Abstract: A regulated power supply provides a regulated supply voltage at a preselected level under normal operating conditions. When power demands of the circuitry driven by the supply requires a higher voltage, the supply adapts to supply such a higher voltage. Such a supply can be used with automotive electronic circuitry, and can supply voltages up to approximately the voltage available on an automobile battery when such higher power demands occur. The higher supply voltages remain regulated, and return to normal levels when the extra power requirement is removed.

Abstract: A structure for protecting an integrated circuit against high supply line voltages is formed in an epitaxial silicon layer of one conductivity type on a semiconductor substrate of another conductivity type. A transistor is formed in the epitaxial layer to protect the integrated circuit against low range overvoltages. A highly doped region in the epitaxial layer on one side of the transistor of the same conductivity type as the expitaxial layer extends to the substrate. The highly doped region is connected to a reference potential and establishes a parasitic SCR with the transistor and substrate with a controllable breakover voltage above the protection voltage of the transistor.