Electronicdesign 7506 0625npdtltc

Nanopower DC-DC Features Energy-Harvesting Battery Charger

June 26, 2014
Linear Technology’s LTC3331 delivers up to 50 mA of continuous output current to extend battery life when harvesting energy is available.

Linear Technology’s LTC3331 delivers up to 50 mA of continuous output current to extend battery life when harvesting energy is available. Thanks to a simple 10-mA shunt, a rechargeable battery with harvested energy can be charged while a low-battery disconnect function protects the battery from deep discharge. The device needs a mere 200 nA of supply current from the battery when providing regulated power to the load from harvested energy, and only 950 nA when powered from the battery under no-load conditions. Integrated into the LTC3331 are a high-voltage energy-harvesting power supply, battery charger, and synchronous buck-boost dc-dc converter powered by a rechargeable battery. The power supply consists of a full-wave bridge rectifier accommodating ac or dc inputs and a high-efficiency buck converter. It harvests energy from piezoelectric (ac), solar (dc), or magnetic (ac) sources. When harvested energy is unavailable, the rechargeable battery input powers a buck-boost converter that operates over the full battery-voltage range up to 4.2 V (the LTC3331 automatically transitions to the battery when the harvesting source is no longer available). Energy-harvesting inputs operate from 3 to 19 V ac or dc. Undervoltage lockout threshold settings are programmable between 3 and 18 V. Packaging is a 5- by 5-mm QFN.

LINEAR TECHNOLOGY CORP.

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