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+OUT FORCE – OUT FORCE – OUT SENSE +OUT SENSE 10kW 10kW 50W 50W VIN GND ALL RESISTORS 30k W UNLESS OTHERWISE INDICATED 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. a Balanced Line Driver SSM2142

FEATURES

Transformer-Like Balanced Output Drives 10 V RMS Into a 600 V Load Stable When Driving Large Capacitive Loads and Long Cables Low Distortion 0.006% typ 20 Hz–20 kHz, 10 V RMS into 600 V High Slew Rate

15 V/ ms typ

(Differential or Single-Ended); 0.7% typ Outputs Short-Circuit Protected Available In Space-Saving 8-Pin Mini-DIP Package Low Cost

APPLICATIONS

Graphic and Parametric Equalizers Dynamic Range Processors Digital Effects Processors Telecommunications Systems Industrial Instrumentation Hi-Fi Equipment GENERAL DESCRIPTION The SSM2142 is an integrated differential-output buffer amplifier that converts a single-ended input signal to a balanced output signal pair with high output drive. By utilizing low noise thermally matched thin film resistors and high slew rate amplifiers, the SSM2142 helps maintain the sonic quality of audio systems by eliminating power line hum, RF interference, voltage drops, and other externally generated noise commonly encountered with long audio cable runs. Excellent rejection of common-mode noise and offset errors is achieved by laser trimming of the onboard resistors, assuring high gain accuracy. The carefully designed output stage of the SSM2142 is capable of driving difficult loads, yielding low distortion performance despite extremely long cables or loads as low as 600 Ω , and is stable over a wide range of operating conditions. Based on a cross-coupled, electronically balanced topology, the SSM2142 mimics the performance of fully balanced transformer-based solutions for line driving. However, the SSM2142 maintains lower distortion and occupies much less board space than transformers while achieving comparable common-mode rejection performance with reduced parts count. The SSM2142 in tandem with the SSM2141 differential receiver establishes a complete, reliable solution for driving and receiving audio signals over long cables. The SSM2141 features an Input Common-Mode Rejection Ratio of 100 dB at 60 Hz. Specifications demonstrating the performance of this typical system are included in the data sheet. REV. C

SSM2142–SPECIFICATIONS Parameter Symbol Conditions Min Typ Max Units INPUT IMPEDANCE ZIN 10 kΩ INPUT CURRENT IIN VIN = ± 7.071 V ± 750 ± 900 µA GAIN, DIFFERENTIAL 5.8 5.98 dB GAIN, SINGLE-ENDED Single-Ended Mode 5.7 5.94 dB GAIN ERROR, DIFFERENTIAL RL = 600 Ω 0.7 2 % POWER SUPPLY REJECTION RATIO STATIC PSRR V S = ± 13 V to ± 18 V 60 80 dB OUTPUT COMMON-MODE REJECTION OCMR See Test Circuit; f = 1 kHz –45 dB OUTPUT SIGNAL BALANCE RATIO SBR See Test Circuit; f = 1 kHz –40 dB TOTAL HARMONIC DISTORTION Plus Noise THD+N 20 Hz to 20 kHz, 0.006 % VO = 10 V rms, RL = 600 Ω SIGNAL-TO-NOISE RATIO SNR V IN = 0 V –93.4 dBu HEADROOM HR CLIP Level = 10.5 V rms +93.4 dBu SLEW RATE SR 15 V/µs OUTPUT COMMON-MODE VOLTAGE OFFSET1 VOOS RL = 600 Ω –250 25 250 mV DIFFERENTIAL OUTPUT VOLTAGE OFFSET VOOD RL = 600 Ω –50 15 50 mV DIFFERENTIAL OUTPUT VOLTAGE SWING VIN = ± 7.071 V ± 13.8 ± 14.14 V OUTPUT IMPEDANCE ZO 45 50 55 Ω SUPPLY CURRENT ISY Unloaded, VIN = 0 V 5.5 7.0 mA OUTPUT CURRENT, SHORT CIRCUIT I SC 60 70 mA NOTES 1Output common-mode offset voltage can be removed by inserting dc blocking capacitors in the sense lines. See Applications Information. Specifications subject to change without notice. (VS = 618 V, –40 8C ≤ TA ≤ +858C, operating in differential mode unless otherwise noted. Typical characteristics apply to operation at T A = +258C.) ABSOLUTE MAXIMUM RATINGS* Output Short Circuit Duration (Both Outputs) . . . . Indefinite *Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only; the functional operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. PIN CONNECTIONS 8-Pin Plastic DIP (P Suffix) –2– 16-Pin Wide Body SOL (S Suffix) – FORCE – SENSE GROUND VIN + FORCE + SENSE NC NC NC NC NC NC NC NC1 REV. C

–6– PRINTED IN U.S.A. THE CABLE PAIR The SSM2142 is capable of driving a 10 V rms signal into 600 Ω and will remain stable despite cable capacitances of up to 0.16 µF in either balanced or single-ended configurations. Low impedance shielded audio cable such as the standard Belden 8451 or similar is recommended, especially in applications traversing considerable distances. The user is cautioned that the so-called “audiophile” cables may incur four times the capac- itance per unit length of the standard industrial-grade product. In situations of extreme load and/or distance, adding a second parallel cable allows the user to trade off half of the total line resistance against a doubling in capacitive load. SINGLE-ENDED OPERATION The SSM2142 is designed to be compatible with existing balanced-pair interface systems. Just as in transformer-based circuits, identical but opposite currents are generated by the output pair which can be ground-referenced if desired and transmitted on a single wire. Single-ended operation requires that the unused side of the output pair be grounded to a solid return path in order to avoid voltage offset errors at the nearby input common. The signal quality obtained in these systems is directly dependent on the quality of the ground at each end of the wire. Also note that in single-ended operation the gain through the device is still 6 dB, and that the SSM2142 incurs no significant degradation in signal distortion or output drive capability, although the noise rejection inherent in balanced- pair systems is lost. POWER SUPPLY SEQUENCING A problem occasionally encountered in the interface system en- vironment involves irregular application of the supplies. The user is cautioned that applying power erratically can inadvert- ently bias parts of the circuit into a latch-up condition. The small geometries of an integrated circuit are easily breached and damaged by short-risetime spikes on a supply line, which usu- ally demonstrate considerable overshoot. The questionable practice of exchanging components or boards while under power can create such an undesirable sequence as well. Possible options which offer improved board-level device protection include: additional bypass capacitors, high-current reverse- biased steering diodes between both supplies and ground, vari- ous transient surge suppression devices, and safety grounding connectors. Likewise, power should be applied to the device before the output is connected to “live” systems which may carry voltages of sufficient magnitude to turn on the output devices of the SSM2142 and damage the device. In any case, of course, the user must always observe the absolute maximum ratings shown in the specifications. REV. C

Rev. C | Page 8 of 8

REVISION HISTORY

5/11—Rev. B to Rev. C Changes to Output Common-Mode Rejection Parameter and Output Signal Balance Ratio Parameter in ©1991–2011 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the prop erty of their respective owners. D01496-0-5/11(C)