| 摘要 |
PURPOSE:To detect a defect such as missing of a high-order bit including an A/D converter sign bit efficiently and surely by comparing a digital data being the result of converting a reference signal with a check code corresponding to me reference signal by an analog/digital(A/D) converter so as to decide the conversion accuracy. CONSTITUTION:A reference voltage source 6 outputting two reference voltages +VR and -VR with equal absolute value and different sign, a check code generator 7 selecting and outputting one of check codes coincident with the result of A/D conversion of the voltages +VR and -VR, and a control circuit 8 applying an output selection control of the check code generator 7 and control of comparison calculation of a comparator 4 in interlocking with the switch control of a multiplexer 1 are provided to the title circuit. Thus, both the cases with '1' of a high-order bit and '0' are confirmed by applying coincidence check as to two reference voltages of noninverting input and inverting input. Thus, the defect of missing bit such as fixed '1's or fixed '0's is detected surely. |
