LTC3251-1.5

U U LTC3251/ LTC3251-1.2/LTC3251-1.5 500mA High Efficiency, Low Noise, Inductorless Step-Down DC/DC Converter FEATURES ■ Up to 500mA Output Current ■ No Inductors ■ 2.7V to 5.5V Input Voltage Range ■ 2x Efficiency Improvement Over LDOs ■ 2-Phase, Spread Spectrum Operation for Low Input and Output Noise ■ Shutdown Disconnects Load from VIN ■ Adjustable Output Voltage Range: 0.9V to 1.6V Fixed Output Voltages: 1.2V, 1.5V ■ Super Burst, Burst and Burst Defeat Operating Modes ■ Low Operating Current: IIN = 35µA (Burst Mode® Operation) ■ Super Burst Operating Current: IIN = 10µA ■ Low Shutdown Current: IIN = 0.01µA Typ ■ Soft-Start Limits Inrush Current at Turn-On ■ Short-Circuit and Overtemperature Protected ■ Available in a Thermally Enhanced 10-Pin MSOP Package U APPLICATIO S ■ Handheld Devices ■ Cellular Phones ■ Portable Electronic Equipment ■ DSP Power Supplies DESCRIPTIO The LTC®3251/LTC3251-1.2/LTC3251-1.5 are 2-phase charge pump step-down DC/DC converters that produce a regulated output from a 2.7V to 5.5V input. The parts use switched capacitor fractional conversion to achieve twice the typical efficiency of a linear regulator. No inductors are required. VOUT is resistor programmable from 0.9V to 1.6V or fixed at 1.2V or 1.5V, with up to 500mA of load current available. A unique 2-phase spread spectrum architecture provides a very low noise regulated output as well as low noise at the input.* The parts have four operating modes: Continuous Spread Spectrum, Spread Spe...