The LM4664 is a fully integrated single-supply high efficiency switching audio amplifier. It features an innovative modulator that eliminates the LC output filter used with typical switching amplifiers. Eliminating the output filter reduces parts count, simplifies circuit design, and reduces board area. The LM4664 processes analog inputs with a delta-sigma modulation technique that lowers output noise and THD when compared to conventional pulse width modulators. The LM4664 is designed to meet the demands of mobile phones and other portable communication devices. Operating on a single 3V supply, it is capable of driving 8 transducer loads at a continuous average output of 425mW with less than 1%THD+N. Its flexible power supply requirements allow operation from 2.7V to 5.5V. The LM4664 has high efficiency with an 8 transducer load compared to a typical Class AB amplifier. With a 3V supply, the IC's efficiency for a 100mW power level is 74%, reaching 84% at 425mW output power.