GENERAL DESCRIPTION The ft2128 is a high-efficiency, high-performance, Class-D audio power amplifier with dual modes of automatic level control (ALC). It operates from 3.0V to 5.5V supply. When powered with 5V supply voltage, it is capable of delivering a continuous average output of 3.4W into 3Ω load or 2.8W into 4Ω load with 4% THD + N. The ft2128 features ALC on the audio output signals, which detects the output clipping caused by the over-level input signal and automatically adjusts the voltage gain of the amplifier to eliminate the clipping while maintaining the maximally-allowed dynamic range of the audio output signals. The ALC also eliminates the output clipping due to low battery supply voltage. As a Class-D audio power amplifier, the ft2128 features high efficiency up to 90%, which make the device ideal for use in battery-powered portable devices. It also features minimized click-and-pop noise during turn-on and turn-off transitions. APPLICATIONS? Portable navigation devices? Multimedia internet devices? Portable or Blue-tooth speakers FEATURES? Filterless Class-D operation? Automatic level control to eliminate output clipping? Dual ALC modes of operation? High efficiency up to 90%? Constant output power at 5V supply (ALC-1) 3.2 W (3Ω load, 1% THD + N) 2.6W (4Ω load, 1% THD + N) 1.4W (8Ω load, 1% THD + N)? Constant output power at 5V supply (ALC-2) 3.4W ( 3Ω load, 4% THD + N) 2.8W (4Ω load, 4% THD + N) 1.5W (8Ω load, 4% THD + N) ALC Range:? 12dB Low quiescent current:? 3mA @ VDD = 3.6V? Analog or digital scheme to set ALC operating mode? Short-circuit & thermal overload protection? Available in SOP-8L & MSOP-8L packages APPLICATION CIRCUIT 470nF 470nF VREF Generator CTRL optional