PURPOSE: To count a long time with an oscillator only with small capacitance of a capacitor, by counting the number of times of repetition of a saw-tooth wave.
CONSTITUTION: When an input signal IN is applied from an input terminal 7, a counter 26 is reset. The output of an inverter 27 is inverted to H level. A voltage V1 is increased in accordance with the constant of a time constant circuit 2. When the voltage V1 reaches a reference voltage, the output of a level detector 3 is inverted to H level. As a result, a flip-flop 20 is set. Thus, a driving circuit 5 is turned on and the output S of the level detector 3 goes immediately to L level. Then, the flip-flop 20 is again inverted to reset state. Thus, the number of pulse signals generated with the flip-flop 20 is counted at the counter 26. When the count reaches a set value, the output pulse is generated.
NISHIJIMA HIDEO
FUKUSHIMA ISAO
GOTOU KATSUHIKO
TEJIMA TSUNEHIKO
