A circuit for supplying a DC output of a desired voltage from an input
regardless of power received. In this circuit, a rectifier converts an
alternating current (AC) input to direct current (DC) or changes a DC
input to a desired polarity. A boost converter receives DC current having
a first voltage from the rectifier and outputs DC current having at least
a minimal voltage. Finally, a buck boost converter receives the DC current
having at least the minimal voltage and outputs DC having a desired
voltage.