LM1973

LM1973 www.ti.com SNAS093A – MAY 2004 – REVISED OCTOBER 2004 LM1973 µPot3-Channel 76dB Audio Attenuator with Mute Check for Samples: LM1973 FEATURES 1 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): 76 dB (typ) Differential attenuation: ±0.25 dB (max) Signal-to-noise ratio (ref. 4 Vrms): 110 dB (min) Channel separation: 110 dB (typ) 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 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 LM1973's 3-wire serial digital interface is TTL and CMOS compat...