National Semiconductor's New Boomer

Integrated Filterless 2.2W Amplifier Offers Flexible I2C Compatible Controls

National Semiconductor Corporation today introduced a Boomer audio subsystem that combines a 2.2W stereo Class D audio amplifier with National's programmable 3D sound enhancement, automatic headphone detection and a 155 mW, stereo output capacitor-less (OCL) headphone amplifier. The subsystem is well-suited for portable media players, portable DVD players and multimedia cell phones.

National's fully integrated LM49270 filterless subsystem with high output power provides a flexible I2C compatible serial interface to quickly adjust the integrated circuit for multiple application requirements. Its headphone detection feature allows the subsystem to automatically switch between speaker and headphone mode. The LM49270's stereo headphone amplifier can be configured as either a capacitive-coupled or OCL device for more design options. With the OCL architecture, designers can eliminate the bulky, expensive output coupling capacitors required by traditional headphone amplifiers.

The subsystem also provides a wide, 32-step volume control for the headphone and speaker output levels. The LM49270 has 4.7 mA quiescent power in headphone mode to extend the battery life and delivers 2.2W of output power into a 4-Ohm load with less than 10 percent total harmonic distortion plus noise (THD+N) for a 5V supply - National Semiconductor.