Out in Front: July 18, 1996

A single-channel audio attenuator package maintains input-signal fidelity as it attenuates the signal level in 1-dB selectable steps over 0 to -62 dB. National Semiconductor's LM1971, with 3-dB bandwidth of more than 200 kHz, is a digitally controlled device that also includes a >100-dB mute function. Applications include communications systems, cellular phones and pagers, and audio-mixing systems.

The interface between the eight-pin DIP or SOIC IC and the system is via a three-wire serial interface at TTL or CMOS levels. The device's internal circuitry handles signals having dynamic range as high as 115 dB and eliminates clicks and pops when you change the attenuation setting. The LM1971 requires a single supply from 4.5 to 12V and costs $2.25 (1000).

—by Bill Schweber

National Semiconductor Corp, Santa Clara, CA, (800) 272-9959, http://www.national.com.