LMC1983 Datasheet, PDF (1/14 Pages) National Semiconductor (TI) – Digitally-Controlled Stereo Tone and Volume Circuit with Three Selectable Stereo Inputs

August 1992
LMC1983
Digitally-Controlled Stereo Tone and Volume Circuit with
Three Selectable Stereo Inputs
General Description
The LMC1983 is a monolithic integrated circuit that provides
volume, balance, tone (bass and treble), loudness controls
and selection between three pairs of stereo inputs. These
functions are digitally controlled through a three-wire com-
munication interface. There are two digital inputs for easy in-
terface to other audio peripherals such as stereo decoders.
The LMC1983 is designed for line level input signals
(300 mV–2V) and has a maximum gain of −0.5 dB. Volume
is set at minimum and tone controls are flat when supply volt-
age is first applied.
Low noise and distortion result from using analog switches
and poly-silicon resistor networks in the signal path.
Additional tone control can be achieved using the LMC835
stereo 7-band graphic equalizer connected to the
LMC1983’s SELECT OUT/SELECT IN external processor
loop.
Features
n Low noise and distortion
n Three pairs of stereo inputs
n Loudness compensation
n 40 position 2 dB/step volume attenuator plus mute
n Independent left and right volume controls
n Low noise-suitable for use with DNR^® and Dolby^® noise
reduction
n External processor loop
n Signal handling suitable for compact discs
n Pop-free switching
n Serially programmable: INTERMETAL bus (IM) interface
n 6V to 12V single supply operation
n 28 Pin DIP or PLCC Package
Applications
n Stereo television
n Music reproduction systems
n Sound reinforcement systems
n Electronic music (MIDI)
n Personal computer audio control
Block Diagram
DNR^® is a registered trademark of National Semiconductor Corporation.
Dolby^® is a registered trademark of Dolby Labs.
© 1999 National Semiconductor Corporation DS011279
DS011279-1
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