Abstract: A pulse-width controller for a switching regulator is provided. The pulse-width controller is coupled to a bulk regulator in the switching regulator to control the bulk regulator to produce an output voltage in a fixed level and an output current in a desired level in response to various demands from the load. The pulse-width controller takes a voltage of feedback-voltage indicative of a change in the output voltage of the bulk regulator and a first voltage of feedback-current and a second voltage of feedback-current indicative of a change in the output current of the bulk regulator as feedback signals. These feedback signals can cause the pulse-width controller to produce a square-wave signal with an adaptive pulse width that controls the bulk regulator to produce the output voltage and current in the desired levels.