Patent ID: 7952400
Filing Date: 2011-05-31
Classification: H03K

Abstract:
1. A reset device for outputting a reset signal based on a magnitude of an input power supply voltage, comprising: a power supply voltage monitoring unit including a comparator to which a detection voltage detected at a first point in a voltage divider circuit based on the magnitude of the power supply voltage and a reference voltage to be used as an inversion reference for the reset signal are input, the comparator comparing the detection voltage with the reference voltage and outputting an output voltage in accordance with a result of the comparison from an output terminal; an N-channel MOS transistor setting a threshold voltage for generating the reset signal having hysteresis, the gate of the N-channel MOS transistor being connected to the output terminal of the comparator, the drain of the N-channel MOS transistor being connected to a second point in the divider circuit, and the source of the N-channel MOS transistor being connected to a ground line, wherein the second point is closer to the ground line than the first point; and a reset signal outputting unit outputting the reset signal, the reset signal outputting unit including a first inverter to which the output voltage output from the power supply voltage monitoring unit is input and a second inverter disposed and connected to the first inverter in series as continuous stages, each of the first inverter and the second inverter including a P-channel MOS transistor and an N-channel MOS transistor, wherein the first inverter includes a first resistor disposed at one of between a source of the P-channel MOS transistor and a power supply voltage line and between a source of the N-channel MOS transistor included in the first inverter and a ground line, and the second inverter includes a second resistor disposed at one of between a source of the P-channel MOS transistor and a power supply voltage line and between a source of the N-channel MOS transistor and a ground line,