Current source for LED drivers based on a linear-assisted DC/DC regulator

Abstract

This article presents a proposal of current source based on a linear-assisted DC/DC converter, in which a linear voltage regulator assists a switching DC/DC converter in order to obtain a compact circuit with advantages of both alternatives; i.e., high efficiency (similar to the switching converter), and low output ripple and fast reaction to the load changes (similar to the linear regulator). In order to reduce the power dissipation in the linear regulator, it is considered as an assisted circuit for providing just a little fraction of the load current. Furthermore, this stage provides the required clock signal for the switching counterpart, resulting in reduction of the complexity in the design of the control scheme for the switching converter and a compact topology, especially for on-chip practical implementations, since no output capacitors are required. This last advantage provides the possibility of obtaining goodperformance current-source drivers for LED technology in lighting applications. The implementation and results indicate that the proposed linear-assisted DC/DC regulator-based current source can achieve a notably compacting and higher performance, while consuming less power in comparison to linear alternatives.