SSM2143

a FEATURES High Common-Mode Rejection DC: 90 dB typ 60 Hz: 90 dB typ 20 kHz: 85 dB typ Ultralow THD: 0.0006% typ @ 1 kHz Fast Slew Rate: 10 V/ s typ Wide Bandwidth: 7 MHz typ (G = 1/2) Two Gain Levels Available: G = 1/2 or 2 Low Cost 12k Ω –IN –6 dB Differential Line Receiver SSM2143 FUNCTIONAL BLOCK DIAGRAM 6k Ω SENSE V+ VOUT V– 12k Ω +IN 6kΩ REFERENCE SSM2143 PIN CONNECTIONS Epoxy Mini-DIP (P Suffix) and SOIC (S Suffix) REF –IN +IN V– 1 2 3 4 8 NC GENERAL DESCRIPTION The SSM2143 is an integrated differential amplifier intended to receive balanced line inputs in audio applications requiring a high level of immunity from common-mode noise. The device provides a typical 90 dB of common-mode rejection (CMR), which is achieved by laser trimming of resistances to better than 0.005%. Additional features of the device include a slew rate of 10 V/µs and wide bandwidth. Total harmonic distortion (THD) is less than 0.004% over the full audio band, even while driving low impedance loads. The SSM2143 input stage is designed to handle input signals as large as +28 dBu at G = 1/2. Although primarily intended for G = 1/2 applications, a gain of 2 can be realized by reversing the +IN/–IN and SENSE/REFERENCE connections. When configured for a gain of 1/2, the SSM2143 and SSM2142 Balanced Line Driver provide a fully integrated, unity gain solution to driving audio signals over long cable runs. For similar performance with G = 1, see SSM2141. SSM2143 TOP VIEW (NOT TO SCALE) 7 V+ 6 VOUT 5 SENSE OP-482 NC = NO CONNECT REV. 0 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 which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 617/329-4700 Fax: 617/326-8703 15 V, –40 C ≤ ≤ 85 SSM2143–SPECIFICATIONS (V = specifications Tapply+at TC,=G+=251/2,) unless otherwise noted. Typical C S A A Parameter AUDIO PERFORMANCE Total Harmonic Distortion Plus Noise Signal-to-Noise Ratio Headroom DYNAMIC RESPONSE Slew Rate Small Signal Bandwidth Symbol THD+N SNR HR SR BW–3 dB Conditions VIN = 10 V rms, RL = 10 kΩ, f = 1 kHz 0 dBu = 0.775 V rms, 20 kHz BW, RTI Clip Point = 1% THD+N RL = 2 kΩ, CL = 200 pF RL = 2 kΩ, CL = 200 pF G = 1/2 G=2 VCM = 0 V, RTI, G = 2 VCM = ± 10 V, RTO f = dc f = 60 Hz f = 20 kHz f = 400 kHz VS = ± 6 V to ± 18 V Common Mode Differential RL = 2 kΩ Min Typ 0.0006 –107.3 +28.0 Max Units % dBu dBu V/µs MHz MHz 6 10 7 3.5 INPUT Input Offset Voltage Common-Mode Rejection VIOS CMR –1.2 70 0.05 90 90 85 60 110 ± 15 ± 28 ± 14 2 300 +45, –20 0.03 18 ± 10 +1.2 mV dB dB dB dB dB V V V kΩ pF mA Power Supply Rejection Input Voltage Range OUTPUT Output Voltage Swing Minimum Resistive Load Drive Maximum Capacitive Load Drive Short Circuit Current Limit GAIN Gain Accuracy REFERENCE INPUT Input Resistance Voltage Range POWER SUPPLY Supply Voltage Range Supply Current Specifications subject to change without notice. PSR IVR 90 VO ISC ± 13 –0.1 0.1 % kΩ V VS ISY VCM = 0 V, RL = ∞ ±6 ± 2.7 ± 18 ± 4.0 V mA Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 18 V Common-Mode Input Voltage . . . . . . . . . . . . . . . . . . . . ± 22 V Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . . ± 44 V Output Short Circuit Duration . . . . . . . . . . . . . . .Continuous Operating Temperature Range . . . . . . . . . . . . –40°C to +85°C Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C Junction Temperature (TJ) . . . . . . . . . . . . . . . . . . . . +150°C Lead Temperature (Soldering, 60 sec) . . . . . . . . . . . . +300°C Thermal Resistance 8-Pin Plastic DIP (P): θJA = 103, θJC = 43 . . . . . . . . . °C/W 8-Pin SOIC (S): θJA = 150, θJC = 43. . . . . . . . . . . . . . °C/W ABSOLUTE MAXIMUM RATINGS ORDERING GUIDE Model Operating Temperature Range Package Description Package Option SSM2143P –40°C to +85°C SSM2143S* –40°C to +85°C *Contact sales office for availability. 8-Pin Plastic DIP N-8 8-Pin SOIC SO-8 –2– REV. 0 SSM2143 1µs 100 9 0 100 90 1 0 0 % 10 0% 50mV Figure 1. Small-Signal Transient Response (VIN = ±200 mV, G = 1/2, RL = 2 kΩ, VS = ± 15 V, TA = +25 °C) 5V 5µs Figure 2. Large Signal Transient Response (VIN = +24 dBu, G = 1/2, RL = 2 kΩ VS = ± 15 V, TA = +25 °C) Figure 3. THD+N vs. Frequency (VS = ± 15 V, VIN = 10 V rms, with 80 kHz Filter) Figure 4. Headroom (VS = ± 15 V, RL = 10 kΩ, with 80 kHz Filter) 1.0 0.1 THD+N – % 0.01 0.001 0.0001 100 1k 10k 100k LOAD RESISTANCE – Ω Figure 5. Dynamic Intermodulation Distortion, DIM-100 (VS = ± 15 V, RL = 100 kΩ) Figure 6. THD+N vs. Load (VS = ± 15 V, VIN = 10 V rms, with 1 kHz Sine, 80 kHz Filter) REV. 0 –3– SSM2143 40 VS = ±15V TA = +25°C 30 CLOSED-LOOP GAIN – dB 20 VS = ±15V TA = +25°C 10 0 –10 –20 –30 100 1k 10k 100k 1M 10M FREQUENCY – Hz Figure 7. Closed-Loop Gain vs. Frequency, 20 Hz to 20 kHz (Gain of 1/2 Normalized to 0 dB) Figure 8. Closed-Loop Gain vs. Frequency, 100 Hz to 10 MHz 180 135 90 TA = +25°C VS = ±15V COMMON-MODE REJECTION – dB 120 VS = ±15V TA = +25°C RL = 2kΩ 100 PHASE – Degrees 80 45 0 –45 –90 60 40 20 –135 –180 100 0 100 1k 10k 100k FREQUENCY – Hz 1M 10M 1k 10k FREQUENCY – Hz 100k 1M Figure 9. Closed-Loop Phase vs. Frequency Figure 10. Common-Mode Rejection vs. Frequency 140 10 POWER SUPPLY REJECTION – dB 120 100 VS = ±15V TA = +25°C 8 OUTPUT IMPEDANCE – Ω VS = ±15V TA = +25°C 80 –PSRR 60 +PSRR 40 20 6 4 2 0 10 100 1k 10k FREQUENCY – Hz 100k 1M 0 100 1k 10k FREQUENCY – Hz 100k 1M Figure 11. Power Supply Rejection vs. Frequency Figure 12. Closed-Loop Output Impedance vs. Frequency –4– REV. 0 SSM2143 6 TA = +25°C VS = ±15V G = 1/2 RL = 2kΩ 12.5V TA = +25°C VS = ±15V 10.0V OUTPUT VOLTAGE SWING – V rms 5 4 OUTPUT VOLTAGE SWING – V rms 10M 7.5V 3 5.0V 2 1 2.5V 0 1k 10k 100k FREQUENCY – Hz 1M 0V 10 100 1k 10k LOAD RESISTANCE – Ω Figure 13. Output Voltage Swing vs. Frequency Figure 14. Output Voltage Swing vs. Load Resistance 40 TA = +25°C 120 OUTPUT VOLTAGE SWING – V p–p VOLTAGE NOISE DENSITY – nV/ Hz 100 VS = ±15V TA = +25°C 30 80 20 60 40 10 20 0 0 ±5 ±10 SUPPLY VOLTAGE ±15 ±20 0 1 10 100 FREQUENCY – Hz 1k 10k Figure 15. Output Voltage Swing vs. Supply Voltage Figure 16. Voltage Noise Density vs. Frequency 1s 100 90 100 9 0 10ms 0.5µV 0V –0.5µV 10 0 % 1 0 0 % 5µV 0V –5µV 5mV Figure 17. Low Frequency Voltage Noise from 0.1 Hz to 10 Hz* 5mV Figure 18. Voltage Noise from 0 kHz to 1 kHz* *The photographs in Figure 17 through Figure 19 were taken at V S = ± 15 V and T A = +25°C, using an external amplifier with a gain of 1000. REV. 0 –5– SSM2143 16 VS = ±15V R L = 2kΩ 14 1ms 100 9 0 SLEW RATE – V/µs 12 5µV 0V –5µV 1 0 0 % 10 8 6 5mV 4 –50 –25 0 50 25 TEMPERATURE – °C 75 100 Figure 19. Voltage Noise from 0 kHz to 10 kHz* Figure 20. Slew Rate vs. Temperature 0.10 VS = ±15V VIN = ±10V 400 VS = ±15V INPUT OFFSET VOLTAGE – µV 0.08 R S = 0Ω 300 GAIN ERROR – % 0.06 200 0.04 100 0.02 0 –50 –25 25 50 0 TEMPERATURE – °C 75 100 0 –50 –25 0 25 50 75 100 TEMPERATURE – °C Figure 21. Gain Error vs. Temperature Figure 22. Input Offset Voltage vs. Temperature 5 VS = ±15V 4 SUPPLY CURRENT – mA SUPPLY CURRENT– mA 4.0 TA = +25°C 3.5 3.0 3 2.5 2 2.0 1 1.5 0 –50 –25 0 50 25 TEMPERATURE – °C 1.0 75 100 0 ±5 ±10 ±15 SUPPLY VOLTAGE – V ±20 Figure 23. Supply Current vs. Temperature Figure 24. Supply Current vs. Supply Voltage *The photographs in Figure 17 through Figure 19 were taken at V S = ± 15 V and T A = +25°C, using an external amplifier with a gain of 1000. –6– REV. 0 SSM2143 APPLICATIONS INFORMATION The SSM2143 is designed as a balanced differential line receiver. It uses a high speed, low noise audio amplifier with four precision thin-film resistors to maintain excellent common-mode rejection and ultralow THD. Figure 25 shows the basic differential receiver application where the SSM2143 yields a gain of 1/2. The placement of the input and feedback resistors can be switched to achieve a gain of +2, as shown in Figure 26. For either circuit configuration, the SSM2143 can also be used unbalanced by grounding one of the inputs. In applications requiring a gain of +1, use the SSM2141. +15V 0.1µF +15V 0.1µF Setting ∆R to 5 Ω results in the CMRR of 71 dB, as stated above. To achieve the SSM2143’s CMRR of 90 dB, the resistor mismatch can be at most 0.57 Ω. In other words, to build this circuit discretely, the resistors would have to be matched to better than 0.005%! The following table shows typical resistor accuracies and the resulting CMRR for a differential amplifier. % Mismatch 5% 1% 0.1% 0.005% DC OUTPUT LEVEL ADJUST CMRR 30 dB 44 dB 64 dB 90 dB 12k –IN 2 7 6k 5 A V =1 2 7 6k –IN 5 SSM2143 12k 2 6 12k 3 AV = 2 SSM2143 12k +IN 3 4 + 6k 6 VOUT 1 +IN 1 6k 4 VOUT The reference node of the SSM2143 is normally connected to ground. However, it can be used to null out any dc offsets in the system or to introduce a dc reference level other than ground. As shown in Figure 28, the reference node needs to be +15V 0.1µF +10V OP27 0.1µF 0.1µF –15V –15V 12k –IN 2 7 6k 5 –10V Figure 25. Standard Configuration for Gain of 1/2 CMRR Figure 26. Reversing the Resistors Results in a Gain of 2 SSM2143 12k +IN 3 4 0.1µF 6k 6 VOUT REFERENCE 1 The internal thin-film resistors are precisely trimmed to achieve a CMRR of 90 dB. Any imbalances introduced by the external circuitry will cause a significant reduction in the overall CMRR performance. For example, a 5 Ω source imbalance will result in a CMRR of 71 dB at dc. This is also true for any reactive source impedances that may affect the CMRR over the audio frequency range. These error sources need to be minimized to maintain the excellent CMRR. To quantify the required accuracy of the thin film resistor matching, the source of CMRR error can be analyzed. A resistor mismatch can be modelled as shown in Figure 27. By assuming a tolerance on one of the 12 kΩ resistors of ∆R, the equation for the common-mode gain becomes: –15V Figure 28. A Low Impedance Buffer Is Required to Adjust the Reference Voltage. buffered with an op amp to maintain very low impedance to achieve high CMRR. The same reasoning as above applies such that the 6 kΩ resistor has to be matched to better than 0.005% or 0.3 Ω. The op amp maintains very low output impedance over the entire audio frequency range, as long as its bandwidth is well above 20 kHz. The reference input can be adjusted over a ± 10 V range. The gain from the reference to the output is unity so the resulting dc output adjustment range is also ± 10 V. INPUT ERRORS  VOUT 6k 6k  6k = +1 – V IN 6k + 12k  12k + ∆R  12k + ∆R   which reduces to: VOUT 1/3 ∆R = VIN 12k + ∆R This gain error leads to a common-mode rejection ratio of: The main dc input offset error specified for the SSM2143 is the Input Offset Voltage. The Input Bias Current and Input Offset Current are not specified as for a normal operational amplifier. Because the SSM2143 has built-in resistors, any bias current related errors are converted into offset voltage errors. Thus, the offset voltage specification is a combination of the amplifier’s offset voltage plus its offset current times the input impedance. +18V ALL CABLE MEASUREMENTS USE BELDEN CABLE (500'). +18V 0.1µF 7 2 SSM2142 1 8 3 2 5 SSM2143 4 1 –18V –18V 6 VOUT CMRR = |ADM| 18k ≅ |ACM| ∆R 6k VIN 6 4 12k + ∆R –IN 12k +IN 6k CMRR = VOUT 18k ∆R 3 7 5 0.1µF Figure 27. A Small Mismatch in Resistance Results in a Large Common-Mode Error Figure 29. SSM2142/SSM2143 Balanced Line Driver/ Receiver System REV. 0 –7– SSM2143 LINE DRIVER/RECEIVER SYSTEM The following data demonstrates the typical performance of the two parts together, measured on an Audio Precision at the SSM2143’s output. This configuration was tested with 500 feet 500' CABLE NO CABLE Figure 30. THD+N vs. Frequency of SSM2142/SSM2143 System (VS = ± 18 V, VIN = 5 V rms, with 80 kHz Filter) Figure 33. SSM2142/SSM2143 System Frequency Response (VS = ± 18 V, VIN = 0 dBV, 500' Cable) 5V 100 90 10 0% 10µs Figure 31. SSM2142/SSM2143 System Headroom– See Text—(VS = ± 18 V, RL = 10 kΩ, 500' Cable) 500' CABLE OUTLINE DIMENSIONS Dimensions shown in inches and (mm). N-8 8 5 SO-8 0.280 (7.11) 0.240 (6.10) 1 4 8 5 0.430 (10.92) 0.348 (8.84) 0.070 (1.77) 0.045 (1.15) 0.060 (1.52) 0.015 (0.38) 0.150 (3.81) MIN PIN 1 0.1574 (4.00) 0.1497 (3.80) 1 4 0°- 8° 0.325 (8.25) 0.300 (7.62) 0.2440 (6.20) 0.2284 (5.80) 0.0500 (1.27) 0.0160 (0.41) NO CABLE 0.210 (5.33) MAX 0.200 (5.05) 0.125 (3.18) 0.1968 (5.00) 0.1890 (4.80) 0.0196 (0.50) × 45° 0.0099 (0.25) 0.0688 (1.75) 0.0532 (1.35) 0.0098 (0.25) 0.0075 (0.19) SEATING PLANE SEE DETAIL ABOVE 0.015 (0.381) 0.008 (0.204) 0.0098 (0.25) 0.0040 (0.10) Figure 32. SSM2142/SSM2143 System DIM-100 Dynamic Intermodulation Distortion (VS = ± 18 V, RL = 10 kΩ) 0.022 (0.558) 0.014 (0.356) 0.100 (2.54) BSC SEATING PLANE 0 - 15 0.0500 (1.27) BSC 0.0192 (0.49) 0.0138 (0.35) –8– REV. 0 PRINTED IN U.S.A. Figure 34. SSM2142/SSM2143 System Large Signal Pulse Response (VS = ± 18 V, RL = 10 kΩ, No Cable) C1598–24–11/91 The SSM2143 and SSM2142 provide a fully integrated line driver/ receiver system. The SSM2142 is a high performance balanced line driver IC that converts an unbalanced input into a balanced output signal. It can drive large capacitive loads on long cables making it ideal for transmitting balanced audio signals. When combined with an SSM2143 on the receiving end of the cable, the system maintains high common-mode rejection and ultralow THD. The SSM2142 is designed with a gain of +2 and the SSM2143 with a gain of 1/2, providing an overall system gain of unity. of cable between the ICs as well as no cable. The combination of the two parts results in excellent THD+N and SNR and a noise floor of typically –105 dB over a 20 Hz to 20 kHz bandwidth. A comment on SSM2142/SSM2143 system headroom is necessary. Figure 31 shows a maximum signal handling of approximately ± 22 dBu, but it must be kept in mind that this is measured between the SSM2142’s input and SSM2143’s output, which has been attenuated by one half. Normally, the system would be shown as actually used in a piece of equipment, whereby the SSM2143 is at the input and SSM2142 at the output. In this case, the system could handle differential signals in excess of +24 dBu at the input and output, which is consistent with headroom requirements of most professional audio equipment.