expandor.
The gain expression of the system is given by
1
The gain cell output current feeds the summing node of the external
OPA A . R and A convert the gain cell output current to the output
2
3
2
R3 @ VIN(AVG)
R2 @ R1
VOUT
VIN
2
I1
(5)
voltage. In high-performance applications, A has to be low-noise,
+
@
2
high-speed and wide band so that the high-performance output of
the gain cell will not be degraded. The non-inverting input of A can
2
(I =140µA)
1
be biased at the low noise internal reference Pin 6 or 10. Resistor
R is used to bias up the output DC level of A for maximum swing.
Both the resistors R and R are tied to internal summing nodes. R
1
1
2
4
2
is a 6.8k internal resistor. The maximum input current into the gain
The output DC level of A is given by
2
cell can be as large as 140µA. This corresponds to a voltage level of
140µA • 6.8k=952mV peak. The input peak current into the rectifier
is limited to 300µA by the internal bias system. Note that the value
R3
ǒ1 ) Ǔ
R4
R3
(6)
VODC + VREF
* VB
R4
of R can be increased to accommodate higher input level. R and
1
2
V
B
can be tied to a regulated power supply for a dual supply system
R are external resistors. It is easy to adjust the ratio of R /R for
3
3
2
and be grounded for a single supply system. CA sets the attack time
constant and CR sets the recovery time constant. *5COL
desirable system voltage and current levels. A small R results in
higher gain control current and smaller static and dynamic tracking
2
7
1998 Nov 03
Philips Semiconductors
Product specification
Programmable analog compandor
SA572
R4
R3
+VB
17.3k
–
C
IN2
R1
(5,11)
A1
∆
G
C
IN1
(7,9)
6.8k
V
V
+
IN
A2
OUT
(6,10) R6
2.2µF
V
REF
1k
(2,14)
C1
R5
100k
(4,12)
BUFFER
2.2µF
C
2.2µF
IN3
R2
3.3k
CA CR
1µF 10µF
(3,13)
(8)
(16)
+V
CC
SR00700
Figure 7. Basic Expandor Schematic
Basic Compressor
R4
RDC1
9.1k
RDC2
9.1k
Figure 8 shows the hook-up of the circuit as a compressor. The IC is
put in the feedback loop of the OPA A . The system gain expression
1
CDC
is as follows:
10µF
C2
.1µF
1
2
VOUT
VIN
I1
2
R2 @ R1
C
IN1
2.2µF
(7)
+
ǒ
@
Ǔ
D1
D2
V
R3 @ VIN(AVG)
IN
–
+
V
OUT
R3
17.3k
A1
R
, R
, and CDC form a DC feedback for A . The output DC
DC2 1
DC1
level of A is given by
1
C1
RDC1 ) RDC2
1k R5
(6,10)
(8)
ǒ1 )
Ǔ
VODC + VREF
R4
V
REF
RDC1 ) RDC2
R1
6.8k
(7,9)
@ ǒ
Ǔ
* VB
∆
G
R4
C
2.2µF
IN2
The zener diodes D and D are used for channel overload
1
2
(5,11)
protection.
(2,14)
(4,12)
C
2.2µF
BUFFER
IN3
3.3k
R2
CR
10µF
CA
1µF
(3,13)
(8)
(16)
V
CC
SR00701
Figure 8. Basic Compressor Schematic
8
1998 Nov 03
Philips Semiconductors
Product specification
Programmable analog compandor
SA572
bandlimiting, band splitting, pre-emphasis, de-emphasis and
Basic Compandor System
equalization are easy to incorporate. The IC is a versatile functional
block to achieve a high performance audio system. Figure 9 shows
the system level diagram for reference.
The above basic compressor and expandor can be applied to
systems such as tape/disc noise reduction, digital audio, bucket
brigade delay lines. Additional system design techniques such as
1
2
2
REL LEVEL ABS LEVEL
V
RMS
COMPRESSION
IN
EXPANDOR
OUT
dB
dBM
INPUT TO ∆G
AND RECT
3.0V
+29.54
+11.76
547.6MV
400MV
+14.77
+12.0
–3.00
–5.78
100MV
10MV
1MV
0.0
–17.78
–37.78
–20
–40
–60
–57.78
–77.78
100µV
10µV
–80
–97.78
SR00702
Figure 9. SA572 System Level
9
1998 Nov 03
Philips Semiconductors
Product specification
Programmable analog compandor
SA572
SO16: plastic small outline package; 16 leads; body width 7.5 mm
SOT162-1
10
1998 Nov 03
Philips Semiconductors
Product specification
Programmable analog compandor
SA572
DIP16: plastic dual in-line package; 16 leads (300 mil)
SOT38-4
11
1998 Nov 03
Philips Semiconductors
Product specification
Programmable analog compandor
SA572
Data sheet status
[1]
Data sheet
status
Product
status
Definition
Objective
specification
Development
This data sheet contains the design target or goal specifications for product development.
Specification may change in any manner without notice.
Preliminary
specification
Qualification
This data sheet contains preliminary data, and supplementary data will be published at a later date.
Philips Semiconductors reserves the right to make chages at any time without notice in order to
improve design and supply the best possible product.
Product
specification
Production
This data sheet contains final specifications. Philips Semiconductors reserves the right to make
changes at any time without notice in order to improve design and supply the best possible product.
[1] Please consult the most recently issued datasheet before initiating or completing a design.
Definitions
Short-form specification — The data in a short-form specification is extracted from a full data sheet with the same type number and title. For
detailed information see the relevant data sheet or data handbook.
Limiting values definition — Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 134). Stress above one
or more of the limiting values may cause permanent damage to the device. These are stress ratings only and operation of the device at these or
at any other conditions above those given in the Characteristics sections of the specification is not implied. Exposure to limiting values for extended
periods may affect device reliability.
Application information — Applications that are described herein for any of these products are for illustrative purposes only. Philips
Semiconductors make no representation or warranty that such applications will be suitable for the specified use without further testing or
modification.
Disclaimers
Life support — These products are not designed for use in life support appliances, devices or systems where malfunction of these products can
reasonably be expected to result in personal injury. Philips Semiconductors customers using or selling these products for use in such applications
do so at their own risk and agree to fully indemnify Philips Semiconductors for any damages resulting from such application.
Righttomakechanges—PhilipsSemiconductorsreservestherighttomakechanges, withoutnotice, intheproducts, includingcircuits,standard
cells, and/or software, described or contained herein in order to improve design and/or performance. Philips Semiconductors assumes no
responsibility or liability for the use of any of these products, conveys no license or title under any patent, copyright, or mask work right to these
products, and makes no representations or warranties that these products are free from patent, copyright, or mask work right infringement, unless
otherwise specified.
Philips Semiconductors
811 East Arques Avenue
P.O. Box 3409
Copyright Philips Electronics North America Corporation 1998
All rights reserved. Printed in U.S.A.
Sunnyvale, California 94088–3409
Telephone 800-234-7381
Date of release: 11-98
Document order number:
9397 750 04749
Philips
Semiconductors
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