Abstract: A bootstrap circuit that operates in combination with switchmode DC to DC converter topologies that are based on forward (10), half-bridge/full-bridge (40) and flyback (60) configurations. Each configuration consists of an output circuit (18) and a bootstrap modified input circuit (12) that further consists of a bootstrap circuit (14) and a converter input circuit (16). The bootstrap function is achieved by charging a bootstrap inductor (L1) from current derived from the input voltage source and subsequently discharging the inductor through a bootstrap capacitor (C1) where an augmented voltage that is higher than the input voltage is developed. The converter then operates from the augmented voltage rather than from the input voltage. Thus, the invention is able to provide a constant output when operated over a wide-input voltage range while at the same time reducing the voltage stresses on the converter's primary switches and output rectifiers.