Stromversorgungssystem für elektrische Kreise mit verschiedenen Betriebsspannungen

摘要

An electric power supply system distributes power voltage levels to electric circuits (C1 to Cn) different in operating voltage from one another, and comprises a plurality of step-down units (DW1 to DWn-1) each coupled between two of the electric circuits, wherein each of the plurality of step-down units comprises a first step-down transistor (Q11) having an emitter-and-collector current path coupled between the associated two electric circuits, and a second step-down transistor (Q12) having an emitter-and-collector current path between one of the associated two electric circuit and another step-down unit so that part of current from one of the associated two electric circuits is reused in the other of the associated two electric circuits.