Control multiplexor for a switch mode power supply

Abstract

A digital circuit directs operation of a pulse width modulation or pulse frequency modulation controller varying its control between closed loop and open loop topology. An exemplary control plant could embody a step-down switch mode power supply providing a precise sequence of voltages or currents to any of a variety of loads such as the core voltage of a semiconductor unique compared to its input/output ring voltage. A state machine monitors pulse width or pulse frequency from the pulse width modulation or pulse frequency modulation controller, respectively, while either type of controller operates in its closed loop topology, to determine if the present power state of the system matches the predicted load as characterized from a predetermined model used in conjunction with design automation tools. The state machine averages pulse widths or pulse frequencies monitored in the closed loop topology. If the average deviates from the predicted pulse width or pulse frequency for the present power state, the state machine updates a corresponding value in a table of pulse width or pulse frequency values from which an open loop controller applying pulse width modulation or pulse frequency modulation, respectively, generates a near critical damped step response during system power state transitions or maintains a maximally flat voltage during system current transients.