| 摘要 |
Provided is a power supply switching circuit with a smaller circuit scale. When a detector (11) detects that a voltage (V1) as an input power supply voltage is higher than a detection voltage (VDET), a control circuit (41) operates with a voltage (V4) output from a diode OR circuit (42), supplies a voltage (V2) as an input power supply voltage to a gate of a PMOS transistor (17), supplies a voltage (V3) to a gate of a PMOS transistor (18), and supplies a ground voltage to a gate of a PMOS transistor (19). Then, the PMOS transistors (17 and 18) are turned OFF and the PMOS transistor (19) is turned ON. In this case, the voltage V1 of a first terminal (T1) is output from a third terminal (T3) as the voltage (V3), which is an output power supply voltage.
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