AIC1842 Datasheet | Analog Intergrations Corporation

FEATURES 1MHz Switching Frequency 2.7V to 5.5V Input Voltage Range Low Shutdown Current: ≦1µA Regulated 20m A 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 20m A 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 tiny external ponents. The AIC1841 is available in a 12-pin thin QFN package, and the AIC1842 is available in a spacesaving 16-pin QFN package. Analog Integrations Corporation 3A1, No.1 Li-Hsin Rd. I, Science Park, Hsinchu 300, Taiwan TEL: 886-3-5772500 FAX: 886-3-5772510 .analog..tw DS-1842P-02 041707 TYPICAL APPLICATION CIRCUIT AIC1841/2 VIN 2.7V~5.5V Cin 1u F 4 C1u FFLY1 5 10 6 Cout 11 1u F 9 C1+ C2+ C1- C2- VIN D1 D2 EN/SET D3 GND AIC1841 D4 7 8 C1u FLFY2 12 LED1 1 2 LED2 3 LED3 LED4 VIN 2.7V~5.5V Cin 1u F 6 1Cu FFLY1 7 14 9 Cout 15 1u F 12 8...