National audio op amps promise industry’s lowest distortion, highest linearity

Two new op amp families for high-end audio applications from National Semiconductor set new standards for performance. The ±17 V/34 V LME497xx (single, dual, and quad versions available) family and the ±22 V/44 V LME49860 dual device offer extremely low distortion, low noise, high speed, and high output drive. High-performance devices are needed in audio systems, where the serial string of amplifiers in a signal path will contribute cumulative deficiencies, usually analyzed via worst-case or root-sum-square error budgets.

In addition to the 0.00003% THD+N (total harmonic distortion plus noise) specification , the op amps come with voltage noise of just 2.7 nV/root-Hz and current noise of 1.2 pA/root-Hz at 1 kHz. Input bias current is also low, at 10 nA. Output current is up to 26 mA (44 V devices) and 45 mA (34 V devices), and the amplifiers can handle 600 Ω loads. Gain bandwidth product of 55 MHz, 1/f noise corner at 60 Hz, and slew rate of ± round out the key specifications. PSRR and CMRR are 120 dB.

These audio op amp families come in a variety of packages, including SOIC, DIP, and metal can. Per-IC pricing ranges from $1.35 for the LME49710 single to $9.95 for the LME49720 in a metal can, and $3.36 for the LME49860 (all in 100-piece orders).

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