Philips ne572 DATASHEETS

INTEGRATED CIRCUITS

NE/SA572

Programmable analog compandor

Product specification 1987 Oct 7
IC17 Data Handbook

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Philips Semiconductors Product specification

NE/SA572Programmable analog compandor

DESCRIPTION

The NE572 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 buf fer permits independent control of
dynamic attack and recovery time with minimum external
components and improved low frequency gain control ripple
distortion over previous compandors.

The NE572 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.

FEA TURES

•Independent control of attack and recovery time

•Improved low frequency gain control ripple

•Complementary gain compression and expansion with external op

amp

•Wide dynamic range—greater than 110dB

•T emperature-compensated gain control

•Low distortion gain cell

•Low noise—6µV typical

•Wide supply voltage range—6V-22V

•System level adjustable with external components

PIN CONFIGURATION

D1, N, F Packages

TRACK TRIM A

RECOV. CAP A

RECT. IN A

ATTACK CAP A

∆G OUT A

THD TRIM A

NOTE:

1. D package released in large SO (SOL) package only.

1
2
3
4
5
6

∆G IN A

7
8

GND

Figure 1. Pin Configuration

APPLICATIONS

•Dynamic noise reduction system

•Voltage control amplifier

•Stereo expandor

•Automatic level control

•High-level limiter

•Low-level noise gate

•State variable filter

16

V

CC

15

TRACK TRIM B

14

RECOV. CAP B

13

RECT. IN B

12

ATTACK CAP B
∆G OUT B

11
10

THD TRIM B
∆G IN B

9

SR00694

ORDERING INFORMATION

DESCRIPTION TEMPERATURE RANGE ORDER CODE DWG #

16-Pin Plastic Small Outline (SO) 0 to +70°C NE572D SOT109-1
16-Pin Plastic Dual In-Line Package (DIP) 0 to +70°C NE572N SOT38-4
16-Pin Plastic Small Outline (SO) –40 to +85°C SA572D SOT109-1
16-Pin Ceramic Dual In-Line Package (Cerdip) –40 to +85°C SA572F 0582B
16-Pin Plastic Dual In-Line Package (DIP) –40 to +85°C SA572N SOT38-4

ABSOLUTE MAXIMUM RATINGS

SYMBOL PARAMETER RATING UNIT

V

CC

T

A

P

D

Supply voltage 22 V
Operating temperature range

NE572 0 to +70 °C
SA572 –40 to +85

Power dissipation 500 mW

DC

1987 Oct 7 853-0813 90829

2

Philips Semiconductors Product specification

SYMBOL

PARAMETER

TEST CONDITIONS

UNIT

NE/SA572Programmable analog compandor

BLOCK DIAGRAM

(7,9)

(6,10)

(3,13)

(16)

R1

6.8k
∆G

500

Ω

GAIN CELL

–
+

270

Ω

RECTIFIER

P.S.

(8) (4,12) (2,14)

10k

–
+

BUFFER 10k

(5,11)

(1,15)

SR00695

Figure 2. Block Diagram

DC ELECTRICAL CHARACTERISTICS

Standard test conditions (unless otherwise noted) VCC=15V, TA=25°C; Expandor mode (see Test Circuit). Input signals at unity gain level (0dB)
= 100mV

V

CC

I

CC

V

R

THD

THD

THD

PSRR

at 1kHz; V

RMS

1

Supply voltage 6 22 6 22 V
Supply current No signal 6 6.3 mA
Internal voltage reference 2.3 2.5 2.7 2.3 2.5 2.7 V
Total harmonic distortion

(untrimmed)
Total harmonic distortion

(trimmed)
Total harmonic distortion

(trimmed)
No signal output noise

DC level shift (untrimmed)
Unity gain level –1 0 +1 –1.5 0 +1.5 dB

Large–signal distortion V1=V2=400mV 0.7 3.0 0.7 3 %
Tracking error (measured
relative to value at unity Rectifier input
gain)= V2=+6dB V1=0dB ±0.2 ±0.2
[VO–VO (unity gain)]dB V2=–30dB V1=0dB ±0.5 –1.5 ±0.5 –2.5 dB
–V2dB +0.8 +1.6

Channel crosstalk
Power supply rejection ra-

tio

= V2; R

= 3.3kΩ; R

2

= 17.3kΩ.

3

1kHz CA=1.0µF 0.2 1.0 0.2 1.0 %

1kHz CR=10µF 0.05 0.05 %

100Hz 0.25 0.25 %

Input to V1 and V2 grounded

(20–20kHz)

Input change from no signal to

100mV

RMS

200mV

into channel A, measured

RMS

output on channel B

120Hz 70 70 dB

NE572 SA572

Min Typ Max Min Typ Max

DC

DC

6 25 6 25 µV

±20 ±50 ±20 ±50 mV

60 60 dB

1987 Oct 7

3

Philips Semiconductors Product specification

NE/SA572Programmable analog compandor

TEST CIRCUIT

2.2µF

V

1

5Ω

= 10µF

2.2µF

1%

R

2

3.3k (3,13)

V

2

(7,9)

6.8k

(2,14)

(4,12)

∆G

BUFFER

RECTIFIER

(5,11)

(6,10)

(8)

(1,15)

(16)

Figure 3. Test Circuit

AUDIO SIGNAL PROCESSING IC COMBINES VCA
AND FAST ATTACK/SLOW RECOVERY LEVEL
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.

With the introduction of the Signetics NE572 this high-performance
noise reduction concept becomes feasible for consumer hi fi
applications. The NE572 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
amp for current-to-voltage conversion, the VCA features low
distortion, low noise and wide dynamic range.

The novel level sensor which provides gain control current for the
VCA gives lower gain control ripple and independent control of fast
attack, slow recovery dynamic response. An attack capacitor C
with an internal 10k resistor RA defines the attack time tA. The
recovery time t
C

and an internal 10k resistor RR. Typical attack time of 4ms for

R

of a tone burst is defined by a recovery capacitor

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.

A

+

22µF

22µF

100Ω

V

+15V

–15V

0

82k

1k +

2.2k

2.2µF

1%

R

17.3k

270pF

1µF

3

–

NE5234

+

.1µF

+

The NE572 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
NE572 is designed for consumer application over a temperature

range 0-70

The SA572 is intended for applications from –40°C to

+85°C.

NE572 BASIC APPLICATIONS
Description

The NE572 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.

Gain Cell

Figure 4 shows the circuit configuration of the gain cell. Bases of the
differential pairs Q
inputs of OPA A
of Q1-Q2 and the VBE of Q3-Q4 equal. The following relationship can
be derived from the transistor model equation in the forward active
region.

V

BE

Q3Q4

 

(VBE = VT IIN IC/IS)

and Q3-Q4 are both tied to the output and

1-Q2

. The negative feedback through Q1 holds the V

1

BE

Q1Q2

SR00696

BE

1987 Oct 7

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