| 摘要 |
PURPOSE:To detect a peak value by allowing a comparator to decide on variation of an input signal converted into a digital signal. CONSTITUTION:The input signal is passed through an A/D converter 6 and compared by the comparator 7 with the output of a latch 8. When the input signal is larger than the past peak value, the input signal is latched and when smaller, the past peak value is held as it is. Therefore, the comparator 7 outputs logic ''1'' when the input signal exceeds the past peak value and the value of the latch circuit 8 is also updated. When the input signal decreases after exceeding the peak value, its large/small relation with the last signal held in the latch 8 is inverted and the comparator 7 outputs logic ''0'' to detect the peak point. A D/A converter 9 is connected to the output of the latch 8 and the peak value is detected from an analog voltage. The latch 8 continues to hold the value after maximum voltage detection, so the output variation of the D/A converter 9 becomes less and it is reset with a digital signal, so there is not any problem such as a reset switch breakdown due to a large current.
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