National Semiconductor LMC1992 Digitally-Controlled Stereo Tone and Volume Circuit Datasheet

The LMC1992 is a monolithic integrated circuit that provides four stereo inputs, bass and treble tone controls, and volume, balance, and front-rear fader controls. These functions are digitally controlled through a three-wire communication interface. All of the LMC1992's functions are achieved with only three external capacitors per channel. It is designed for line level input signals (300 mV to 2V) and has a maximum gain of 0 dB. Low noise and distortion result from using analog switches and thin-film silicon-chromium resistor networks in the signal path. Volume and fader are at minimum and tone controls are flat when supply voltage is first applied. Additional tone control can be achieved using the LMC835 stereo 7-band graphic equalizer connected to the LMC1992's select-out-select-in external processor loop. Features include low noise and distortion, four stereo inputs, 40 volume levels including mute, 20 fader levels, all attenuators have a 2 dB of attenuation per step, front-back fade control, external processor loop, only three external components per channel, serial programming.

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