Patent ID: 6359474
Filing Date: 2002-03-19
Classification: H03K

Abstract:
An input interface circuit comprising:a comparator that compares a potential level of a signal input from a signal input terminal with a threshold value and that outputs a comparison result via a signal output terminal; a detector that detects a power supply potential supplied to the comparator; and a controller that controls the threshold value of the comparator based on the detected power supply potential, wherein the comparator includes a first conductive type first transistor having one end connected to a first power supply line, another end connected to the signal output terminal, and a control terminal connected to the signal input terminal, and a second conductive type second transistor having one end connected to a second power supply line, another end coupled to the signal output terminal and a control terminal connected to the signal input terminal, and wherein the controller includes a resistance circuit that connects the first power supply line to the signal output terminal when a predetermined potential is detected by the detector and the first transistor is on, wherein the resistance circuit includes a first conductive type third transistor, disposed between the first power supply line and the signal output terminal, having a control terminal connected to the signal input terminal, and a fourth transistor, connected to the third transistor in series, having a control terminal at which the detected power supply potential is input thereto.