Semiconductor integrated circuit

摘要

A semiconductor integrated circuit includes two power supply lines and at least one electronic circuit connected to each of the power supply lines. One of the two power supply lines is connected with an externally located main power source, and the other power supply line is connected with an externally located backup power source. A switch electrically connects or disconnects the power supply lines with each other. A power supervisory circuit monitors voltage of the main power source and controls the switch. The switch is controlled so that power from the main power source is supplied to the electronic circuits when the main power source is operating normally, and power from the backup power source is supplied to the electronic circuits when the main power source has a failure.