RF COMMUNICATIONS PRODUCTS SA575 Low voltage compandor Product specification Replaces data of 1997 June 28 IC17 Philips Semiconductors 1997 Nov 07 Philips Semiconductors Product specification Low voltage compandor SA575 DESCRIPTION PIN CONFIGURATION 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. D1 and DK Packages FEATURES • 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 • 600Ω drive capability • Single or split supply operation • Wide input/output swing capability • 3000V ESD protection +VIN1 1 20 VCC -VIN1 2 19 +VIN2 VOUT 3 18 -VIN2 1 RECT. IN1 4 17 VOUT2 CRECT1 5 16 RECT.IN2 SUM OUT 1 6 15 CRECT2 COMP. IN1 7 14 SUM OUT2 VREF 8 13 COMP.IN2 GAIN CELL IN1 9 12 SUM NODE 2 GND 10 11 GAIN CELL IN2 NOTE: 1. Available in large SOL package only. SR00703 Figure 1. Pin Configuration APPLICATIONS • Portable broadcast mixers • Wireless microphones • Modems • Electric organs • Hearing aids • Portable communications • Cellular radio • Cordless telephone • Consumer audio ORDERING INFORMATION TEMPERATURE RANGE ORDER CODE DWG 20-Pin Plastic Small Outline Large DESCRIPTION -40 to +85°C SA575D SOT163-1 20-Pin Plastic Shrink Small Outline Package (SSOP) -40 to +85°C SA575DK SOT266-1 ABSOLUTE MAXIMUM RATINGS RATING SYMBOL PARAMETER SA575 VCC Single supply voltage VIN Voltage applied to any other pin –0.3 to (VCC+0.3) V TA Operating ambient temperature range -40 to +85 °C Storage temperature range -65 to +150 °C SOL 112 °C/W SSOP 117 °C/W TSTG θJA 1997 Nov 07 Thermal impedance –0.3 to 8 UNITS 2 V 853-1665 18666 Philips Semiconductors Product specification Low voltage compandor SA575 BLOCK DIAGRAM and TEST CIRCUIT 0.1µF VCC +5V C15 1 + 2 – C3 VOUT 575 VCC 19 – 18 OP AMP 10µF 4 VIN + C14 R13 OP AMP 3 + + GND 10µF 20 VREF 10k 17 3.8k C11 5 + CRECT 2.2µF 16 + 4.7µF 3.8k CRECT Σ 6 15 + + 2.2µF GND C6 VIN 7 + 10µF 8 VREF + 10µF Σ 10k ∆G 9 GND R8 30k 13 R7 12 10k GND + 30k C8 ∆G 10 10k GND VOUT 10µF 14 10k VREF C10 1µF 11 GND SR00704 Figure 2. Block Diagram and Test Circuit DC ELECTRICAL CHARACTERISTICS Typical values are at TA = 25°C. Minimum and Maximum values are for the full operating temperature range: -40 to +85°C for SA575, except SSOP package is tested at +25°C only. VCC = 5V, unless otherwise stated. Both channels are tested in the Expandor mode (see Test Circuit) LIMITS SYMBOL PARAMETER TEST CONDITIONS SA575 MIN TYP UNITS MAX For compandor, including summing amplifier VCC Supply voltage1 3 5 7 V ICC Supply current No signal 3 4.2 5.5 mA Reference voltage2 VCC = 5V 2.4 2.5 2.6 VREF RL Summing amp output load THD Total harmonic distortion ENO Output voltage noise 0dB Unity gain level VOS Output voltage offset Output DC shift Tracking error relative to 0dB 1997 Nov 07 10 V kΩ 1kHz, 0dB BW = 3.5kHz 0.12 1.5 % BW = 20kHz, RS = 0Ω 6 30 µV 1kHz -1.5 1.5 dB No signal -150 150 mV No signal to 0dB -100 100 mV Gain cell input = 0dB, 1kHz Rectifier input = 6dB, 1kHz -1.0 1.0 dB Gain cell input = 0dB, 1kHz Rectifier input = -30dB, 1kHz -1.0 1.0 dB 3 Philips Semiconductors Product specification Low voltage compandor DC ELECTRICAL CHARACTERISTICS SA575 (cont.) LIMITS SYMBOL PARAMETER TEST CONDITIONS SA575 MIN Crosstalk 1kHz, 0dB, CREF = 220µF UNITS TYP MAX -80 -65 dB For operational amplifier VO Output swing RL Output load CMR CMRR IB 600 0 Common-mode rejection ratio 60 Input bias current Input offset voltage AVOL Open-loop gain SR GBW ENI VCC-0.4 1kHz Input common-mode range VOS PSRR RL = 10kΩ VIN = 0.5V to 4.5V VCC V Ω VCC 80 -1 V dB 1 µA 3 mV RL = 10kΩ 80 dB Slew rate Unity gain 1 V/µs Bandwidth Unity gain 3 MHz Input voltage noise BW = 20kHz 2.5 µV Power supply rejection ratio 1kHz, 250mV 60 dB 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. 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. 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. 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 20kΩ 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. 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. 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 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 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. Equation 3. Compressor gain = 3.8k x 100µA 1/2 4VIN(avg) where VIN(avg) = 0.95VIN(RMS) Equation 4. Expandor gain = 4VIN(avg) 3.8k x 100µA τR = τA = 10k x CRECT = 10k x C4 AUTOMATIC LEVEL CONTROL where VIN(avg) = 0.95VIN(RMS) τR = τA = 10k x CRECT = 10k x C4 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. Equation 2. 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. 3.8k x 100µA ALC gain = 4VIN(avg) Equation 6. τR = τA = 10k x CRECT = 10k x C9 7 C5 10k 9 EXP IN 10µF ∆G 10k Σ 6 C3 EXP OUT 10µF 4 3.8k 5 C4 8 2.2µF VREF SR00705 Figure 3. Typical Expandor Configuration 1997 Nov 07 5 Philips Semiconductors Product specification Low voltage compandor SA575 R6 R7 30k 30k 1µF C7 VREF 8 12 Σ C12 C8 14 COMP OUT 13 10µF COMP IN 10k 10µF 11 ∆G 10k C13 16 3.8k 4.7µF 15 2.2µF C9 SR00706 Figure 4. Typical Compressor Configuration R6 R7 30k 30k 1µF C7 C COMP 22pF VREF 8 C12 ALC IN 12 Σ 14 13 10µF C8 ALC OUT 10µF 10k ∆ 11 G 10k C13 4.7µF 16 3.8k 16 C9 2.2µF SR00707 Figure 5. Typical ALC Configuration 1997 Nov 07 6 Philips Semiconductors Product specification Low voltage compandor SA575 VCC -5V C15 VREF 0.1µF C14 1 R1 C1 2 C2 + – R2 575 VCC OP AMP – 18 4 10µF 2.2µF 10µF C10 J2 16 ALC S1 4.7µF COMP 15 2.2µF Σ 7 14 10k C8 10µF 8 VREF 13 VREF R7 30k 10k C6 10µF 9 COMP/ ALC IN C11 C9 Σ 6 C12 C13 3.8k C4 C5 R11 17 3.8k 5 EXP IN 19 R12 10k 47µF R10 C3 J1 + OP AMP 3 EXP OUT 20 ∆G 12 R6 30k 10k ∆G 10 10k GND 10µF COMP/ ALC OUT C7 1µF 11 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 UNITY GAIN ERROR (dB) 0.5 0.4 0.3 0.2 VCC 7V 0.1 0.0 VCC 5V –0.1 –0.2 –0.3 VCC 3V –0.4 –0.5 VCC 2V –0.6 –0.7 –0.8 –0.9 –1.0 –50 –25 0 25 50 75 100 TEMPERATURE (°C) a. Unity Gain Error vs Temperature and VCC 4.4 4.2 4.0 I (mA) CC VCC 7V 3.8 3.6 VCC 5V 3.4 VCC 3V VCC 2V 3.2 3.0 –50 –25 0 25 50 75 100 TEMPERATURE (°C) b. ICC vs Temperature and VCC Figure 7. Temperature and VCC Curves 1997 Nov 07 8 SR00709 Philips Semiconductors Product specification Low voltage compandor SA575 TYPICAL PERFORMANCE CHARACTERISTICS GENERAL DIAGRAM 8 4.7µF 10µF 6 10dB IN INPUT (20–20kHz) 4 ∆G REC SUM OUTPUT 2 VCC = 5V 0dB IN 0 OUTPUT LEVEL (dB) –2 –4 –6 –8 –10 –12 –14 –16 –18 -40dB IN –20 –22 10 100 1000 10000 FREQUENCY (Hz) SR00710 Figure 8. Compressor Output Frequency Response 1997 Nov 07 30000 9 Philips Semiconductors Product specification Low voltage compandor SA575 TYPICAL PERFORMANCE CHARACTERISTICS (continued) 8 INPUT (20–20kHz) 6 GENERAL DIAGRAM 2.5dB IN 4.7µF REC 4 OUTPUT SUM 2 ∆G 10µF 0dB IN VCC = 5V 0 OUTPUT LEVEL (dB) –2 –4 –6 –8 –10 –12 –14 –16 –18 -10dB IN –20 –22 10 100 1000 10000 FREQUENCY (Hz) SR00711 Figure 9. Expandor Output Frequency Response 1997 Nov 07 30000 10 Philips Semiconductors Product specification Low voltage compandor SA575 COMPRESSOR IN EXPANDOR OUT +10dB +10dB +5dB 0dB 100mV 100mV 0dB 0dB –5dB –10dB –10dB –10dB –15dB –20dB –20dB –20dB –25dB –30dB –30dB –40dB –40dB –50dB –50dB } } COMPRESSION EXPANSION Figure 10. The Companding Function 1997 Nov 07 11 SR00712 Philips Semiconductors Product specification Low voltage compandor SA575 SO20: plastic small outline package; 20 leads; body width 7.5 mm 1997 Nov 07 12 SOT163-1 Philips Semiconductors Product specification Low voltage compandor SA575 SSOP20: plastic shrink small outline package; 20 leads; body width 4.4 mm 1997 Nov 07 13 SOT266-1 Philips Semiconductors Product specification Low voltage compandor SA575 DEFINITIONS Data Sheet Identification Product Status Definition Objective Specification Formative or in Design This data sheet contains the design target or goal specifications for product development. Specifications may change in any manner without notice. Preliminary Specification Preproduction Product 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. Product Specification Full 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. 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. Copyright Philips Electronics North America Corporation 1997 All rights reserved. Printed in U.S.A. Philips Semiconductors 811 East Arques Avenue P.O. Box 3409 Sunnyvale, California 94088–3409 Telephone 800-234-7381 1997 Nov 07 14