96 percent efficient buck-boost converter delivers maximum current from limited power sources

Linear Technology has released a 96 percent efficient, synchronous buck-boost converter that delivers up to 1 A of output current to a regulated output voltage with inputs above, below or equal to the output.

The LTC3127 features a ±4 percent accurate programmable average input current limit with a 200 mA to 1000 mA range, making it ideal for GSM modems or Supercapacitor chargers powered from sources with hard limits on output current. This enables system designers to maximize the current draw from a limited power source, improving data rates or charging times. The LTC3127's input range of 1.8 V to 5.5 V and output range of 1.8 V to 5.25 V is compatible with all types of PC card slots, USB and single-cell Li-Ion or dual/triple-cell alkaline/NiCd/NiMH applications.

The LTC3127's current mode Buck-Boost topology provides a continuous transfer mode through all operating modes a simplifying design, and ensuring performance. The LTC3127's constant 1.35 MHz switching frequency offers low noise operation while minimizing the size of the few required external components. The combination of tiny externals and a 3 mm x 3 mm DFN or MSOP-12 package provides a highly compact solution footprint for space-limited applications.

The LTC3127 includes two N-channel MOSFETs (140 mOhm and 160 mOhm, respectively) and two P-channel MOSFETs (160 mOhm and 190 mOhm, respectively) to deliver efficiencies of up to 96 percent. The device's selectable Burst Mode operation requires only 35 μA of quiescent current and shutdown current is less than 1 μA, further extending battery run time. For applications requiring the lowest possible noise, the LTC3127 can be configured to run in fixed frequency PWM mode, reducing noise and potential RF interference. Other features include thermal overload protection and output disconnect.

Summary of Features: LTC3127

  • Programmable (0.2A to 1 A) ±4 percent Accurate Average Input Current Limit
  • Regulated Output with Input Voltages Above, Below or Equal to Output
  • 1.8 V to 5.5 V (Input) and 1.8 V to 5.25 V (Output) Voltage Range
  • 0.6 A Continuous Output Current: VIN > 1.8 V
  • 1 A Continuous Output Current: VIN > 3 V
  • Single Inductor
  • Synchronous Rectification: Up to 96 percent Efficiency
  • Burst Mode Operation: IQ = 35 μA (Pin Selectable)
  • Output Disconnect in Shutdown

  • <1 μA Shutdown Current
  • Small, Thermally Enhanced 10-Lead (3 mm x 3 mm x 0.75 mm) DFN and 12-Lead MSOP Packages

Availability and Pricing

The LTC3127EDD is available from stock in a 10-lead DFN package and the LTC3127EMSE is available in a 12-lead thermally enhanced MSOP package. Pricing is $2.95 and $3.00 respectively, each, for 1,000-piece quantities.



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