Patent ID: 7956789

Claim:
A disconnection detecting circuit, comprising: a sample-and-hold capacitor that stores an electric charge which is input from an input terminal; a full charge section that fully charges the sample-and-hold capacitor; a discharge section that discharges the sample-and-hold capacitor; an analog-to-digital (A/D) conversion section that converts an analog signal indicative of a potential of the sample-and-hold capacitor into a digital signal; a storage circuit section that stores a conversion result from the A/D conversion section; an A/D conversion control section that controls the full charge of the sample-and-hold capacitor by the full charge section with an input from the input terminal, controls the discharge of the sample-and-hold capacitor by the discharge section, and stores A/D conversion results of the potential of the sample-and-hold capacitor before and after discharge in the storage circuit section; a comparison section that compares the A/D conversion results before and after discharge, which are stored in the storage circuit section; a difference determination section that detects a difference between the potentials before and after discharge on the basis of a comparison result by the comparison section; and a control section that determines that the input terminal is abnormal when the difference determination section determines that there is the difference.