256_NEGATIVE_STEPS

Published:2009/7/10 6:01:00 Author:May | From:SeekIC

Interconnection of Exar XR-2240 programmable timer/counter with 741 opamp and precision resistor ladder forms staircase generator. Reset pulse drives output low. When trigger is applied, output goes high and circuit generates negative-going staircase having 256 equal steps. Duration of each step is equal to time-base period as determined by values used for R and C. Staircase is stopped by applying disable signal (less than 1.4V) to pin 14 through steering diode. Supply voltage range is 4-15 V. If counter cannot be triggered when using supply above 7 V and less than 0.1μF for C, connect 300 pF from pin 14 to ground.- Timer Data Book, Exar Integrated Systems, Sunnyvale, GA, 1978, p 11-18.



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