| 摘要 |
PURPOSE:To simplify the constitution of a response detecting circuit and to prevent mis-detection by inputting an output signal of a current supervising circuit so as to discriminate a threshold value of positive/negative amplitude, incrementing/decrementing a counter means and detecting the response through this count value. CONSTITUTION:A DOWN input of a counter circuit 105 makes count by taking precedence over a UP input. When an input voltage (c) is applied to an input line 13, an output represented by (d) is obtained at an output of a comparator 103 and an output represented by (e) is obtained at an output of a comparator 104. On the other hand, the input to an input line 21 is the result of supervision of a DC feeding circuit, and a signal having the probability of mis-detection as shown in (f). Thus, the input line 21 is connected to an OR circuit 102 together with an output of the comparator 103, an output (g) is obtained and inputted to the UP input of the counter circuit 105. The result QN of the count is inputted to a discriminating circuit 106, and when the value is larger than a judged threshold value TH, the response detection output is outputted.
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