| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply circuit having an excellent constant voltage characteristic and capable of reducing heat generation. SOLUTION: The power supply circuit 23 is provided with a constant voltage circuit 31 having a high response speed, a constant voltage circuit 32 having high efficiency even when an output current is large and a voltage detection circuit 34 for detecting the output voltage of the circuit 32. The circuit 23 is also provided with a circuit 33, D21, D23 for switching both the constant voltage circuits 31, 32 by a detection output S34 from the circuit 34 and a capacitor C22 for storing the output voltage of the circuits 31, 32. The constant voltage circuits 31, 32 are switched so that output voltage V31 from the circuit 31 is supplied to loads 21, 22 when a load current is small and the output voltage of the circuit 32 is supplied to the loads 21, 22 when the load current is large.
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