20W Class D Stereo Amp Operates From 4.5V To 14V Supply July 23, 2008
Introduced as the industry's first 20W stereo Class D speaker amplifier to operate from a 4.5V to 14V power supply, the MAX9744’s wide supply range minimizes the cost of portable designs by reducing component count and allowing the use of a smaller battery pack. The device also 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 six-bit register through the amp's I2C interface. External feedback resistors set the input gain while the output gain is internally set. Working from a 12V supply, the device combines these gains with the wide volume-control range and delivers 20W per channel into 4-Ohm speakers. Other features include a 93% efficiency while delivering 20W into an 8-Ohm load, a 75-dB PSRR, 0.04% THD+N, a greater than 90-dB SNR, low-power shutdown mode, mute function, and click-and-pop suppression. Available in a 7 mm x 7 mm x 0.8 mm, 44-pin TQFN package, pricing starts at $2.45 each/1000. MAXIM INTEGRATED PRODUCTS, Sunnyvale, CA. (800) 998-8800.
