LM1973

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SNAS093B – DECEMBER 1994 – REVISED MARCH 2013

LM1973 µPot 3-Channel 76dB Audio Attenuator with Mute

Check for Samples: LM1973

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FEATURES

DESCRIPTION

The LM1973 is a digitally controlled 3-channel 76dB

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•

3-Wire Serial Interface

audio attenuator fabricated on a CMOS process.

•

Daisy-Chain Capability

Each channel has attenuation steps of 0.5dB from

•

104dB Mute Attenuation

0dB–15.5dB, 1.0dB steps from 16dB–47dB, and

2.0dB steps from 48dB– 76dB, with a mute function

•

Pop and Click Free Attenuation Changes

attenuating 104dB. Its logarithmic attenuation curve

can be customized through software to fit the desired

APPLICATIONS

application.

•

Automated Studio Mixing Consoles

The performance of a

μPot is demonstrated through

•

Music Reproduction Systems

its excellent Signal-to-Noise Ratio, extremely low

•

Sound Reinforcement Systems

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

μPot

contains a mute function that disconnects the input

•

Electronic Music (MIDI)

signal

from

the

output,

providing

a

minimum

•

Personal Computer Audio Control

attenuation

of

96dB.

Transitions

between

any

attenuation settings are pop free.

KEY SPECIFICATIONS

The LM1973's 3-wire serial digital interface is TTL

•

Total Harmonic Distortion + Noise: 0.003 %

and CMOS compatible; receiving data that selects a

(max)

channel and the desired attenuation level. The Data-

Out pin of the LM1973 allows multiple

μPots to be

•

Frequency response: 100 kHz (

−3dB) (min)

daisy-chained together, reducing the number of

•

Attenuation range (excluding mute): 76 dB

enable and data lines to be routed for a given

(typ)

application.

•

Differential attenuation: ±0.25 dB (max)

•

Signal-to-noise ratio (ref. 4 Vrms): 110 dB

(min)

•

Channel separation: 110 dB (typ)

TYPICAL APPLICATION

CONNECTION DIAGRAM

Top View

Figure 1. Typical Audio Attenuator

Application Circuit

Figure 2. PDIP and SOIC Packages

See Package Numbers NFH0020A and DW0020B

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Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

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PRODUCTION DATA information is current as of publication date.

Copyright © 1994–2013, Texas Instruments Incorporated

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.