An integrated ultracapacitor fast mains charger with combined power/current optimisation

This paper presents a novel integrated self-oscillating step-down converter for the fast charging of stacks of large ultracapacitors from a 230V AC mains source. The charger architecture controls both power and current to optimise the charge rate with respect to the limitations imposed by the mains source and the capacitors themselves. The circuit has been fabricated in a 0.35μm bulk medium voltage CMOS, process.