LTC3251 500mA High Efficiency, Low Noise, Inductorless Step-Down DC/DC Converters

Product Details

The LTC3251/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 Spectrum with Burst Mode operation, Super Burst mode operation and shutdown.

Low operating current (35µA in Burst Mode operation, 10µA in Super Burst mode operation) and low external parts count make the LTC3251/LTC3251-1.2/LTC3251-1.5 ideally suited for space-constrained battery-powered applications. The parts are short-circuit and over-temperature protected, and are available in a thermally enhanced 10-pin MSOP package.


  • Handheld Devices
  • Cellular Phones
  • Portable Electronic Equipment
  • DSP Power Supplies

Features and Benefits

  • 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