Maxim MAX9744 20W D类放大方案

Maxim公司的MAX9744 是带有音量控制的立体声20W D类音频功率放大器,具有AB类放大器的性能和D类放大器的效率,从而节省了板的面积和不需要笨重的散热器. MAX9744的工作电压从4.5V到14V,在14V电源时每路能向4欧姆扬声器提供20W功率.本文介绍了MAX9744的主要性能,功能方框图以及I2C模式和模拟模式的典型应用电路图.

MAX9744:120W Stereo Class D Speaker Amplifier with Volume Control
The MAX9744 20W stereo Class D audio power amplifier provides Class AB amplifier performance with Class D efficiency, conserving board space and eliminating the need for a bulky heatsink. This device features single- supply operation, adjustable gain, shutdown mode, a SYNC output, speaker mute, and industry-leading click-and-pop suppression.

The MAX9744 features a 64-step dual-mode (analog or digital), programmable volume control and mute function. The MAX9744 operates from a 4.5V to 14V single supply and can deliver up to 20W per channel into a 4 ohm speaker with a 14V supply.

The MAX9744 offers two modulation schemes: a fixed frequency modulation mode that allows one of several preset switching frequencies to be selected, and a spread-spectrum modulation mode that helps to reduce EMI-radiated emissions.

The MAX9744 features high 75dB PSRR, low 0.04% THD+N, and SNR in excess of 90dB. Robust short-circuit and thermal-overload protection prevent device damage during a fault condition. The MAX9744 is available in a 44-pin thin QFN-EP (7mm x 7mm x 0.8mm)
package and is specified over the extended -40°C to +85°C temperature range.

MAX9744主要特性:
Wide 4.5V to 14V Power-Supply Voltage Range
Filterless Spread-Spectrum Modulation Lowers Radiated RF Emissions from Speaker Cables
20W Stereo Output (4, VDD = 12V, THD+N = 10%)
Integrated Volume Control (I2C or Analog)
Low 0.04% THD+N
High 75dB PSRR
High 93% Efficiency
Integrated Click-and-Pop Suppression
Low-Power Shutdown Mode
Short-Circuit and Thermal-Overload Protection
Available in a 44-Pin Thin QFN-EP (7mm x 7mm x 0.8mm)

MAX9744应用:
Flat-Panel Televisions
PC Speaker Systems
Multimedia Docking Stations




图1.MAX9744简化的功能图



图2.MAX9744功能方框图/I2C模式典型应用电路图



图3.MAX9744功能方框图/模拟模式典型应用电路图