LM1973N

Manufacturer Part NumberLM1973N
DescriptionMicro-Pot 3-Channel 76 dB Audio Attenuator with Mute
ManufacturerNational Semiconductor
LM1973N datasheet
 


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LM1973
µPot
3-Channel 76dB Audio Attenuator with Mute
General Description
The LM1973 is a digitally controlled 3-channel 76dB audio
attenuator fabricated on a CMOS process. Each channel
has attenuation steps of 0.5dB from 0dB–15.5dB, 1.0dB
steps from 16dB–47dB, and 2.0dB steps from 48dB– 76dB,
with a mute function attenuating 104dB. Its logarithmic at-
tenuation curve can be customized through software to fit
the desired application.
The performance of a µPot
is demonstrated through its ex-
cellent 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 at-
tenuation settings are pop free.
The LM1973’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
LM1973 allows multiple µPots to be daisy-chained together,
reducing the number of enable and data lines to be routed
for a given application.
Typical Application
FIGURE 1. Typical Audio Attenuator
Application Circuit
µPot
and Overture
are trademarks of National Semiconductor Corporation.
© 1999 National Semiconductor Corporation
DS011958
Key Specifications
n Total Harmonic Distortion + Noise:
n Frequency response:
n Attenuation range (excluding mute):
n Differential attenuation:
n Signal-to-noise ratio (ref. 4 Vrms):
n Channel separation:
Features
n 3-wire serial interface
n Daisy-chain capability
n 104dB mute attenuation
n Pop and click free attenuation changes
Applications
n Automated studio mixing consoles
n Music reproduction systems
n Sound reinforcement systems
n Electronic music (MIDI)
n Personal computer audio control
Connection Diagram
Dual-In-Line Plastic or
Surface Mount Package
DS011958-1
Top View
Order Number LM1973M or LM1973N
See NS Package Number M20B or N20A
December 1994
0.003% (max)
100 kHz (−3dB) (min)
76dB (typ)
±
0.25dB (max)
110dB (min)
110dB (typ)
DS011958-2
www.national.com

LM1973N Summary of contents