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Buck-boost converter suits GSM modems

Posted: 23 Feb 2010 ?? ?Print Version ?Bookmark and Share

Keywords:buck-boost converter? supercapacitor? GSM modem?

From Linear Technology Corp. comes a 96 percent efficient, synchronous buck-boost converter that delivers up to 1A 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 200mA to 1000mA range, making it suitable 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, significantly improving data rates or charging times. The LTC3127's input range of 1.8V to 5.5V and output range of 1.8V to 5.25V 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 excellent performance. The LTC3127's constant 1.35MHz switching frequency offers low noise operation while minimizing the size of the few required external components. The combination of tiny externals and a 3mm x 3mm DFN or MSOP-12 package provides a highly compact solution footprint for space-limited applications.

The LTC3127 includes two n-channel MOSFETs (140m? and 160m?, respectively) and two p-channel MOSFETs (160m? and 190m?, respectively) to deliver efficiencies of up to 96 percent. The device's selectable Burst Mode operation requires only 35?A of quiescent current and shutdown current is less than 1?A, 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.

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 respectively, each, for 1,000-piece quantities.

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