The LTC3109 from Linear Technology is a highly integrated DC/DC converter specifically designed for energy harvesting applications. It can operate from ultra-low input voltages as low as 30mV, utilizing a unique, proprietary auto-polarity architecture to function regardless of input polarity. The component is ideal for harvesting energy from thermoelectric generators (TEGs) and thermopiles, efficiently converting this energy to power remote sensors, wireless transmitters, and low-power devices. Key features include selectable output voltages of 2.35V, 3.3V, 4.1V, or 5V, a 2.2V low-dropout (LDO) regulator, a logic-controlled output, and an energy storage system to maintain operation during power interruptions. The LTC3109 is encapsulated in a small, 20-lead (4mm × 4mm) QFN or SSOP package, making it compact and suitable for space-constrained applications in HVAC systems, building automation, and industrial wireless sensing. Additionally, the power good indicator and the ability to use compact step-up transformers further enhance its suitability for low power, energy-harvesting systems.