| 摘要 |
A power switching circuit is provided to prevent power loss due to a parasitic bipolar transistor by preventing formation of a current path due to a parasitic diode. A first power source(102) is connected to a first power terminal. A second power source(103) is connected to a second power terminal. A drain of a first MOS transistor(106) is connected to the first power terminal. A source of the first MOS transistor is connected to a load terminal. A drain of a second MOS transistor(107) is connected to the first power terminal. A source of the second MOS transistor is connected to the load terminal. A first power detecting circuit detects connection of the first power source in the first power terminal, and outputs a detecting signal. A control circuit(113) outputs a control signal to a gate of the first MOS transistor and the second MOS transistor according to the detecting signal. A boost circuit(114) boosts the first power source or the second power source, and outputs a boosting voltage. A first level shifter(108) and a second level shifter(109) shift the control signal into the boosting voltage.
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