Implementation of a DC/DC Converter with Stepwise Charge and Improved Battery Lifetime

An integrated buck-boost DC/DC converter for interfacing battery sources to capacitive loads such as supercapacitors is presented. The converter features a current regulation circuit on the source side, which applies a predefined constant DC current to the battery source, thus preventing the application of sharp current pulses generally associated with conventional DC/DC switching activity and resulting in long-term battery degradation. In fact, flat current shaping positively affects lifetime of battery sources. A specific digital control technique is proposed, which guarantees low energy losses during conversion by implementing a stepwise pseudo-adiabatic energy transfer that limits the maximum current inside the circuit and reduces the damping effect on current oscillation due to resistive paths.