LM4670 Datasheet | National Semiconductor

Description The LM4670 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 external ponent count, simplifies circuit design, and reduces board area. The LM4670 processes analog inputs with a deltasigma modulation technique that lowers output noise and THD when pared to conventional pulse width modulators. The LM4670 is designed to meet the demands of mobile phones and other portable munication devices. Operating on a single 5V supply, it is capable of driving a 4Ω speaker load at a continuous average output of 2.3W with less than 1% THD+N. Its flexible power supply requirements allow operation from 2.4V to 5.5V. The LM4670 has high efficiency with speaker loads pared to a typical Class AB amplifier. With a 3.6V supply driving an 8Ω speaker, the IC’s efficiency for a 100m W power level is 77%, reaching 88% at 600m W output power. The LM4670 features a low-power consumption shutdown mode. Shutdown may be enabled by driving the Shutdown pin to a logic low (GND). The gain of the LM4670 is externally configurable which allows independent gain control from multiple sources by summing the signals. Key Specifications j Efficiency at 3.6V, 100m W into 8Ω speaker 77% (typ) j Efficiency at 3.6V, 600m W into 8Ω speaker 88% (typ) j Efficiency at 5V, 1W into 8Ω speaker j Quiescent current, 3.6V supply j Total shutdown power supply current j Single supply range 87% (typ) 4.8m A (typ) 0.01µA (typ) 2.4V to 5.5V Features n n n n n n n n No output filter required for inductive loads Externally configurable gain Very fast turn on time: 1.35ms (typ) Minimum external ponents "Click and pop" suppression circuitry Micro-power shutdown mode Short circuit protection Available in space-saving micro SMD and LLP packages Applications n Mobile phones n PDAs n Portable electronic devices Typical Application FIGU...