OPAMP_DRIVESLED

Published:2009/7/1 23:19:00 Author:May | From:SeekIC

LM301A is used as open-Ioop voltage comparator, with LED receiving total source current of about 20 mA from opamp. Input is TTL-compatible, with R1-R2 reference divider biasing opamp in center of TTL output transition region. Circuit realizes full open-loop speed of opamp since it is uncompensated and its internal voltage amplifier stages are kept out of saturation by clamping of D2 and by inherent current-limiting action. Response times for toggling LED are in microsecond range.-W. G. Jung, Poor Man's LED Driver is TTL Compatible, EDN Magazine, Feb.5, 1973, p 86.



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