Patent ID: 7009537

Claim:
An apparatus for detecting an A/D converter abnormality comprising: an A/D converter having input terminals of one or more channels for inputting analog signal voltages and a capacitor for sample-holding the analog signal voltages, and for AD-converting the analog signal voltages sample-held in the capacitor into digital signal values; input means for inputting analog signals to the input terminals of at least one channel, a signal operation voltage range being limited to be narrower than a range of input operation voltages of the A/D converter when the analog signals are normal; a storage means storing in advance an abnormality determining range of the digital signal values converted by the A/D converter; voltage range setting means for setting the abnormality determining range to values corresponding to a voltage range in an input voltage range of the A/D converter outside the limited range of signal operation voltages; means for detecting an A/D converter abnormality to determine an A/D conversion to be abnormal when a value of a digital signal converted from the limited analog signal lies in the abnormality determining range; and initializing means for initializing the voltage accumulated in the capacitor by a last A/D conversion operation into a voltage that lies within the abnormality determining range at least prior to sample-holding the limited analog input signal voltage in the capacitor.