Class D Audio Amp Works Without Filter

Reducing parts count, the LM4667 fixed-gain, Class D audio amplifier requires no output filter and comes in a nine-bump, micro SMD package. A unique modulator is said to be responsible for eliminating the output filter required by typical switching amplifiers. Processing analog inputs with a delta-sigma modulation technique, the device operates from a single 3V supply (2.7V to 5.5V tolerant) and can drive 8? transducer loads at a continuous average output of 450 mW with less than 1% THD+N. Price is $0.48 each/1,000. NATIONAL SEMICONDUCTOR CORP., Santa Clara, CA. (800) 272-9959.