A mode-transition architecture for USB controllers is described herein. In an example embodiment, an integrated circuit (IC) controller includes a controller coupled to a slope compensation circuit, the controller to detect a transition of a buck-boost converter from a first mode having a first duty cycle to a second mode having a second duty cycle that is less or more than the first duty cycle. The controller controls the slope compensation circuit to nullify an error in an output caused by the transition. The controller can cause the slope compensation circuit to apply a charge stored in a capacitor during a first cycle to start a second cycle with a higher voltage than the first cycle.