Abstract: A digitally controlled switchmode power supply by the use of a pulse width modulated (PWM) controlled field effect transistor, switches an inductor between input and output sides to provide a controllable DC output voltage. The digital processor receives and digitizes the input and output voltages and also the current through the associated inductor and derives a PWM control loop signal driving the associated field effect switching device to switch the inductor. The foregoing compensates for nonlinear changes in the value of the inductance due to changes in inductor currents and also avoids resonance at pole points of the LC circuit in the power supply. In addition a change in buck to boost modes may be accomplished automatically depending on input voltage operating conditions.