Patent ID: 7423472
Filing Date: 2008-09-09
Classification: H03K

Abstract:
1. A power switching circuit, comprising: a first p-type transistor and a second p-type transistor connected in series between a first power source and a second power source; a gate control circuit having a first power supply terminal connected to the first power source, a second power supply terminal connected to the second power source, a control signal terminal to which a control signal is input, a first output terminal connected to the gate of the first P-type transistor, and a second output terminal connected to the gate of the second P-type transistor; and a well-potential control circuit having a first power supply terminal connected to the first power source, a second power supply terminal connected to the second power source, and an output terminal connected to the well of the first P-type transistor and the well of the second P-type transistor; wherein the gate control circuit outputs a voltage equal to that of the first power source to the first output terminal and outputs a voltage equal to that of the second power source to the second output terminal when the control signal is in a low level, and outputs an earth potential to the first output terminal and the second output terminal when the control signal is in a high level, and wherein the well-potential control circuit outputs the voltage equal to that of the first power source to the output terminal when the voltage of the first power source is higher than that of the second power source, and outputs the voltage equal to that of the second power source to the output terminal when the voltage of the second power source is higher than that of the first power source.