The AP5725 is a step-up DC/DC converter specifically designed to drive white LEDs with a constant current. The device can drive 2~6 LEDs in series from a Li-Ion cell. Series connection of the LEDs provides identical LED currents resulting in uniform brightness and eliminates the need for ballast resistors. The AP5725 switches at 1.2MHz that allows the use of tiny external components. A low 0.25V feedback voltage minimizes power loss in the current setting resistor for better efficiency.