An apparatus and method are disclosed for providing efficient operation in a feedback loop having a synchronous buck converter. The synchronous buck converter includes a plurality of individually selectable phases, where each of the phases has a plurality of individually selectable and parallel switching legs. The circuit stores information that associates multiple different load values with respective configuration settings that each define a number of phases and a number of switching legs. As the load changes, the circuit measures the load and selects an appropriate configuration setting. The circuit applies the selected configuration setting to operate the number of phases and a number of parallel switching legs in the buck converter.