Up-down voltage regulator

摘要

An up-down voltage regulator includes an up regulator followed by a series pass PNP transistor. The base of the PNP transistor is coupled to an unregulated voltage source. The up regulator is responsive to the voltage at the collector of the PNP transistor to control the emitter voltage of the PNP transistor for all values of the unregulated voltage source to bias the PNP transistor so as to establish and maintain the collector voltage of the PNP transistor at a desired regulated value.