Patent ID: 8635472
Filing Date: 2014-01-21
Classification: G06K

Abstract:
1. A semiconductor integrated circuit device comprising: an antenna terminal coupled to an antenna; a power supply terminal which receives power supplied from outside of the semiconductor integrated circuit device; a first power supply circuit coupled to the antenna terminal and which provides a voltage to a power supply line; a switch transistor coupled between the power supply terminal and the power supply line; a detection circuit operable to detect a source of power supplied from the power supply terminal or the first power supply circuit; a substrate control circuit operable to control a substrate voltage of the switch transistor; and a power control circuit coupled to a gate of the switch transistor, and which is configured to be controlled by the detection circuit, wherein when the detection circuit detects a source of power supplied from the power supply terminal, the power control circuit controls the switch transistor to suppress voltages supplied from the power supply terminal to a predetermined voltage and outputs the resultant voltage to the power supply line, and the substrate control circuit provides a power supply from the power supply terminal to the substrate voltage of the switch transistor, and wherein when the detection circuit detects a source of power being supplied from the power supply line coupled to the first power supply circuit, the switch transistor is set to an OFF state, and the substrate control circuit provides power supplied from the power supply line to the substrate voltage of the switch transistor.