| 摘要 |
A power supply unit for an electronic device comprises a three-terminal regulator in a high voltage connection line between a high voltage terminal of a DC power supply circuit and a microcomputer for reducing voltage from the high voltage terminal to a lower first voltage. A low voltage connection line between a low voltage terminal of the power supply circuit and the microcomputer is connected to the high voltage connection line at a connection point on output side of the regulator. In standby mode, voltage from the high voltage terminal, set higher than the first voltage, is reduced by the regulator to the first voltage and supplied to the microcomputer. In power-on mode, voltage from the low voltage terminal, set higher than the first voltage, is applied to the connection point so as to inactivate the regulator and supply the voltage from the low voltage terminal to the microcomputer.
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