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Linear Tech 800mA Synchronous Buck-Boost DC/DC Converter

Linear Technology Press Release FlashlightNews.org - 7/30/2007

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Converter Offers Extended Battery Run Time for Battery Powered Handhelds


Typical Application: LTC3538 - 800mA Synchronous Buck-Boost DC/DC Converter

Typical Application: LTC3538 - 800mA Synchronous Buck-Boost DC/DC Converter

MILPITAS, Ca. - Linear Technology announces the LTC3538,a synchronous buck-boost converter that can deliver a regulated output voltage at up to 800mA of continuous current with an input voltage above, below or equal to the output. Its input range of 2.4V to 5.5V and output range of 1.5V to 5.25 makes it ideal for single cell Li-Ion/Polymer applications.

The LTC3538 provides a smooth continuous transfer through all of the operating modes, making it ideal for applications that must maintain a constant output voltage even as the battery voltage declines below the output. In Li-Ion/polymer-powered applications that require 3.3V outputs, such as miniature hard disk drives and DSP I/O power, this unique buck-boost design provides over 25% more battery run-time.

The LTC3538ís constant 1MHz switching frequency ensures low noise while minimizing external component size. The combination of tiny externals and a 2mm x 3mm DFN package provide the tiny solution footprint required in handheld applications.

The LTC3538 includes two N-Channel MOSFETs and two P-Channel MOSFETs (0.17 Ohm and 0.20 Ohm, respectively) to deliver efficiencies of up to 96%. Burst Mode® operation requires only 35µA of quiescent current while shutdown current is less than 1µA to further extend battery run-time. Other features include soft-start, current limiting, thermal shutdown and output disconnect in shutdown.

LTC3538EDCB is available from stock in a 2mm x 3mm 8-lead DFN package. Pricing is $2.65 each in 1,000 piece quantities.

Summary of Features: LTC3538

  • Regulated Output with Input Voltages Above, Below, or Equal to the Output
  • Up to 96% Efficiency
  • 800mA Continuous Output Current from a Single Lithium-Ion/Polymer Cell
  • Single Inductor
  • 1MHz Fixed Frequency Operation
  • Output Disconnect in Shutdown
  • 2.4V to 5.5V Input
  • 35µA Quiescent Current in Burst Mode Operation, <5µA Shutdown Current
  • Internal Soft-Start
  • Small, Thermally Enhanced 8-Lead (2mm x 3mm) DFN package










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