Patent ID: 7777556
Filing Date: 2010-08-17
Classification: G06F

Abstract:
1. A semiconductor integrated circuit comprising: a first power supply having first potential controlled under control operation from an external control circuit; a second power supply having second potential controlled under control operation from the external control circuit, and the second potential being set independently of the first power supply; a first power-supply system comprising a circuit driven by the first power supply; a second power-supply system comprising a circuit driven by the second power supply; and a connecting circuit performing connecting operation between a first high-potential line of the first power-supply system and a second high-potential line of the second power-supply system in response to a potential-matching signal indicating that the first power-supply system and the second power-supply system are operated by the same potential from the external control circuit, wherein the connecting circuit comprises: a pulse circuit receiving the potential-matching signal and a clock signal, and outputting a first pulse signal; a monitoring circuit monitoring the ground potential of the first power-supply system or the second power-supply system during a pulse period of the first pulse signal, and outputting a second pulse signal having a second-pulse period corresponding to a changing period of the ground potential; and a switch receiving the second pulse signal to a gate terminal thereof and connects the first high-potential line of the first power-supply system to the second high-potential line of the second power-supply system during the second-pulse period of the second pulse signal.