The CAT3636 is a high efficiency fractional charge pump that can drive up to six LEDs programmable by a one wire digital interface. The inclusion of a 1.33x fractional charge pump mode increases device efficiency by up to 10% over traditional 1.5x charge pumps with no added external capacitors. Low noise input ripple is achieved by operating at a constant switching frequency which allows the use of small external ceramic capacitors. The multi-fractional charge pump supports a wide range of input voltages from 2.5 V to 5.5 V. The EN/SET logic input functions as a chip enable and a '1-wire' addressable interface for control and current setting of all LEDs. Three groups of two LEDs can be configured with independent LED currents between 0.25 mA and 32 mA.