1FEATURES

2• 3-Wire Serial Interface

• Daisy-Chain Capability

• 104dB Mute Attenuation

• Pop and Click Free Attenuation Changes

APPLICATIONS

• Automated Studio Mixing Consoles

• Music Reproduction Systems

• Sound Reinforcement Systems

• Electronic Music (MIDI)

• Personal Computer Audio Control

KEY SPECIFICATIONS

• Total Harmonic Distortion +

Noise: 0.003 % (max)

• Frequency response: 100 kHz (−3dB) (min)

• Attenuation range (excluding

mute): 78 dB (typ)

• Differential attenuation: ±0.25 dB (max)

• Signal-to-noise ratio

(ref. 4 Vrms): 110 dB (min)

• Channel separation: 100 dB (min)

DESCRIPTION

The LM1972 is a digitally controlled 2-channel 78dB

audio attenuator fabricated on a CMOS process.

Each channel has attenuation steps of 0.5dB from

0dB–47.5dB, 1.0dB steps from 48dB–78dB, with a

mute function attenuating 104dB. Its logarithmic

attenuation curve can be customized through

software to fit the desired application.

The performance of a μPot is demonstrated through

its excellent Signal-to-Noise Ratio, extremely low

THD+N), and high channel separation. Each μPot

contains a mute function that disconnects the input

signal from the output, providing a minimum

attenuation of 96dB. Transitions between any attenuation settings are pop free.

The LM1972's 3-wire serial digital interface is TTL

and CMOS compatible; receiving data that selects a

channel and the desired attenuation level. The Data-

Out pin of the LM1972 allows multiple μPots to be

daisy-chained together, reducing the number of

enable and data lines to be routed for a given

application.