AIC1841

AIC1841/2 High Efficiency 1.5X charge Pump For White LEDs Backlighting FEATURES 1MHz Switching Frequency 2.7V to 5.5V Input Voltage Range Low Shutdown Current: ≦1µA Regulated 20mA Full-Scale Output Current 32-Position Linear Scale with Digital Control High Accuracy Brightness Matching 33% Less Input Current Than Doubler Charge Pump No Inductors Required Build-in Soft-Start Current Limit and Over Temperature Protection 12-Pin (AIC1841) and 16-Pin (AIC1842) QFN Package APPLICATIONS Cellular Phones PDAs Digital Still Cameras Handheld Devices White LED Backlighting GENERAL DESCRIPTION The AIC1841 and AIC1842 provide 4 and 6 LED current source outputs with regulated constant current for uniform intensity. The AIC1841/2 is the low noise, constant frequency charge pump DC/DC converter that uses 1.5X conversion to increase efficiency in white LED applications. The devices can be used to produce current levels up to 20mA for each output from a 2.7V to 5.5V input. Low external parts counts (two 1 μ F flying capacitors and two small bypass capacitors at VIN, and OUT) make the AIC1841/2 ideal for small, battery-powered applications. EN/SET interface is used to enable, disable and set the LED current for a 32 level logic scale LED brightness control. Built-in current limiting, with thermal shutdown provide protection to the AIC1841/2 against fault conditions. Automatic softstart circuitry prevents excessive inrush current during start-up. 1MHz high switching frequency is enable to use t...