Patent ID: 8604821

Claim:
A power supply voltage monitoring circuit for monitoring a power supply voltage supplied to an electronic circuit, comprising: a signal output circuit for outputting a signal voltage which exhibits a saturation characteristic with respect to an increase in the power supply voltage, wherein the signal output circuit outputs, when power is turned on, a signal voltage which increases along with an increase in the power supply voltage until the power supply voltage makes a transition to a predetermined voltage, and outputs a voltage which monotonously increases and has a saturation characteristic in a case where the power supply voltage continues to increase after exceeding the predetermined voltage; and a signal voltage monitoring circuit for comparing the power supply voltage with the signal voltage, and for outputting a signal indicating that the signal voltage is normal when there is a predetermined voltage difference between the power supply voltage and the signal voltage; wherein, the signal voltage monitoring circuit compares the signal voltage output from the signal output circuit with the power supply voltage, and outputs a signal indicating that the power supply voltage has exceeded a minimum operating power supply voltage of the electronic circuit when there is the predetermined voltage difference between the power supply voltage and the signal voltage.