Discontinuous conduction mode pulse-width modulation

A method for regulating an output voltage in a power regulator system, the method comprising:

• comparing an error voltage that is associated with an output voltage of the power regulator system with a fixed-frequency ramp signal;
• controlling a PWM control signal to have an activation pulse-width for activating a high-side switch that is based on the comparison;
• activating the high-side switch at an edge-trigger of the PWM control signal to couple a power voltage to an inductor to generate the output voltage;
• switching the power regulator system from a continuous conduction mode (CCM) to a discontinuous conduction mode (DCM) in response to detecting approximately zero current flow through the inductor;
• and
• reducing the error voltage from a first magnitude to a second magnitude in response to switching the power regulator system from the CCM to the DCM, the difference between the first and second magnitudes being proportional to the output voltage.

A power regulator system comprising:

• means for generating an output voltage across a load based on a high-side switch coupling a power voltage to an inductor at an edge-trigger of a PWM control signal having a duty-cycle that defines an activation pulse-width of the high-side switch;
• means for switching the power regulator between a continuous conduction mode (CCM) and a discontinuous conduction mode (DCM) based on a magnitude of a current through the inductor;
• means for setting the activation pulse-width of the PWM control signal in the CCM based on a magnitude of an error voltage associated with the output voltage relative to a fixed-frequency ramp signal;
• and
• means for setting the activation pulse-width of the PWM control signal in the DCM based on a magnitude of the output voltage relative to the power voltage.