The LM4666 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 LM4666 processes analog inputs with a delta-sigma modulation technique that lowers output noise and THD when compared to conventional pulse width modulators.

The LM4666 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 450mW with less than 1%THD+N. Its flexible power supply requirements allow operation from 2.8V to 5.5V.

The LM4666 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 79%, reaching 84% at 450mW output power.

The LM4666 features a low-power consumption shutdown mode. Shutdown may be enabled by driving the Shutdown pin to a logic low (GND).

The LM4666 has fixed selectable gain of either 6dB or 12dB. The LM4666 has short circuit protection against a short from the outputs to VDD or GND.

• No Output Filter Required for Inductive Transducers
• Selectable Gain of 6dB or 12dB
• Very Fast Turn On Time: 6ms (typ)
• Minimum External Components
• "Click and Pop" Suppression Circuitry
• Micro-Power Shutdown Mode
• Short Circuit Protection
• Available in Space-Saving NHK0014A Package

Key Specifications

• Efficiency at 3V, 100mW into 8? Transducer: 79% (typ)
• Efficiency at 3V, 450mW into 8? Transducer: 84% (typ)
• Efficiency at 5V, 1W into 8? Transducer: 85% (typ)
• Total Quiescent Power Supply Current: 7.0mA (typ)
• Total Shutdown Power Supply Current: 0.02µA (typ)
• Single supply range: 2.8V to 5.5V