| 摘要 |
PROBLEM TO BE SOLVED: To provide a power source switching circuit that is capable of switching a power source without an influence of variations in manufacture and changes in the external environment, and of operating reliably with less variation in the output voltage at the time of power source switching. SOLUTION: The circuit has a first input terminal 1, a second input terminal 2, and one output terminal 5, and the configuration of a constant-voltage circuit 10 arranged between the first input terminal 1 and the output terminal 5 is of series regulators. The circuit has a switching means 6 that can control the state of continuity between the second input terminal 2 and the output terminal 5. When the power source of the second input terminal 2 is selected, the series regulator operates at a lower set voltage lower than the voltage of the output terminal 5. When the power source of the first input terminal 1 is selected, the regulator returns to an arbitrary set voltage higher than the lower set voltage, and a delay circuit 11 operates only when a switching means 8 is shut off. COPYRIGHT: (C)2005,JPO&NCIPI
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