The AAT3113/4 are low noise, constant frequency charge pump DC/DC converters that use fractional (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°F flying capacitors and two small bypass capacitors at V IN and OUT) make the AAT3113/4 ideally suited for small battery-power applications. AnalogicTech’s Simple Serial Control™ (S²Cwire™) interface is used to enable, disable, and set the LED drive current for a 32-level logarithmic scale LED brightness control. The AAT3113/4 have a thermal management system to protect the device in the event of a short circuit condition on any of the output pins. Built-in soft-start circuitry prevents excessive inrush current during start-up. High switching frequency enables the use of small external capacitors. A low-current shutdown feature disconnects the load from V IN and reduces quiescent current to less than 1µA. The AAT3113 provides four LED current source outputs, and the AAT3114 provides six. The AAT3113/4 are available in 16-pin quad QFN packages; the AAT3113 is also available in a 12-pin TSOPJW package.