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.