| 摘要 |
PURPOSE:To set voltage without being limited by another power terminal when the potential of a plurality of power terminals is set. CONSTITUTION:A power-supply selector circuit has resistors R1-R4 connected to a plurality of power terminals Y1, V2, a comparator 1 comparing outputs from these resistors R1-R4, inverters 2, 3 waveform-shaping an output from the comparator 1, P-type MOS transistors 4, 6 tuned on/off by outputs from these inverters 2, 3, and diodes 5, 7 feeding voltage when these P-type MOS transistors 4, 6 are not turned on. The potential of each power terminal V1, V2 is compared by the comparator 1, and the power terminal having highest potential as the result of the comparison is used as an output power supply V0. Accordingly, an interface between functional blocks operated at the potential of each power terminal V1, V2 is conducted at the potential, and the set potential of each power terminal V1, V2 is not limited by other power terminals. |
