Control circuits are provided for regulating an output voltage of a switched mode power supply having a variable input voltage and at least one power switch. The control circuits are operable to generate a comparison voltage based on the output voltage of the switched mode power supply and a duty cycle of a control signal provided to the at least one power switch, determine a reference voltage based on whether the generated comparison voltage falls within one of a plurality of voltage ranges, and adjust the duty cycle of the control signal provided to the at least one power switch of the switched mode power supply as a function of the determined reference voltage and the output voltage. Each voltage range is associated with a different reference voltage. Switched mode power supplies including the control circuits and methods implemented by the control circuits are also disclosed.