Patent ID: 7782124
Filing Date: 2010-08-24
Classification: H03K

Abstract:
1. A semiconductor device, comprising: a voltage supply circuit comprising: an n-channel MOS transistor, the drain of which is connected to a power supply, the source of which is connected to a channel of the n-channel MOS transistor, wherein a voltage of the gate of the n-channel MOS transistor is controlled so that the n-channel MOS transistor is in an on-state during an operation and is in a cut-off condition in a standby; and an p-channel MOS transistor, the source of which is connected to the source of the n-channel MOS transistor, and the drain of which is connected to a load, wherein when being on standby, for an output voltage supplied from the drain of the p-channel MOS transistor to the load to be a grounding potential, a voltage equivalent to or higher than a power supply voltage is applied to the gate of the p-channel MOS transistor so that a gate-source voltage of the p-channel MOS transistor, higher than the gate-source voltage of the p-channel MOS transistor between the gate and source under a cut-off condition of the p-channel MOS transistor, is applied between the gate and source of the p-channel MOS transistor, wherein when a voltage is applied to the load, a grounding potential is supplied to the gate of the p-channel MOS transistor so as to set the p-channel MOS transistor to be in the on-state and a voltage equivalent to or higher than the power supply voltage is supplied to the gate of the n-channel MOS transistor so as to set the n-channel MOS transistor to be in the on-state, wherein, when being on standby, the voltage equivalent to or higher than the power supply voltage is applied to the gate of the p-channel MOS transistor and the grounding potential or a negative potential is applied to the gate of the n-channel MOS transistor and the gate-source voltage of the p-channel MOS transistor, higher than the voltage between the gate and source of the p-channel MOS transistor under the cut-off condition, is applied so that the absolute value of the difference in voltage between the gate-source voltage of the p-channel MOS transistor when said transistor is turned on and the gate-source voltage of the p-channel MOS transistor when said transistor is turned off is larger than the absolute value of the difference in voltage between the gate-source voltage when said p-channel MOS transistor is turned on and the gate-source voltage when said p-channel MOS transistor is turned off based on a cut-off condition.