MAX8678

www.DataSheet4U.com 19-0786; Rev 0; 4/07 White LED Charge Pump with 1.1W Audio Amplifier General Description The MAX8678 integrates a charge pump for white lightemitting diodes (LEDs) with an audio loudspeaker amplifier. The high-efficiency, adaptive charge pump drives up to four LEDs with constant current for uniform brightness. The LED current is adjustable from 0.1mA/LED to 24mA/LED in 31 pseudo-logarithmic steps through a single-wire serial-pulse interface. High accuracy and LED-to-LED current matching are maintained throughout the adjustment range. Individual adaptive mode switching for each LED provides high efficiency with a wide range of LED forward voltages. The mono class AB audio amplifier directly drives an 8Ω loudspeaker with 1.1W RMS continuous power from a 5V supply with less than 1% THD+N. The gain is adjustable from -9dB to +18dB in ten 3dB steps through a singlewire serial-pulse interface. Clicks and pops are suppressed during on/off and all gain adjustments. Differential inputs improve common-mode noise rejection. The MAX8678 includes soft-start, thermal shutdown, open-circuit and short-circuit protection, and is available in the 16-pin, 3mm x 3mm Thin QFN package (0.8mm max height). Features ♦ High-Efficiency White LED Charge Pump Individual Adaptive Supply for Each LED 4 Low-Dropout LED Current Regulators 24mA to 0.1mA Dimming Range Single-Wire, Serial-Pulse Dimming Interface 1% (typ) Accuracy Low 140µA Quiescent Current ♦ Mono Class AB Audio Amplifier ...