Five new power management ICs from Texas Instruments efficiently acquire and manage microwatts (uW) to milliwatts (mW) of power harvested from light, heat or mechanical energy sources. The bq25570, bq25505, TPS62740, TPS62737 and TPS62736 maintain what TI claims are the industry's lowest levels of active quiescent current and enable battery-free operation to wireless sensor networks, monitoring systems, wearable medical devices, mobile accessories, and other applications with limited access to power.
TI's new bq25570 boost charger with integrated buck converter consumes a miniscule 488 nanoamps (nA) of quiescent current and achieves greater than 90-percent efficiency at output currents lower than 10 microamps (uA), maintaining high efficiency even at the lowest amount of available power. The device features maximum power point tracking (MPPT) to extract and manage power from photovoltaic cells and thermoelectric generators, and supports any energy storage element, such as a rechargeable Li-Ion battery, thin film battery, super-capacitor or conventional capacitor. During long periods of storage, power to the bq25570 can be disabled through a “ship mode” feature, which allows the device to consume less than 5 nA.
The bq25505 boost charger is similar to the bq25570, but achieves an even lower active quiescent current of 325 nA. The bq25505 features a unique, autonomous power multiplexor gate drive that enables seamless system operation from energy harvesting sources and the primary battery, ensuring constant power is available when the system needs to operate, even when no energy is available from the harvester.