DC_CONTROL_BY_TTL_I_O

Published:2009/7/6 20:55:00 Author:May | From:SeekIC

Output of microprocessor drives LED of photocoupler through one section of 7414 hex Sch mitt-trigger-input inverter. Phototransistor switches power transistor or power Darlington on and off for control of direct current through load. With transistor having current gain of 30 and 20-mAcontrol cur-rent, load current can be 500 mA. With power Darlington having higher current gain, load can be several amperes. Since power de-vice is either off or saturated, heatsink can be small.-M. Boyd, Interfacing Tips, Kilobaud, Feb. 1978, p 72-74.



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