1FEATURES

23• 3-Wire Serial Interface

• Mute Function

• Click and Pop Free Attenuation Changes

• 8-Pin Plastic PDIP and SOIC Packages

Available

APPLICATIONS

• Communication Systems

• Cellular Phones and Pagers

• Personal Computer Audio Control

• Electronic Music (MIDI)

• Sound Reinforcement Systems

• Audio Mixing Automation

KEY SPECIFICATIONS

• Total Harmonic Distortion 0.0008 % (Typ)

• Frequency Response > 200 kHz (−3 dB) (Typ)

• Attenuation Range (Excluding Mute) 62 dB

(Typ)

• Dynamic Range 115 dB (Typ)

• Mute Attenuation 102 dB (Typ)

DESCRIPTION

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.