A Family of Multimodes Charge Pump based DC–DC Converter With High Efficiency over Wide Input and Output Range

Abstract

A family of multimodes charge-pump-based two-stage wide input or output range dc-dc converter is proposed for large step-down or step-up applications. The proposed converter contains a multimodes charge pump and a cascaded synchronous buck or boost converter. The charge pump is unregulated and it may be implemented as the prestage in step-down application or as the poststage in step-up application. Moreover, it may adaptively switch between 1×, 0.5×, and 0.33× modes according to the input voltage in step-down case; or switch between 1×, 2×, and 3× modes according to the output requirement in the step-up case. For both cases, the charge pump does the rough voltage conversion, while the buck/boost converter does the fine voltage regulation. Since the charge pump converter and the buck/boost converter exhibit different efficiency tendency when the input or output changes, the total efficiency can get improved by combining them, especially at high input voltage for step-down case or low voltage for step-up case. In this paper, theoretical efficiency analysis and comparisons show the multimode charge-pump-based two-stage solution has superior performance over the traditional single-stage buck/boost solutions. Moreover, the two-stage solution of wide input range dc-dc converter brings benefits to the control loop design and as a result, the bandwidth variation is restrained and the compensator design is simplified. Detailed efficiency analysis with loss breakdown is presented and the performance of the proposed two-stage solution is verified by the designed prototypes.