WINDOW_DETECTOR_1

Published:2009/7/14 23:05:00 Author:Jessie | From:SeekIC

Unique voltage-range sensing circuit provides positive indications of high, low or acceptable input levels for voltage and includes adjustments for both threshold and hysteresis levels. R1 and R2 ad just upper and lower thresholds, while R3 and R4 adjust upper and lower hysteresis levels. If acceptable input range is 4.5 V to 5.5V, output of opamp A1 goes negative when ein is greater than 5.5V. This saturates Q1 and Q2, making Q2 output go from 5 V to 0. TTL then indicates that input has exceeded 5,5 V. Upper hysteresis keeps A1 output negative until input has dropped to setting of R3, which might be 5.3 V. Similarly, when input drops below 4.5 V, output of A2 goes positive and saturates Q3.-I. KrellAnalogMonitor Has Threshold and Hysteresis Controls, EDN Magazine, Aug.1, 1972, p 58.



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