The LTC1911 is a switched capacitor step-down DC/DC converter that produces a 1.5V or 1.8V regulated output from a 2.7V to 5.5V input. The part uses switched capacitor fractional conversion to achieve high efficiency over the entire input range. No inductors are required. Internal circuitry controls the step-down conversion ratio to optimize efficiency as the input voltage and load conditions vary. Typical efficiency is over 25% higher than that of a linear regulator.A unique constant frequency architecture provides a low noise regulated output as well as lower input noise than conventional charge pump regulators. High frequency operation (fOSC= 1.5MHz) simplifies output filtering to further reduce conducted noise. To optimize efficiency,the part enters Burst Mode®operation under light load conditions.Low operating current (180µA with no load, 10µA in shutdown) and low external parts count (two 1µF flying capacitors and two 10µF bypass capacitors) make the LTC1911 ideally suited for space constrained battery powered applications. The part is short-circuit and over temperature protected, and is available in an 8-pin MSOP package.ApplicationsHandheld ComputersCellular PhonesSmart Card ReadersPortable Electronic EquipmentHandheld Medical InstrumentsLow Power DSP Supplies