a FEATURES Excellent Noise Performance:. nv/ Hz or.5 db Noise Figure Ultra-low THD: <.% @ G = Over the Full Audio Band Wide Bandwidth: MHz @ G = High Slew Rate: V/ s @ G = V rms Full-Scale Input, G =, V S = V Unity Gain Stable True Differential Inputs Subaudio /f Noise Corner -Lead PDIP or -Lead SOIC Only One External Component Required Very Low Cost Extended Temperature Range: C to +5 C APPLICATIONS Audio Mix Consoles Intercom/Paging Systems -Way Radio Sonar Digital Audio Systems +IN RG RG Self-Contained Audio Preamplifier SSM9 FUNCTIONAL BLOCK DIAGRAM IN V PIN CONNECTIONS -Lead PDIP (N Suffix) -Lead Narrow Body SOIC (RN Suffix)* V+ OUT REFERENCE V GENERAL DESCRIPTION The SSM9 is a latest generation audio preamplifier, combining SSM preamplifier design expertise with advanced processing. The result is excellent audio performance from a monolithic device, requiring only one external gain set resistor or potentiometer. The SSM9 is further enhanced by its unity gain stability. Key specifications include ultra-low noise (.5 db noise figure) and THD (<.% at G = ), complemented by wide bandwidth and high slew rate. Applications for this low cost device include microphone preamplifiers and bus summing amplifiers in professional and consumer audio equipment, sonar, and other applications requiring a low noise instrumentation amplifier with high gain capability. RG IN +IN V 3 SSM9 TOP VIEW (Not to Scale) 7 5 RG V+ OUT REFERENCE -Lead Wide Body SOIC (RW Suffix) NC RG NC 3 IN +IN 5 NC V 7 NC NC 5 RG NC SSM9 3 V+ TOP VIEW (Not to Scale) NC OUT REFERENCE 9 NC NC = NO CONNECT *Consult factory for availability. Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective companies. One Technology Way, P.O. Box 9, Norwood, MA -9, U.S.A. Tel: 7/39-7 www.analog.com Fax: 7/-33 Analog Devices, Inc. All rights reserved.
SSM9 SPECIFICATIONS (V S = 5 V and C T A +5 C, unless otherwise noted. Typical specifications apply at T A = 5 C.) Parameter Symbol Conditions Min Typ Max Unit DISTORTION PERFORMANCE V O = 7 V rms R L = kw Total Harmonic Distortion Plus Noise THD + N f = khz, G =.7 % f = khz, G =.5 % f = khz, G =.35 % f = khz, G =.5 % BW = khz NOISE PERFORMANCE Input Referred Voltage Noise Density e n f = khz, G =. nv/ Hz f = khz, G =.7 nv/ Hz f = khz, G = 7 nv/ Hz f = khz, G = 5 nv/ Hz Input Current Noise Density i n f = khz, G = pa/ Hz DYNAMIC RESPONSE Slew Rate SR G = V/ms R L = kw C L = pf Small Signal Bandwidth BW 3 db G = khz G = khz G = khz G = khz INPUT Input Offset Voltage V IOS.5.5 mv Input Bias Current I B V CM = V 3 ma Input Offset Current Ios V CM = V ±. ±. ma Common-Mode Rejection CMR V CM = ± V G = 3 db G = 9 3 db G = 7 9 db G = 5 7 db Power Supply Rejection PSR V S = ± 5 V to ± V G = db G = db G = 9 db G = 7 db Input Voltage Range IVR ± V Input Resistance R IN Differential, G = MW G = 3 MW Common Mode, G = 5.3 MW G = 7. MW OUTPUT Output Voltage Swing V O R L = kw, T A = 5 C ± 3.5 ± 3.9 V Output Offset Voltage V OOS 3 mv Maximum Capacitive Load Drive 5 pf Short Circuit Current Limit I SC Output-to-Ground Short ± 5 ma Output Short Circuit Duration Continuous sec GAIN Gain Accuracy kw R G = T A = 5 C G R G = W, G =.5. db R G = W, G =.5. db R G =. kw, G =.5. db R G =, G =.. db Maximum Gain G 7 db REFERENCE INPUT Input Resistance kw Voltage Range ± V Gain to Output V/V POWER SUPPLY Supply Voltage Range V S ± 5 ± V Supply Current I SY V CM = V, R L = ±. ± 7.5 ma V CM = V, V S = ± V, R L = ±.7 ±.5 ma Specifications subject to change without notice.
SSM9 ABSOLUTE MAXIMUM RATINGS Supply Voltage................................ ±9 V Input Voltage.......................... Supply Voltage Output Short Circuit Duration................... sec Storage Temperature Range............ 5 C to +5 C Junction Temperature (T J )............. 5 C to +5 C Lead Temperature Range (Soldering, sec)........ 3 C Operating Temperature Range........... C to +5 C Thermal Resistance -Lead PDIP (N)....................... JA = 9 C/W..................................... JC = 37 C/W -Lead SOIC (RW).................... JA = 9 C/W..................................... JC = 7 C/W NOTES Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. q JA is specified for worst-case mounting conditions, i.e., q JA is specified for device in socket for PDIP; q JA is specified for device soldered to printed circuit board for SOIC package. CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as V readily accumulate on the human body and test equipment and can discharge without detection. Although the SSM9 features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. WARNING! ESD SENSITIVE DEVICE Typical Performance Characteristics THD + N %.... G = G = G = G = 5V V S V 7Vrms V O Vrms R L BW = khz k k k TPC. Typical THD + Noise vs. Gain RTI, VOLTAGE NOISE DENSITY nv/ Hz T A = 5 C V S = 5V G =. k k TPC. Voltage Noise Density vs. Frequency 3
SSM9 RTI VOLTAGE NOISE DENSITY nv/ Hz. GAIN V S = 5V f = khz OR khz TPC 3. RTI Voltage Noise Density vs. Gain k IMPEDANCE 9 7 5 3 k k k TPC. Output Impedance vs. Frequency M PEAK-TO-PEAK VOLTAGE V 3 5 5 R L = k V S = 5V GAIN GAIN = k k k TPC 5. Maximum Output Swing vs. Frequency M OUTPUT VOLTAGE V V S = 5V G G = INPUT SWING (V IN+ V IN ) V 3 f = khz OUTPUT SWING (V OUT+ V OUT ) V 5 5 k k LOAD RESISTANCE k 3 SUPPLY VOLTAGE (V + V ) V 3 SUPPLY VOLTAGE (V + V ) V TPC. Output Voltage vs. Load Resistance TPC 7. Input Voltage Range vs. Supply Voltage TPC. Output Voltage Range vs. Supply Voltage CMRR db V CM = mv V S = 5V T A = 5 C G = G = G = G = k k k FREQUENCY Hz TPC 9. CMRR vs. Frequency +PSRR db 5 5 75 5 5 V CM = mv V S = 5V G = k k G = G = G = k TPC. Positive PSRR vs. Frequency PSRR db 5 5 75 5 5 G = V S = mv V S = 5V G = G = G = k k k TPC. Negative PSRR vs. Frequency
SSM9..35 V+/V = 5V.. T A = 5 C V+/V = 5V.3 V IOS mv.5..5 V IOS mv...3 V OOS mv 3 5...5.5 7 5 5 5 5 75 TEMPERATURE C TPC. V IOS vs. Temperature. 5 5 5 3 35 SUPPLY VOLTAGE (V CC V EE ) V TPC 3. V IOS vs. Supply Voltage 5 5 5 5 75 TEMPERATURE C TPC. V OOS vs. Temperature 3 T A = 5 C 5 V+/V = 5V 5 T A = 5 C V OOS mv I B A 3 I B+ OR I B I B A 3 3 5 5 5 3 35 SUPPLY VOLTAGE (V CC V EE ) V TPC 5. V OOS vs. Supply Voltage 5 5 5 5 75 TEMPERATURE C TPC. I B vs. Temperature 3 SUPPLY VOLTAGE (V CC V EE ) V TPC 7. I B vs. Supply Voltage SUPPLY CURRENT ma I+ @ V+/V = V I+ @ V+/V = 5V I @ V+/V = 5V I @ V+/V = V SUPPLY CURRENT ma T A = 5 C I+ I SUPPLY CURRENT ma 5 5 5 5 75 TEMPERATURE C TPC. Supply Current vs. Temperature 5 5 5 3 35 SUPPLY VOLTAGE (V CC V EE ) V TPC 9. Supply Current vs. Supply Voltage 5 5 SUPPLY VOLTAGE V TPC. I SY vs. Supply Voltage 5
SSM9 +IN V+ V S = 5V T A = 5 C IN V OUT G = (+IN) ( IN) = R G k R G + R G SSM9 OUT R G REFERENCE Figure. Basic Circuit Connections V VOLTAGE GAIN db GAIN The SSM9 only requires a single external resistor to set the voltage gain. The voltage gain, G, is: kw G = + R G and the external gain resistor, R G, is: k R = W G G For convenience, Table I lists various values of R G for common gain levels. Table I. Values of R G for Various Gain Levels R G ( ) A V db NC.7 k 3.. k 33 3.3 3 3 3 5 The voltage gain can range from to 35. A gain set resistor is not required for unity gain applications. Metal film or wire-wound resistors are recommended for best results. The total gain accuracy of the SSM9 is determined by the tolerance of the external gain set resistor, R G, combined with the gain equation accuracy of the SSM9. Total gain drift combines the mismatch of the external gain set resistor drift with that of the internal resistors ( ppm/ C typ). Bandwidth of the SSM9 is relatively independent of gain, as shown in Figure. For a voltage gain of, the SSM9 has a small-signal bandwidth of khz. At unity gain, the bandwidth of the SSM9 exceeds MHz. k k k M M Figure. Bandwidth for Various Values of Gain NOISE PERFORMANCE The SSM9 is a very low noise audio preamplifier exhibiting a typical voltage noise density of only nv/ Hz at khz. The exceptionally low noise characteristics of the SSM9 are in part achieved by operating the input transistors at high collector currents since the voltage noise is inversely proportional to the square root of the collector current. Current noise, however, is directly proportional to the square root of the collector current. As a result, the outstanding voltage noise performance of the SSM9 is obtained at the expense of current noise performance. At low preamplifier gains, the effect of the SSM9 voltage and current noise is insignificant. The total noise of an audio preamplifier channel can be calculated by: E = e + ( i R ) + e n n n S t where: E n = total input referred noise e n = amplifier voltage noise i n = amplifier current noise R S = source resistance e t = source resistance thermal noise For a microphone preamplifier, using a typical microphone impedance of 5 W, the total input referred noise is: En = ( nv Hz ) + ( pa / Hz 5 W ) + (. nv / Hz ) = 93. nv/ Hz @ khz where: e n = nv/ Hz @ khz, SSM9 e n i n = pa/ Hz @ khz, SSM9 i n R S = 5 W, microphone source impedance e t =. nv/ Hz @ khz, microphone thermal noise This total noise is extremely low and makes the SSM9 virtually transparent to the user.
SSM9 INPUTS The SSM9 has protection diodes across the base emitter junctions of the input transistors. These prevent accidental avalanche breakdown, which could seriously degrade noise performance. Additional clamp diodes are also provided to prevent the inputs from being forced too far beyond the supplies. TRANSDUCER TRANSDUCER (INVERTING) (NONINVERTING) a. Single-Ended R R SSM9 SSM9 b. Pseudo-Differential Although the SSM9 inputs are fully floating, care must be exercised to ensure that both inputs have a dc bias connection capable of maintaining them within the input common-mode range. The usual method of achieving this is to ground one side of the transducer as in Figure 3a. An alternative way is to float the transducer and use two resistors to set the bias point as in Figure 3b. The value of these resistors can be up to kw, but they should be kept as small as possible to limit common-mode pickup. Noise contribution by resistors is negligible since it is attenuated by the transducer s impedance. Balanced transducers give the best noise immunity and interface directly as in Figure 3c. For stability, it is required to put an RF bypass capacitor directly across the inputs, as shown in Figures 3 and. This capacitor should be placed as close as possible to the input terminals. Good RF practice should also be followed in layout and power supply bypassing, since the SSM9 uses very high bandwidth devices. REFERENCE TERMINAL The output signal is specified with respect to the reference terminal, which is normally connected to analog ground. The reference may also be used for offset correction or level shifting. A reference source resistance will reduce the common-mode rejection by the ratio of 5 kw/r REF. If the reference source resistance is W, then the CMR will be reduced to 7 db (5 kw/ W = 7 db). TRANSDUCER c. True Differential SSM9 Figure 3. Three Ways of Interfacing Transducers for High Noise Immunity COMMON-MODE REJECTION Ideally, a microphone preamplifier responds to only the difference between the two input signals and rejects common-mode voltages and noise. In practice, there is a small change in output voltage when both inputs experience the same common-mode voltage change; the ratio of these voltages is called the common-mode gain. Common-mode rejection (CMR) is the logarithm of the ratio of differential-mode gain to common-mode gain, expressed in db. PHANTOM POWERING A typical phantom microphone powering circuit is shown in Figure. Z to Z provide transient overvoltage protection for the SSM9 whenever microphones are plugged in or unplugged. +V +IN R5 C3 7 F C R3.k % R.k % R k R k Z Z C pf IN C V C, C: F TO 7 F, 3V, TANTALUM OR ELECTROLYTIC Z Z: V, /W Z3 Z R G +V R G SSM9 R G V OUT Figure. SSM9 in Phantom Powered Microphone Circuit 7
SSM9 BUS SUMMING AMPLIFIER In addition to its use as a microphone preamplifier, the SSM9 can be used as a very low noise summing amplifier. Such a circuit is particularly useful when many medium impedance outputs are summed together to produce a high effective noise gain. The principle of the summing amplifier is to ground the SSM9 inputs. Under these conditions, Pins and are ac virtual grounds sitting about.55 V below ground. To remove the.55 V offset, the circuit of Figure 5 is recommended. A forms a servo amplifier feeding the SSM9 inputs. This places Pins l and at a true dc virtual ground. R in conjunction with C removes the voltage noise of A, and in fact just about any operational amplifier will work well here since it is removed from the signal path. If the dc offset at Pins l and is not too critical, then the servo loop can be replaced by the diode biasing scheme of Figure 5. If ac coupling is used throughout, then Pins and 3 may be directly grounded. + IN IN R.k C R3.33 F 33k A R 5.k C F SSM9 TO PINS AND 3 IN Figure 5. Bus Summing Amplifier V V OUT R5 k PRINTED IN U.S.A.
SSM9 OUTLINE DIMENSIONS. (.).35 (9.7).355 (9.). (5.33) MAX.5 (3.).3 (3.3).5 (.9). (.5). (.). (.3). (.5) BSC 5. (7.).5 (.35). (.).5 (.3) MIN SEATING PLANE.5 (.3) MIN. (.5) MAX.5 (.3) GAUGE PLANE.35 (.).3 (7.7).3 (7.).3 (.9) MAX.95 (.95).3 (3.3).5 (.9). (.3). (.5). (.).7 (.7). (.5).5 (.) COMPLIANT TO JEDEC STANDARDS MS- CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN. CORNER LEADS MAY BE CONFIGURED AS WHOLE OR HALF LEADS. Figure. -Lead Plastic Dual In-Line Package [PDIP] Narrow Body (N-) Dimensions shown in inches and (millimeters) 7-A.5 (.3). (.397) 9 7. (.99) 7. (.93).5 (.93). (.3937).3 (.). (.39) COPLANARITY.7 (.5) BSC.5 (.3).35 (.95)..5 (.) SEATING PLANE.33 (.3).3 (.). (.79).75 (.95).5 (.9) 5.7 (.5). (.57) COMPLIANT TO JEDEC STANDARDS MS-3-AA CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN. Figure 7. -Lead Standard Small Outline Package [SOIC_W] Wide Body (RW-) Dimensions shown in millimeters and (inches) 3-7-7-B 9
SSM9 5. (.9). (.9). (.57) 3. (.97) 5. (.) 5. (.).5 (.9). (.) COPLANARITY. SEATING PLANE.7 (.5) BSC.75 (.).35 (.53).5 (.).3 (.).5 (.9).7 (.7).5 (.9).5 (.99).7 (.5). (.57) 5 COMPLIANT TO JEDEC STANDARDS MS--AA CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN. Figure. -Lead Standard Small Outline Package [SOIC_N] Narrow Body (RN-) Dimensions shown in millimeters and (inches) 7-A ORDERING GUIDE Model Temperature Range Package Description Package Option SSM9BNZ C to +5 C -Lead PDIP N- SSM9BRNZ C to +5 C -Lead SOIC_N R- SSM9BRNZRL C to +5 C -Lead SOIC_N, REEL R- SSM9BRWZ C to +5 C -Lead SOIC_W RW- SSM9BRWZRL C to +5 C -Lead SOIC_W, REEL RW- Z = RoHS Compliant Part REVISION HISTORY / Rev. to Rev. A Updated Outline Dimensions... 9 Changes to Ordering Guide... /3 Revision : Initial Version 3 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D7--/(A)