PROBLEM TO BE SOLVED: To provide an input signal erroneous determination prevention circuit of simple circuitry, in which a microcomputer prevents erroneous determination of the state of a switch according to an inputted signal.SOLUTION: An input signal erroneous determination prevention circuit 10 includes a comparison circuit 11 for comparing the power supply voltage V of a power supply 3 with a voltage threshold L, and outputting a voltage drop signal Sa when the power supply voltage V goes below the voltage threshold L, a holding circuit 12 receiving a voltage signal S1 continuously from a switch 5, and when receiving the voltage drop signal Sa outputted from the comparison circuit 11, holding the voltage signal S1, received before receiving the voltage drop signal Sa, as a holding signal S2, and a changeover circuit 13 for receiving the voltage signal S1 and the holding signal S2, outputting the voltage signal S1 to a microcomputer 2 when the power supply voltage is normal, and outputting the holding signal S2 to the microcomputer 2 during when power supply voltage drop when the voltage drop signal Sa is outputted.SELECTED DRAWING: Figure 2
【課題】回路構成が簡単であり、且つ、マイクロコンピュータが入力した信号に応じてスイッチの状態を誤判定することを防止する入力信号誤判定防止回路を提供すること。【解決手段】入力信号誤判定防止回路10は、電源3の電源電圧Vと電圧閾値Lとを比較し、電源電圧Vが電圧閾値L未満となった場合に電圧低下信号Saを出力する比較回路11と、電圧信号S1をスイッチ5から連続的に入力しており、比較回路11から出力された電圧低下信号Saを入力したとき、電圧低下信号Saを入力する前に入力した電圧信号S1を保持信号S2として保持する保持回路12と、電圧信号S1及び保持信号S2を入力し、電源電圧正常時においては電圧信号S1をマイクロコンピュータ2に出力し、電圧低下信号Saが出力された電源電圧低下時においては保持信号S2をマイクロコンピュータ2に出力する切替回路13と、を備える。【選択図】図2
INPUT SIGNAL ERRONEOUS DETERMINATION PREVENTION CIRCUIT
入力信号誤判定防止回路
2018-08-23
Patent
Electronic Resource
Japanese
European Patent Office | 2020
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