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Class D speaker amp has dual-mode volume control

Posted: 08 Nov 2007 ?? ?Print Version ?Bookmark and Share

Keywords:Class D speaker amplifier? DC/DC converter? spread-spectrum? GPS?


Maxim Integrated Products has introduced the MAX9768, a highly efficient, 10W, mono, single-supply, Class D speaker amplifier with a versatile, analog/digital volume control.

Class D architecture enables this device to operate over a 4.5-14V supply-voltage range. This wide voltage range allows direct battery operation in portable applications, eliminating the need for a DC/DC converter between the battery and speaker amplifier. Additionally, the amplifier's 87-percent efficiency eliminates the need for heat sinks.

To further reduce BOM cost, the MAX9768 uses Maxim's patented filterless, spread-spectrum modulation technique, which minimizes EMI-radiated emissions and eliminates the need for the bulky, costly inductor-capacitor filters typically required to achieve acceptable EMI performance. MAX9768 significantly reduces overall solution size and cost, thus making it well suited for battery-operated equipment, TVs, PCs, GPS and personal/security radios.

MAX9768 is said to be the industry's first Class D amplifier to integrate flexible, dual-mode volume control, which enables either analog or digital control of a 64-step volume-control circuit. Analog control can be achieved using a DC voltage, potentiometer, filtered MCU PWM signal or other analog signal. Digital control is possible using the on-board I?C-compatible interface.

The MAX9768 delivers up to 10W of output power into an 8 speaker with a 14V supply, and features high 77dB PSRR, low 0.08 percent THD+N, and SNR up to 97dB. Additionally, it provides robust short-circuit and thermal-overload protection, comprehensive click-and-pop suppression and a low-power shutdown mode.

Fully specified over the -40C to 85C extended temperature range, MAX9768 is available in a small, 4mm x 4mm, 28-pin TQFN package. Prices start at $1.20 for 1,000 unit pieces.

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