400mA Synchronous Step-Up dc/dc Converter

Linear Technology'sLTC3105, a highperformance, synchronous boost converter incorporates maximum power pointcontrol (MPPC) and starts up with inputs as low as 250mV. The LTC3105 operatesover an input range of 0.2 to 5V, making it useful for harvesting energy fromhigh impedance alternative power sources, including photovoltaic cells,thermoelectric generators (TEGs) and fuel cells. The LTC3105's internal 400mAsynchronous switches maximize efficiency while its Burst Mode^A(R)operation offers quiescent current of only 22uA, further optimizing converterefficiency overall operating conditions. A user-programmable MPPC set pointmaximizes the energy that can be extracted from any power source withoutcollapsing its internal voltage.

The LTC3105 is useful to power wireless sensors and data acquisitionapplications. Surplus or ambient energy can be harvested and then used togenerate system power in lieu of traditional wired or battery power, which maybe expensive or impractical. Typically, these applications require very lowaverage power, but require periodic pulses of higher load current. For example,the LTC3105 can be used in wireless sensor applications where the power load isextremely low when the sensor is in standby mode, interrupted by periodic highload bursts, when the circuitry is powered up to take measurements and transmitdata.

The LTC3105 offers an auxiliary LDO that delivers up to 6mA of output current topower external microcontrollers and sensors while the main output is charging.Once fully charged, the main output can deliver voltages as high as 5.25V withup to 100mA of output current. It can also regulate VOUT even when V_INis greater than or equal to V_OUT, offering further designflexibility. In shutdown, the LTC3105 offers output disconnect, isolating V_INfrom V_OUT, requiring only 4uA of quiescent current.

The LTC3105EDD is available in a 10-lead 3 x 3mm DFN package and the LTC3105EMS isavailable in an MSOP-12 package. Prices start at $2.70 each for 1,000-piecequantities. Both are available from stock.

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