Digitally-controlled 62 db audio attenuator with mute

The LM1971 is a digitally controlled single channel audio attenuator fabricated on a CMOS process. Attenuation is variable in 1 dB steps from 0 dB to −62 dB. A mute function disconnects the input from the output, providing over 100 dB of attenuation.

The performance of the device is exhibited by its ability to change attenuation levels without audible clicks or pops. In addition, the LM1971 features a low Total Harmonic Distortion (THD) of 0.0008%, and a Dynamic Range of 115 dB, making it suitable for digital audio needs. The LM1971 is available in both 8-pin plastic PDIP or SOIC packages.

The LM1971 is controlled by a TTL/CMOS compatible 3-wire serial digital interface. The active low LOAD line enables the data input registers while the CLOCK line provides system timing. Its DATA pin receives serial data on the rising edge of each CLOCK pulse, allowing the desired attenuation setting to be selected.