Semiconductor integrared circuit

A semiconductor integrated circuit comprising:

• a micro-controller having at least two electronic circuits;
• a power supervisory circuit for supervising a power supply voltage of externally provided main power source and backup capacitor;
• a first power supply terminal connected to the main power source;
• a second power supply terminal connected to the backup capacitor;
• a first power supply line connecting a first electronic circuit of said micro-controller and said first power supply terminal;
• and
• a second power supply line connecting a second electronic circuit of said micro-controller and said second power supply terminal,
• wherein said power supervisory circuit being supplied with main power from said main power source through and first power supply terminal, and supplied with backup power from said backup capacitor through said second power supply terminal, and said power supervisory circuit including,
• a first switch that connects/disconnects said first and second power supply lines with each other;
• a second switch that connects said second power supply terminal to said first power supply terminal or said second power supply line;
• a third switch that connects/disconnects said first power supply terminal and said first power supply line with each other;
• and
• a control circuit which monitors said main power source, and provides controls over said first, second, and third switches, wherein
• when said main power source is normal, said control circuit controls said first and third switches so that said first and second electronic circuits are driven by power from said main power source, and controls said second switch so that said second power supply terminal is connected to said first power supply terminal, thereby driving said first and second electronic circuits by power from said main power source;
• and
• when said main power source has a failure, said control circuit controls said first switch so that said first and second power supply lines are connected with each other, controls said second switch so that said second power supply terminal is connected to said second power supply line side, and controls said third switch so that connection between said first power supply terminal and said first power supply line is not established, thereby driving said first and second electronic circuits by power from said backup capacitor.