Auto-Polarity, Millivolt Voltage Step-Up Converter & Power Manager

Linear Technology Corp. announced the LTC3109, a highly integratedstep-up dc/dc converter and power management IC designed to start up and runfrom millivolt input voltage sources such as thermoelectric generators (TEGs)and thermopiles. The device's groundbreaking and proprietary auto-polaritytopology allows it to generate usable power from input voltages as low as plus or minus 30mV, enabling temperature differences as low as plus or minus 1C to be harvested in lieuof traditional battery power. This makes it ideal for energy harvestingapplications in which the input voltage polarity is unknown or is subject toreversal. Energy harvesters are well suited for applications requiring lowaverage power, even with periodic pulses of higher load current. For example,in many wireless sensor applications the circuitry is only powered to takemeasurements and transmit data periodically with a low duty cycle.

The LTC3109 uses two standard compact step-uptransformers to provide a complete power management solution. Its 2.2V LDO canpower an external microcontroller, and its main output is pin selectable to oneof four (2.35, 3.3, 4.1 or 5V) fixed voltages to power a sensor, dataacquisition circuits and/or a wireless transmitter. A second switched outputcan be enabled by the host in order to power devices that do not have amicropower shutdown capability. The addition of a storage capacitor providescontinuous power even when the input energy source is unavailable orintermittent. The LTC3109's extremely low quiescent current (less than 7muA) andhigh efficiency design ensure the fastest possible charge times for the outputreservoir capacitor. The combination of the LTC3109's leadless 4mm x 4mm QFN-20package (or leaded SSOP-20) and very small external components ensure a highlycompact solution for energy harvesting applications.

The LTC3109EUF is available in a 20-lead 4mmx 4mm QFN package and the LTC3109EGN is available in a SSOP-20 package. Pricingstarts at $3.95 each for 1,000-piece quantities. Industrial temperature gradeversions, the LTC3109IUF and LTC3109IGN, are also available, priced starting at$4.65 each for 1,000-piece quantities. All versions are available from stock.

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