A method for controlling a DC-to-DC converter includes: (a) regulating a magnitude of an output voltage of the DC-to-DC converter according to a magnitude of a reference voltage; (b) in response to a command to enter the unregulated operating mode, allowing the magnitude of the output voltage to fall; and (c) adjusting the magnitude of the reference voltage to track the magnitude of the output voltage. A controller for a DC-to-DC converter includes reference and switching modules. The reference module generates a reference voltage, such that: (a) a magnitude of the reference voltage is fixed, in a regulated operating mode, and (b) the magnitude of the reference voltage tracks a magnitude of an output voltage of the DC-to-DC converter, in the unregulated operating mode. The switching module controls a power stage of the DC-to-DC converter to regulate the magnitude of the output voltage, in the regulated operating mode.