DirectDrive HEADPHONE AMP FOR PORTABLE AUDIO EQUIPMENT OPERATES DOWN TO 0.9V
SUNNYVALE, CA-February 10, 2004-Maxim Integrated Products
(NASDAQ: MXIM) expands its DirectDrive headphone amplifier series with the introduction of the MAX9721A/MAX9721B/MAX9721C devices. The MAX9721 operates from a 0.9V to 1.8V single supply, allowing the device to be powered directly from a single AA or AAA battery. These headphone amps employs a ground-referenced output from a single supply, eliminating the two bulky DC-blocking capacitors typically required between the amplifier and headphone. Eliminating the DC-blocking capacitors also improves the low-frequency response of the amplifier, allowing full-range audio reproduction-especially important for music playback. The MAX9721 is ideal for single-cell portable audio equipment such as PDAs, MP3 players, and Smart Phones where board space and height are critical. Like Maxim's other DirectDrive headphone amps, the MAX9721 does not require a DC bias voltage to be applied to the headphone-jack ground pin, thus simplifying end-product design and reliability.
An 80dB at 1kHz power-supply rejection ratio (PSRR) allows this device to operate from noisy digital supplies without an additional linear regulator. The MAX9721 consumes only 2.2mA of supply current, has short-circuit and thermal-overload protection, and is specified over the -40°C to +85°C extended temperature range. Internal fixed gains of -2V/V (MAX9721A), -1.5V/V (MAX9721B), and -1V/V (MAX9721C) further reduce external component count.
The DirectDrive architecture extends the MAX9721's output dynamic range, delivering 20mW per channel into a 32 load with VDD of 1.5V. The typical THD+N is 0.006% and the outputs include ±8kV ESD protection. Comprehensive click-and-pop circuitry suppresses audible clicks and pops on start-up and shutdown. A low-power shutdown mode reduces supply current to 1.0µA to extend battery life.
The MAX9721 is available in a tiny 12-bump (1.54mm x 2.02mm x 0.6mm) UCSP™ and a 12-pin (4mm x 4mm x 0.8mm) TQFN package. Prices start at $0.65 (100,000-up, FOB USA). An evaluation kit is available to facilitate system design.
UCSP is a trademark of Maxim Integrated Products.
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