A controller for switching power supplies includes a nonlinear controller component capable of providing a duty cycle to a pulse width modulator. The duty cycle corresponds to at least one predetermining switching power supply state variable. A nonlinear controller component receives as inputs at least one predetermined switching power supply state variable. A relationship between duty cycle and at least one predetermined switching power supply state variable is obtained by a predetermined method. The nonlinear controller component comprises memory for access by an application component. The memory includes a data structure stored in memory and a plurality of duty cycles. Each of the plurality of duty cycles has a corresponding at least one predetermined switching power supply state variable. Each duty cycle, when provided to the pulse width modulator of the switching power supply, provides a predetermined switching power supply output.