MAX1984

19-2761; Rev 0; 1/03 KIT ATION EVALU E L B A AVAIL Ultra-High-Efficiency White LED Drivers General Description Features o Synchronous Step-Up Regulator Achieves >95% Efficiency Internal Switch and Synchronous Rectifier Eliminates External MOSFETs and Diodes 1MHz Fixed Frequency Minimizes Component Sizes o o o o Up to 90% Total LED Efficiency Accurate LED Current Matching (8% max) Adjustable Maximum LED Current Multimode Dimming Control Digital Pulse-Width Modulation Control 2-Bit Parallel Control 3-Bit Parallel Control Analog Control o Selectively Enable LEDs o Open-LED Detection o Unique 0.5mA LED Test Mode o 2.7V to 5.5V Input Supply Range o Small 4mm x 4mm 20-Pin Thin QFN Package MAX1984/MAX1985/MAX1986 The MAX1984/MAX1985/MAX1986 are white light-emitting diode (LED) drivers that use individual regulators to control the current of up to eight LEDs. A high-efficiency step-up regulator generates just enough voltage to keep all the current regulators in regulation. A versatile dimming interface accommodates analog, digitally adjusted pulse-width modulation (DPWM), or parallel control. The individual current regulators allow good current matching between LEDs. Open or shorted LEDs cannot affect the performance of other LEDs. The step-up regulator achieves high efficiency by using synchronous rectification. The internal N-channel switch and P-channel synchronous rectifier eliminate the need for external MOSFETs and diodes. The 1MHz switching frequency allows the use of low-...