DC/DC converter runs from TEGs and thermopiles

The LTC3109 is a step-up DC/DC converter and power-management IC that is designed to start up and run from millivolt input voltage sources such as thermoelectric generators (TEGs) and thermopiles.

The device's proprietary auto-polarity topology allows it to generate usable power from input voltages as low as +/-30mV, enabling temperature differences as low as +/-1C to be harvested in lieu of traditional battery power.

This makes it ideal for energy-harvesting applications in which the input voltage polarity is unknown or is subject to reversal.

The LTC3109 uses two standard compact step-up transformers to provide a complete power-management solution.

Its 2.2V LDO can power an external microcontroller and its main output is pin selectable to one of four (2.35, 3.3, 4.1 or 5V) fixed voltages to power a sensor, data-acquisition circuits and/or a wireless transmitter.

A second switched output can be enabled by the host in order to power devices that do not have a micropower shutdown capability.

A storage capacitor provides continuous power, even when the input energy source is unavailable or intermittent.

The LTC3109's low quiescent current of less than 7uA and high-efficiency design ensure the fastest possible charge times for the output reservoir capacitor.

The combination of the LTC3109's leadless 4 x 4mm QFN-20 package (or leaded SSOP-20) and very small external components ensure a highly compact solution for energy-harvesting applications.

The LTC3109EUF is available in a 20-lead 4 x 4mm QFN package and the LTC3109EGN is available in a SSOP-20 package.

Industrial temperature grade versions, the LTC3109IUF and LTC3109IGN, are also available.

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