Patent ID: 6686782
Filing Date: 2004-02-03
Classification: G01R,H03K

Abstract:
A power supply voltage detection circuit for outputting a signal upon detecting that a power supply voltage, which is a potential difference between a first power supply and a second power supply, is equal to or higher than a predetermined first voltage, the power supply voltage detection circuit comprising:a voltage division circuit for linearly dividing the power supply voltage, which is the potential difference between the first power supply and the second power supply, so as to output a signal of an output voltage, which is a voltage at the division point with respect to the second power supply; a reference voltage circuit for outputting a signal of a reference voltage, which is defined to be equal to the output voltage from the voltage division circuit when the power supply voltage is equal to the first voltage; a comparison circuit for comparing an input voltage, which is a voltage of the output voltage signal received from the voltage division circuit, with the reference voltage of the reference voltage signal received from reference voltage circuit; and signal cancellation means, having a predetermined second voltage, for canceling an input of the output voltage signal from the voltage division circuit to the comparison circuit when the power supply voltage is lower than the second voltage, while not canceling the input of the output voltage signal when the power supply voltage is higher than the second voltage.