LONG_TIME_TIMER

Published:2009/7/8 2:49:00 Author:May | From:SeekIC

When used as a stand-alone device, ZN1034E from Ferranti can provide timed intervals ranging from 1 second to 19 days, although the rc time constant is only 220 seconds. The ZN1034E includes an internal voltage regulator, an oscillator, and a 12-stage binary counter. The total delay time prodded by the counter is 4095 times the oscillator period. The control logic times-out after 4095 cycles of the oscillator, and delivers high and low output pulses at pins 2 and 3. The output at pin 3 is normally high and decreases at the end of the timed interval. The complementary output at pin 2 is normally low and becomes high at the end of the timed interval. The timing period is initiated by momentarily grounding pin 1. Timing resistor RT consists of two resistors, R1 and R2, in series. Because R1 has a fixed value of 100 KO, the total range of ;RT 100 K to 1.1 MΩ.



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