Energy-harvesting buck/boost DC/DC starts from 300 mV

December 15, 2015 // By Graham Prophet
LTC3106 is a highly integrated, 1.6 µA quiescent current, 300mV start-up buck-boost DC/DC converter with Linear’s PowerPath management, intended for multisource, low power systems. The LTC3106 powers low power wireless sensors from rechargeable or primary batteries supplemented by energy harvesting.

The device incorporates maximum power point control (MPPC) making it compatible with common high impedance power sources, including photovoltaic cells, thermoelectric generators (TEGs) and fuel cells. LTC3106 operates over an input voltage range of 300 mV to 5.5V from the primary power source when a backup source, typically a battery, is present. It is compatible with both primary and rechargeable batteries connected to the backup power input. Without a backup source, it operates from 850 mV to 5.5V and down to 300 mV after start-up. If the primary power source is unavailable, the LTC3106 seamlessly switches to the backup power source. The primary power source, which can be derived from harvested energy, can optionally trickle charge the battery whenever surplus energy is available as well as providing power to the load.

The LTC3106 provides 300 mA steady state and 650 mA peak load current at up to 92% efficiency. Its Burst Mode operation offers a quiescent current of only 1.6 µA, optimising converter efficiency over all operating conditions. Zero power “shelf mode” ensures that the backup battery will remain charged if left connected to the LTC3106 for an extended time. An accurate RUN pin and a dedicated MPP pin are provided for input voltage control. Either can be user programmed to set the input source MPP, maximising the energy that can be extracted from the input source. The LTC3106 is suitable for powering wireless sensors and data acquisition applications. Surplus or ambient energy can be harvested and then used to supplement or replace traditional wired or battery power, resulting in significant periodic maintenance cost savings for the user. Typically, such applications, including wireless sensors, require very low average power, but require periodic pulses of higher load current. For example for transmission bursts.

Additional features include a 90 mA peak current limit setting for lower power applications, user-selectable overvoltage and undervoltage protection for a rechargeable battery, thermal shutdown, preset selectable output