Abstract: Input and output switching transistors are alternatively activated to form a charging path and a discharging path for an inductor. The inductor periodically charges through the input transistor from an unregulated rechargeable battery, and discharges through the output transistor into an output capacitor. The output voltage taken across the output capacitor is regulated by negative feedback which varies the inductor charging period through the input transistor. The converter regulation is bidirectional. The voltage from the battery is initially greater than the regulated output voltage, but decreases to a value less than the output voltage as the battery discharges. When the battery is fully charged the converter regulates the battery voltage down to the output voltage. As the battery voltage drops through discharge, the converter regulates the lower battery voltage up to the output voltage.