Stereo Subsystem Provides Rich, Loud Sound From A Li-Ion Battery

A high-efficiency, high-power, stereo Class D speaker amplifier; a DirectDrive stereo headphone amplifier; and an ultra-low-noise, analog bypass switch are combined in the MAX9879, a stereo audio subsystem chip. Not only that, but the MAX9879 employs the company’s third-generation, ultra-low-EMI, Class D amplifier technologies to provide Class AB audio performance with Class D efficiency. It delivers 715 mW of output power from a 3.7-V supply into an 8-? load with 88% (maximum) efficiency. The MAX9879 is suited for cellular phones, portable media players (PMPs), and other applications that require high audio quality, output power, and efficiency. The company’s DirectDrive architecture produces a ground-referenced output from a single supply, thus eliminating the need for large DC-blocking capacitors. To further save cost and space, the MAX9879 combines the company’s Class D technologies, active-emissions limiting, and spread-spectrum modulation, to significantly reduce EMI and eliminate the output filters typically required by Class D amplifiers. Additionally, the integrated low-noise, analog DPST audio switch allows users to bypass the Class D amplifier for reduction of power consumption in portable devices, thus eliminating the need for an external switch. The MAX9879 comes in a 2.5-mm x 3-mm, 30-bump UCSP that is fully specified over the -40°C to +85°C extended temperature range. Prices start at $1.35 each in lots of 1000. An evaluation kit is available. MAXIM INTEGRATED PRODUCTS, Sunnyvale, CA. (800) 998-8800.