Tiny, High-Power Audio Subsystem Runs On A Li-Ion Battery

Maxim claims its MAX9877 IC is the industry's smallest audio subsystem. The device combines a high-power, mono Class D speaker amplifier; a DirectDrive, stereo headphone amplifier; and a low-noise, bypass analog switch. It runs off a lithium-ion battery and delivers 725 mW of output power from a 3.7-V supply into an 8-ohm load with 85% (max) efficiency. The MAX9877 is well suited for cellular phones and portable media players. Maxim's patented DirectDrive architecture produces a ground-referenced output from a single supply, eliminating the need for large DC-blocking capacitors. To further save cost and space, the MAX9877 uses Maxim's active-emissions limiting and patented spread-spectrum modulation to reduce EMI and eliminate the output filters typically required by Class D amplifiers. It features input mixing, volume control, comprehensive click-and-pop suppression, and a flexible, user-defined input architecture with three preamplifier gain settings. The MAX9877 is packaged in a 2.5 mm x 2 mm 20-bump WLP that is fully specified over the -40 to +85°C extended temperature range. Prices start at $1.62 in 1000-unit quantities. An evaluation kit is also available. MAXIM INTEGRATED PRODUCTS, Sunnyvale, CA. (800) 998-8800.