A charging circuit includes an interface connector that may be coupled to a power adapter that provides an input voltage, and a buck-boost charging circuit that receives the input voltage and may be coupled to and may provide an output signal to a battery having a charging voltage. For a given input voltage and a given charging voltage, the buck-boost charging circuit operates in one of a group of modes based on a control signal, where the group of modes comprises: a buck mode, a boost mode and a buck-boost mode. In particular, the charging circuit includes control logic that generates the control signal based on the charging voltage and the input voltage. Thus, the buck-boost charging circuit may operate over a continuous range of input voltages and charging voltages.