Analogue, Mixed Signal, LSI


Stereo Class D speaker amplifier

17 September 2008 Analogue, Mixed Signal, LSI

The MAX9744 from Maxim is a 20 W stereo Class D speaker amplifier which operates from a 4,5 V to 14 V power supply. The wide supply range minimises the cost of portable designs by reducing component count and allowing the use of a smaller battery pack. The device provides ample output power throughout the power-supply voltage range, making it ideally suited for MP3 docking stations, gaming consoles and flat-panel televisions.

The MAX9744 integrates 64-step analog and digital volume control. In analog mode, the volume range is ratiometric relative to VDD. To ramp up or down the volume digitally, the system microcontroller can program a 6-bit register through the chip’s I²C interface.

External feedback resistors set the input gain, while the output has an internally set gain. When powered from a 12 V supply, the MAX9744 combines these gains with the wide volume-control range, and delivers 20 W per channel into 4 Ω speakers.

Class D amplifiers are known for high power efficiency, and the MAX9744 features 93% efficiency while delivering 20 W into an 8 Ω load. It achieves 75 dB PSRR, 0,04% THD+N, and greater than 90 dB SNR. The IC includes a low-power shutdown mode, a mute function and integrated click-and-pop suppression.

Available in a 7 x 7 x 0,8 mm, 44-pin TQFN package, the IC is fully specified over the -40°C to +85°C temperature range. An evaluation kit is available to speed design implementation.

For more information contact Larry Gordon, CST Electronics, +27 (0)11 608 0070, [email protected], www.cstelectronics.co.za



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