| 摘要 |
PURPOSE:To exactly detect the malfunction of a counter circuit and to improve the reliability by providing plural sequence logic circuits for counting separately the same input signal with each different circuit constitution, and a comparator. CONSTITUTION:In the counter circuit which consists of sequence logic circuits 111-11n and a comparator 12, and is constituted so as to fetch a counting output from a prescribed sequence logic circuit, the circuits 111-11n have each different circuit constitution, and count separately the same input signal, respectively. Also, the circuit 12 compares each output signal of the circuits 111-11n, and outputs a malfunction detecting signal, based on the result of its comparison. Accordingly, even if the circuit is mounted onto the same printed board or the same chip, and consequently, the operation environments become similar to each other, probability in which the malfunction is caused simultaneously can be made extremely small. That is, the malfunction of the counter circuit can be detected exactly, and also, the reliability can be improved without forming the circuit on a large scale. |
