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RF COMMUNICATIONS PRODUCTS
SA575 Low voltage compandor
Product specification Replaces data of 1997 June 28 IC17 1997 Nov 07
Philips Semiconductors
Philips Semiconductors
Product specification
Low voltage compandor
SA575
DESCRIPTION
The SA575 is a precision dual gain control circuit designed for low voltage applications. The SA575's channel 1 is an expandor, while channel 2 can be configured either for expandor, compressor, or automatic level controller (ALC) application.
PIN CONFIGURATION
D1 and DK Packages
+VIN1 -VIN1 1 2 3 4 20 VCC 19 +VIN2 18 -VIN2 17 VOUT2 16 RECT.IN2 15 CRECT2 14 SUM OUT2 13 COMP.IN2 12 SUM NODE 2 11 GAIN CELL IN2
FEATURES
VOUT
* Operating voltage range from 3V to 7V * Reference voltage of 100mVRMS = 0dB * One dedicated summing op amp per channel and two extra
uncommitted op amps
1 RECT. IN1
CRECT1 5 SUM OUT 1 COMP. IN1 VREF GAIN CELL IN1 6 7 8 9
* 600 drive capability * Single or split supply operation * Wide input/output swing capability * 3000V ESD protection
APPLICATIONS
GND 10 NOTE: 1. Available in large SOL package only.
SR00703
Figure 1. Pin Configuration
* Portable communications * Cellular radio * Cordless telephone * Consumer audio
* Portable broadcast mixers * Wireless microphones * Modems * Electric organs * Hearing aids
ORDERING INFORMATION
DESCRIPTION 20-Pin Plastic Small Outline Large 20-Pin Plastic Shrink Small Outline Package (SSOP) TEMPERATURE RANGE -40 to +85C -40 to +85C ORDER CODE SA575D SA575DK DWG SOT163-1 SOT266-1
ABSOLUTE MAXIMUM RATINGS
RATING SYMBOL VCC VIN TA TSTG JA Single supply voltage Voltage applied to any other pin Operating ambient temperature range Storage temperature range Thermal impedance SOL SSOP PARAMETER SA575 -0.3 to 8 -0.3 to (VCC+0.3) -40 to +85 -65 to +150 112 117 UNITS V V C C C/W C/W
1997 Nov 07
2
853-1665 18666
Philips Semiconductors
Product specification
Low voltage compandor
SA575
BLOCK DIAGRAM and TEST CIRCUIT
0.1F VCC +5V C15
1 2
C3 VOUT
+ -
OP AMP
575
VCC
20 19 18 17
R13 10k
10F
GND VIN
+
OP AMP
+
C14
VREF
+
10F
3 4
3.8k
-
C11
+
5
CRECT 2.2F 3.8k
16
10k VREF G 10k G GND 10k
+
4.7F
CRECT
6 7 8
15 14 13 12 11
+
+
C10 VOUT
GND C6 VIN VREF 10F
2.2F
10F
+
10k
R8 30k R7 30k C8
+
10F
9 10
+
1F
GND
GND
GND
SR00704
Figure 2. Block Diagram and Test Circuit
DC ELECTRICAL CHARACTERISTICS
Typical values are at TA = 25C. Minimum and Maximum values are for the full operating temperature range: -40 to +85C for SA575, except SSOP package is tested at +25C only. VCC = 5V, unless otherwise stated. Both channels are tested in the Expandor mode (see Test Circuit) LIMITS SYMBOL PARAMETER TEST CONDITIONS MIN For compandor, including summing amplifier VCC ICC VREF RL THD ENO 0dB VOS Supply voltage1 Supply current Reference voltage2 Summing amp output load Total harmonic distortion Output voltage noise Unity gain level Output voltage offset Output DC shift 1kHz, 0dB BW = 3.5kHz BW = 20kHz, RS = 0 1kHz No signal No signal to 0dB Gain cell input = 0dB, 1kHz Rectifier input = 6dB, 1kHz Tracking error relative to 0dB Gain cell input = 0dB, 1kHz Rectifier input = -30dB, 1kHz -1.5 -150 -100 -1.0 -1.0 No signal VCC = 5V 3 3 2.4 10 0.12 6 1.5 30 1.5 150 100 1.0 1.0 5 4.2 2.5 7 5.5 2.6 V mA V k % V dB mV mV dB dB SA575 TYP MAX UNITS
1997 Nov 07
3
Philips Semiconductors
Product specification
Low voltage compandor
SA575
DC ELECTRICAL CHARACTERISTICS
SYMBOL Crosstalk For operational amplifier VO RL CMR CMRR IB VOS AVOL SR GBW ENI PSRR Output swing Output load Input common-mode range Common-mode rejection ratio Input bias current Input offset voltage Open-loop gain Slew rate Bandwidth Input voltage noise Power supply rejection ratio PARAMETER
(cont.) LIMITS TEST CONDITIONS MIN 1kHz, 0dB, CREF = 220F RL = 10k 1kHz VCC-0.4 600 0 60 VIN = 0.5V to 4.5V RL = 10k Unity gain Unity gain BW = 20kHz 1kHz, 250mV -1 3 80 1 3 2.5 60 80 1 VCC SA575 TYP -80 VCC MAX -65 dB V V dB A mV dB V/s MHz V dB UNITS
NOTES: 1. Operation down to VCC = 2V is possible, but performance is reduced. See curves in Figure 7a and 7b. 2. Reference voltage, VREF, is typically at 1/2VCC.
FUNCTIONAL DESCRIPTION
This section describes the basic subsystems and applications of the SA575 Compandor. More theory of operation on compandors can be found in AN174 and AN176. The typical applications of the SA575 low voltage compandor in an Expandor (1:2), Compressor (2:1) and Automatic Level Control (ALC) function are explained. These three circuit configurations are shown in Figures 3, 4, 5 respectively. The SA575 has two channels for a complete companding system. The left channel, A, can be configured as a 1:2 Expandor while the right channel, B, can be configured as either a 2:1 Compressor, a 1:2 Expandor or an ALC. Each channel consists of the basic companding building blocks of rectifier cell, variable gain cell, summing amplifier and VREF cell. In addition, the SA575 has two additional high performance uncommitted op amps which can be utilized for application such as filtering, pre-emphasis/de-emphasis or buffering. Figure 6 shows the complete schematic for the applications demo board. Channel A is configured as an expandor while channel B is configured so that it can be used either as a compressor or as an ALC circuit. The switch, S1, toggles the circuit between compressor and ALC mode. Jumpers J1 and J2 can be used to either include the additional op amps for signal conditioning or exclude them from the signal path. Bread boarding space is provided for R1, R2, C1, C2, R10, R11, C10 and C11 so that the response can be tailored for each individual need. The components as specified are suitable for the complete audio spectrum from 20Hz to 20kHz. The most common configuration is as a unity gain non-inverting buffer where R1, C1, C2, R10, C10 and C11 are eliminated and R2 and R11 are shorted. Capacitors C3, C5, C8, and C12 are for DC blocking. In systems where the inputs and outputs are AC coupled, these capacitors and resistors can be eliminated. Capacitors C4 and C9 are for setting the attack and release time constant. C6 is for decoupling and stabilizing the voltage reference circuit. The value of C6 should be such that it will offer a very low impedance to the lowest frequencies of interest. Too small a capacitor will allow supply ripple to modulate the audio path. The 1997 Nov 07 4
better filtered the power supply, the smaller this capacitor can be. R12 provides DC reference voltage to the amplifier of channel B. R6 and R7 provide a DC feedback path for the summing amp of channel B, while C7 is a short-circuit to ground for signals. C14 and C15 are for power supply decoupling. C14 can also be eliminated if the power supply is well regulated with very low noise and ripple.
DEMONSTRATED PERFORMANCE
The applications demo board was built and tested for a frequency range of 20Hz to 20kHz with the component values as shown in Figure 6 and VCC = 5V. In the expandor mode, the typical input dynamic range was from -34dB to +12dB where 0dB is equal to 100mVRMS. The typical unity gain level measured at 0dB @ 1kHz input was +0.5dB and the typical tracking error was +0.1dB for input range of -30 to +10dB. In the compressor mode, the typical input dynamic range was from -42dB to +18dB with a tracking error +0.1dB and the typical unity gain level was +0.5dB. In the ALC mode, the typical input dynamic range was from -42dB to +8dB with typical output deviation of +0.2dB about the nominal output of 0dB. For input greater than +9dB in ALC configuration, the summing amplifier sometimes exhibits high frequency oscillations. There are several solutions to this problem. The first is to lower the values of R6 and R7 to 20k each. The second is to add a current limiting resistor in series with C12 at Pin 13. The third is to add a compensating capacitor of about 22 to 30pF between the input and output of summing amplifier (Pins 12 and 14). With any one of the above recommendations, the typical ALC mode input range increased to +18dB yielding a dynamic range of over 60dB.
EXPANDOR
The typical expandor configuration is shown in Figure 3. The variable gain cell and the rectifier cell are in the signal input path. The VREF is always 1/2 VCC to provide the maximum headroom without clipping. The 0dB ref is 100mVRMS. The input is AC coupled through C5, and the output is AC coupled through C3. If in a system the inputs and outputs are AC coupled, then C3 and C5 can be eliminated, thus requiring only one external component, C4. The variable gain cell and rectifier cell are DC coupled so any offset
Philips Semiconductors
Product specification
Low voltage compandor
SA575
voltage between Pins 4 and 9 will cause small offset error current in the rectifier cell. This will affect the accuracy of the gain cell. This can be improved by using an extra capacitor from the input to Pin 4 and eliminating the DC connection between Pins 4 and 9. The expandor gain expression and the attack and release time constant is given by Equation 1 and Equation 2, respectively. Equation 1. Expandor gain = 4VIN(avg) 3.8k x 100A
Equation 3. 3.8k x 100A 4VIN(avg) where VIN(avg) = 0.95VIN(RMS) Equation 4. R = A = 10k x CRECT = 10k x C4
1/2
Compressor gain =
AUTOMATIC LEVEL CONTROL
Equation 2. The typical Automatic Level Control circuit configuration is shown in Figure 5. It can be seen that it is quite similar to the compressor schematic except that the input to the rectifier cell is from the input path and not from the feedback path. The input is AC coupled through C12 and C13 and the output is AC coupled through C8. Once again, as in the previous cases, if the system input and output signals are already AC coupled, then C12, C13 and C8 could be eliminated. Concerning the compressor, removing R6, R7 and C7 will cause motor-boating in absence of signals. CCOMP is necessary to stabilize the summing amplifier at higher input levels. This circuit provides an input dynamic range greater than 60dB with the output within +0.5dB typical. The necessary design expressions are given by Equation 5 and Equation 6, respectively. Equation 5. 3.8k x 100A ALC gain = 4VIN(avg) Equation 6.
where VIN(avg) = 0.95VIN(RMS) R = A = 10k x CRECT = 10k x C4
COMPRESSOR
The typical compressor configuration is shown in Figure 4. In this mode, the rectifier cell and variable gain cell are in the feedback path. R6 and R7 provide the DC feedback to the summing amplifier. The input is AC coupled through C12 and output is AC coupled through C8. In a system with inputs and outputs AC coupled, C8 and C12 could be eliminated and only R6, R7, C7, and C13 would be required. If the external components R6, R7 and C7 are eliminated, then the output of the summing amplifier will motor-boat in absence of signals or at extremely low signals. This is because there is no DC feedback path from the output to input. In the presence of an AC signal this phenomenon is not observed and the circuit will appear to function properly. The compressor gain expression and the attack and release time constant is given by Equation 3 and Equation 4, respectively.
R = A = 10k x CRECT = 10k x C9
7 C5 EXP IN 10F 10k 9 G 10k 6 C3 EXP OUT 10F
4 3.8k 5 2.2F VREF 8
C4
SR00705
Figure 3. Typical Expandor Configuration
1997 Nov 07
5
Philips Semiconductors
Product specification
Low voltage compandor
SA575
R6 30k C7 VREF 8 12 1F
R7 30k
C12 COMP IN 10F
13 10k
14
C8 COMP OUT 10F
G 10k
11
16 3.8k 15 C9 2.2F
C13 4.7F
SR00706
Figure 4. Typical Compressor Configuration
R6 30k C7 1F
R7 30k
C COMP
VREF 8 12
22pF
C12 ALC IN 10F
13 10k
14
C8 ALC OUT 10F
G 10k
11
C13 4.7F
16 3.8k 16 C9 2.2F
SR00707
Figure 5. Typical ALC Configuration
1997 Nov 07
6
Philips Semiconductors
Product specification
Low voltage compandor
SA575
VCC -5V C15 0.1F C14 VREF
1
R1 C1 C2 R2
+ -
OP AMP
575
VCC
20 19
47F
R12 10k
C12 10F
2 3
+
OP AMP
COMP/ ALC IN
R10
-
18 17
C3 EXP OUT 10F J1
R11
C10 C11 J2
4
3.8k
C13 3.8k
5
2.2F C4
16
C9
ALC S1 COMP
4.7F
6
C5 EXP IN 10F
15
2.2F
7
10k
14
C8
8 VREF
C6 10F
VREF 10k G 10k G GND 10k
13 12 11
R6 30k
R7 30k
10F
COMP/ ALC OUT
9 10
C7 1F
SR00708
Figure 6. SA575 Low Voltage Expandor/Compressor/ALC Demo Board
1997 Nov 07
7
Philips Semiconductors
Product specification
Low voltage compandor
SA575
1.0 0.9 0.8 0.7 0.6 0.5 UNITY GAIN ERROR (dB) 0.4 0.3 0.2 0.1 0.0 -0.1 -0.2 -0.3 -0.4 -0.5 -0.6 -0.7 -0.8 -0.9 -1.0 -50 -25 0 25 TEMPERATURE (C) 50 75 100 VCC 2V VCC 3V VCC 5V VCC 7V
a. Unity Gain Error vs Temperature and VCC
4.4
4.2
4.0 VCC 7V 3.8
I (mA) CC
3.6
VCC 5V
3.4
VCC 3V VCC 2V
3.2
3.0 -50
-25
0
25 TEMPERATURE (C)
50
75
100
b. ICC vs Temperature and VCC Figure 7. Temperature and VCC Curves
SR00709
1997 Nov 07
8
Philips Semiconductors
Product specification
Low voltage compandor
SA575
TYPICAL PERFORMANCE CHARACTERISTICS
GENERAL DIAGRAM 8 10F 4.7F
6
10dB IN
INPUT (20-20kHz)
G
REC SUM OUTPUT
4
2 0dB IN 0 VCC = 5V
-2
OUTPUT LEVEL (dB)
-4
-6
-8
-10
-12
-14
-16
-18 -40dB IN -20
-22 10 100 1000 10000 30000
FREQUENCY (Hz) Figure 8. Compressor Output Frequency Response
SR00710
1997 Nov 07
9
Philips Semiconductors
Product specification
Low voltage compandor
SA575
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
8 INPUT (20-20kHz) 2.5dB IN 4.7F 4 REC OUTPUT SUM 2 0dB IN 0 10F VCC = 5V G GENERAL DIAGRAM
6
-2
OUTPUT LEVEL (dB)
-4
-6
-8
-10
-12
-14
-16
-18 -10dB IN -20
-22 10 100 1000 10000 30000
FREQUENCY (Hz) Figure 9. Expandor Output Frequency Response
SR00711
1997 Nov 07
10
Philips Semiconductors
Product specification
Low voltage compandor
SA575
COMPRESSOR IN +10dB +5dB
EXPANDOR OUT +10dB
100mV 0dB
0dB
100mV 0dB
-5dB
-10dB
-10dB
-10dB
-15dB
-20dB
-20dB
-20dB
-25dB
-30dB
-30dB
-40dB
-40dB
-50dB
-50dB
COMPRESSION
}
1997 Nov 07 11
Figure 10. The Companding Function
}
EXPANSION
SR00712
Philips Semiconductors
Product specification
Low voltage compandor
SA575
SO20: plastic small outline package; 20 leads; body width 7.5 mm
SOT163-1
1997 Nov 07
12
Philips Semiconductors
Product specification
Low voltage compandor
SA575
SSOP20: plastic shrink small outline package; 20 leads; body width 4.4 mm
SOT266-1
1997 Nov 07
13
Philips Semiconductors
Product specification
Low voltage compandor
SA575
DEFINITIONS
Data Sheet Identification
Objective Specification
Product Status
Formative or in Design
Definition
This data sheet contains the design target or goal specifications for product development. Specifications may change in any manner without notice. This data sheet contains preliminary data, and supplementary data will be published at a later date. Philips Semiconductors reserves the right to make changes at any time without notice in order to improve design and supply the best possible product. 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.
Preliminary Specification
Preproduction Product
Product Specification
Full Production
Philips Semiconductors and Philips Electronics North America Corporation reserve the right to make changes, without notice, in the products, including circuits, 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. Applications that are described herein for any of these products are for illustrative purposes only. Philips Semiconductors makes no representation or warranty that such applications will be suitable for the specified use without further testing or modification. LIFE SUPPORT APPLICATIONS Philips Semiconductors and Philips Electronics North America Corporation Products are not designed for use in life support appliances, devices, or systems where malfunction of a Philips Semiconductors and Philips Electronics North America Corporation Product can reasonably be expected to result in a personal injury. Philips Semiconductors and Philips Electronics North America Corporation customers using or selling Philips Semiconductors and Philips Electronics North America Corporation Products for use in such applications do so at their own risk and agree to fully indemnify Philips Semiconductors and Philips Electronics North America Corporation for any damages resulting from such improper use or sale. Philips Semiconductors 811 East Arques Avenue P.O. Box 3409 Sunnyvale, California 94088-3409 Telephone 800-234-7381 (c) Copyright Philips Electronics North America Corporation 1997 All rights reserved. Printed in U.S.A.
Philips Semiconductors
1997 Nov 07 14

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