A voltage regulator operable as a voltage follower while a fusible link is closed and in a regulated voltage mode when the fusible link becomes open. The voltage regulator can be formed on monolithic semiconductor chips. Patterned thin films including aluminum and nickel-iron, and aluminum and polycrystalline silicon, comprise the fusible link. With the fusible link closed, the voltage regulator output is an analog of positive polarity variable voltage levels at the regulator input. Systems powered by the voltage regulator are allowed to be programmed until system programming requiring variable voltage levels is complete. Afterwards, a negative polarity voltage is applied to the regulator input causing a large current to pass through the fusible link once the system programming is completed. Current thereby causes the fusible link to become opened and enables the voltage regulator to begin operating at a regulated voltage in response to positive voltage input.