7V, 500mA Synchronous Buck-Boost DC/DC Converter Provides Extended Battery Run Time in Handheld Applications

Feb 24 2009 - MILPITAS, CA
  • Linear Technology announces the LTC3534, a 7V synchronous buck-boost converter that can delivers up to 500mA of output current to a regulated output above, below or equal to the input using a single inductor. The device's topology provides a continuous transfer through all operating modes making it ideal for three- or four- cell Alkaline/NiCad/NiMH or single cell lithium applications which must maintain a constant output voltage even as the battery voltage declines below the output. A typical application is alkaline cells with an input voltage range of 3.6V to 6.4V, powering a 5V output rail. In most cases this Buck-Boost DC/DC Converter can add up to 25% more battery run-time compared to a traditional SEPIC solution. The LTC3534's constant 1MHz switching frequency ensures low noise while minimizing the size of external components. The combination of tiny externals and a 3mm × 5mm DFN (or SSOP-16) provide a tiny solution footprint, typically required in handheld applications.

    The LTC3534 includes two N-Channel MOSFETs and two P-Channel MOSFETs (215mΩ/275mΩ and 260mΩ, respectively) to deliver efficiencies of up to 94%. Burst Mode® operation requires only 25µA of quiescent current while shutdown current is less than 1µA, further extending battery run-time. If the application is noise sensitive, the PWM pin can also be configured to provide forced continuous operation to reduce noise and RF interference. Other features include soft-start, current limiting, thermal shutdown and output disconnect.

    LTC3534EDD is available from stock in a 16-lead 3mm ×5mm DFN package, and the LTC3534EGN is available in a 16-lead SSOP package. Pricing for both versions is $3.15 each in 1,000 piece quantities. For more information, visit www.linear.com.

    Summary of Features: LTC3534

    • Regulated Output with Input Voltages Above, Below or Equal to the Output
    • 2.4V to 7V Input & 1.8V to 7V Output Voltage Ranges
    • 5V VOUT at 500mA from 4 AA Cells
    • Single Inductor
    • Synchronous Rectification: Up to 94% Efficiency
    • Burst Mode® Operation with 25µA IQ
    • Output Disconnect in Shutdown
    • 1MHz Switching Frequency
    • <1µA Shutdown Current
    • Small Thermally Enhanced 16-Lead (3mm × 5mm × 0.75mm) DFN & 16-Lead SSOP Packages

    7V Buck-Boost Synchronous DC/DC Offers Extended Battery Run-Time


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