| 摘要 |
In a switching circuit, a first input terminal and a second input terminal are connected to an output terminal by switching transistors which are selectively activated to supply the desired input signal to the output terminal. In order to output selectively, a voltage detector detects a level of a first input voltage at the first input terminal so that either the first switching transistor or the second switching transistor turns on. The voltage at the output terminal is controlled by a voltage controlling circuit in accordance with the stability of the output signal. The voltage controlling circuit does this by controlling the conducting state of the first switching transistor so that a stable output voltage can be obtained. Since the voltage controlling circuit drives the gate of the first switching transistor, it may be a small device operable with low consuming current, thereby the chip size can be reduced.
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