Patent ID: 7868684
Filing Date: 2011-01-11
Classification: H02M

Abstract:
1. A semiconductor device whose internal power supply voltage is generated by a voltage step-up circuit that comprises: a first capacitor coupled between a first node and a second node; a second capacitor coupled between a third node and a fourth node; a first switch disposed between the first node and the third node; a second switch disposed between the second node and the fourth node; a third switch disposed between the second node and the third node; a first terminal connected to the first node; a second terminal connected to the second node; a third terminal connected to the fourth node; a fourth switch disposed between the fourth node and the third terminal; a first voltage detection circuit that detects a voltage at the second terminal and compares the voltage with a first predetermined reference voltage; a second voltage detection circuit that detects a voltage at the third terminal and compares the voltage with a second predetermined reference voltage; and a switch control circuit that receives detection signals detected by the first voltage detection circuit and the second voltage detection circuit and controls the first switch, the second switch, the third switch and the fourth switch; wherein the switch control circuit controls the first switch and the second switch to be in a conducting state and controls the third switch and the fourth switch to be in a non-conducting state if a condition is satisfied that a voltage at the second terminal is lower than a first predetermined reference voltage and a voltage at a third terminal is higher than a second predetermined reference voltage; and, when a predetermined pulse signal is input to the first terminal, the first capacitor and the second capacitor output a first stepped-up voltage to the second terminal.