A switching regulator controller for a buck switching regulator incorporates a multi-mode adaptive modulator configured to automatically select between a first operation mode and a second operation mode as a function of the output voltage being generated. In one embodiment, the switching regulator controller compares the output voltage to a comparator reference voltage and is configured to operate in a selected operation mode based on the output voltage. In this manner, a single switching regulator controller can be used in multiple instances of an electronic system to supply circuitry that may have different operational requirements. In one embodiment, the switching regulator controller is configured to operation in a PWM/PFM mode and a PWM mode as a function of the output voltage, which indicates the circuit application to which the switch regulator controller is used to supply.