LM4667

LM4667 Filterless High Efficiency 1.3W Switching Audio Amplifier September 2004 LM4667 Filterless High Efficiency 1.3W Switching Audio Amplifier General Description The LM4667 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 LM4667 processes analog inputs with a delta-sigma modulation technique that lowers output noise and THD when compared to conventional pulse width modulators. The LM4667 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 8Ω transducer loads at a continuous average output of 450mW with less than 1%THD+N. Its flexible power supply requirements allow operation from 2.7V to 5.5V. The LM4667 has high efficiency with an 8Ω 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 450mW output power. The LM4667 features a low-power consumption shutdown mode. Shutdown may be enabled by driving the Shutdown pin to a logic low (GND). The LM4667 has fixed selectable gain of either 6dB or 12dB. The LM4667 has short circuit protection against a short from the outputs to VDD, GND, or across the outputs. Key Specifications j Efficiency at 3V, ...