Programmable DC-DC Converter Suits GSM, GPRS Apps

Jan 6, 2009 1:01 PM, MD&D News Staff

The 1.6-MHz LTC3125 current-mode, synchronous boost dc-dc converter from Linear Technology enables users to program the average input current limit between 200 and 1000 mA with ±5% accuracy. Its internal 1.2-A switches can deliver output voltages as high as 5.25 V from an input voltage range of 1.8 to 5.5 V. This makes the LTC3125 well-suited for Li-ion/polymer, 3.3-V PC-card slot or multi-cell alkaline/NiMH applications. The converter can deliver up to 500 mA of continuous output current at 5.25 V from a 3.3-V input.

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The accurate adjustable current limit combined with an output reservoir capacitor suits the LTC3125 for applications such as GSM and GPRS cards, which demand 2-A or higher current pulses from a power-limited input source. In addition, the accurate input current enables safe and fast charging of large supercapacitors or ultracapacitors in battery backup systems without overstressing the battery or auxiliary power source.

Synchronous rectification enables efficiencies up to 93% while Burst Mode operation lowers quiescent current to only 15 μA, 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- by 3-mm DFN-8 package and a constant switching frequency of 1.6 MHz minimizes both inductor and capacitor sizes, providing the tiny footprint and profile required in PC-card applications. Additional features include short-circuit protection, soft-start, and thermal protection.

The LTC3125EDCB is available from stock. Pricing in 1000-piece quantities starts at $2.25 each.