Buck-boost converter for space-critical tasks
Linear Technology
LTC3127 buck-boost converter
The LTC3127 from Linear Technology is a 96 per cent efficient, synchronous buck-boost converter that is ideal for GSM modems or supercapacitor chargers.
The LTC3127 is said to deliver up to 1A of output current to a regulated output voltage with inputs above, below or equal to the output.
It features a +/- 4 per cent accurate programmable average input current limit with a 200mA to 1,000mA range, making it ideal for GSM modems or supercapacitor chargers powered from sources with hard limits on output current.
This enables system designers to maximise the current draw from a limited power source, 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.
Its current mode buck-boost topology provides a continuous transfer mode through all operating modes, simplifying design and ensuring good performance.
The LTC3127's constant 1.35MHz switching frequency offers low-noise operation while minimising the size of the few required external components.
The combination of tiny externals and a 3 x 3mm DFN or MSOP-12 package is said to provide a highly compact solution footprint for space-limited applications.
The LTC3127 includes two N-channel Mosfets (140mohm and 160mohm, respectively) and two P-channel Mosfets (160mohm and 190mohm, respectively) to deliver efficiencies of up to 96 per cent.
The device's selectable burst mode operation requires only 35uA of quiescent current and shutdown current is less than 1uA, 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.
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