Patent ID: 7683591

Claim:
A semiconductor device, comprising: a capacitance element having one end connected to a power supply, the capacitance element for detecting a voltage variation of the power supply; a first comparator having two input nodes having opposite polarities to each other, a first input node of the two input nodes for receiving a reference voltage and a second input node of the two input nodes connected to an output of the other end of the capacitance element to compare the respective voltage values to output a first output signal indicating a comparison result, such that the capacitance element is connected in series with the power supply and the second input node; a first resistor element connecting the first input node and the second input node of the first comparator; a second resistor element having a first end directly connected to said power supply; a third resistor element having a first end connected to a second end of the second resistor and having a second end directly connected to a ground terminal; a second comparator having two input nodes directly connected to the first end of the third resistor element and the reference voltage terminal, respectively, and for outputting a second output signal indicating a second comparison result; a logic OR circuit which performs a logic OR operation of the first output signal of the first comparator and the second output signal of the second comparator; and a reset circuit for receiving an output signal of the logic OR circuit, and for halting operation of a system including the semiconductor device when the output signal of the OR circuit is activated; wherein the first comparator is for outputting a first output signal indicating the comparison result when a predetermined voltage difference exists between the inputted reference voltage and the inputted output of the other end of the capacitance element.