Thursday, June 25, 2009

DC/DC Converter For GSM And GPRS Cards

Linear Technology has announced the LTC3125, a 1.6MHz current mode, synchronous boost DC/DC converter with an accurate and programmable average input current limit. Its internal 1.2A switches can deliver output voltages as high as 5.25V from an input voltage range of 1.8V to 5.5V, making it ideal for Li-ion/polymer, 3.3V PC card slot or multi-cell alkaline/Nimh applications.

The LTC3125 can deliver up to 500mA of continuous output current (at 5V) from a 3.3V input. The LTC3125's average input current limit can be programmed between 200mA and 1000mA with +/- 5 per cent accuracy. The accurate adjustable current limit combined with an output reservoir capacitor makes the LTC3125 ideal for applications such as GSM and GPRS cards, which demand 2A or higher current pulses from a power-limited input source. In addition, the LTC3125's accurate input current enables safe and fast charging of large super- or ultra-capacitors in battery backup systems without overstressing the battery or auxiliary power source.

Synchronous rectification enables efficiencies up to 93 per cent while burst mode operation lowers quiescent current to only 15uA, providing extended battery runtime in handheld applications. The LTC3125 can also operate in Buck mode, providing a regulated output lower than the input. The combination of a 2 x 3mm DFN-8 package and a constant switching frequency of 1.6MHz minimise both inductor and capacitor sizes, providing the small footprint and profile required by PC-card applications. Additional features include short-circuit protection, soft-start, and thermal protection. LTC3125EDCB is available from stock in an eight-lead 2 x 3mm DFN package.

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