Session T4A: Tutorial: Tiny DC-sourced single inductor charge-supply ICs

A challenge wireless micro-sensors and other microsystems face is short lifetime, because tiny batteries store little energy. Although miniaturized fuel cells and atomic sources store more energy than lithium ions and super capacitors, they source less power, so they cannot power as many functions. Unfortunately, their power-dense counterparts cannot sustain life for long. Thankfully, the environment also holds vast amounts of energy, and of typical sources, like light, motion, temperature, and radiation, sunlight produces the highest power density, but only when available. The fact is, combining miniaturized fuel or photovoltaic cells with tiny lithium-ion batteries or super capacitors can be more compact, reliable, and longer lasting than any single technology. Managing a hybrid system of this sort to supply a microwatt application, however, requires an intelligent, low-loss dc-dc power converter. This talk discusses the state of the art in miniaturized charger-supply systems that draw power from an energy-dense dc source and supplementary power from a battery to supply a load and recharge the battery with excess power from the energy-dense source.