1A_WITH_0005_VOLTAGE_ACCURACY

Published:2009/7/8 23:26:00 Author:May | From:SeekIC

Use of National LM120 negative regulator with LM108A low-drift opamp and 1N829 precision reference diode gives extremely tight regula-tion, very low temperature drift, and full over load protection. Bridge arrangement sets output voltage and holds reference diode current constant. FET is required because 4-mA maximum ground current of regulator exceeds output current rating of opamp. R1 and R2 should track to 1 PPM or less. R3 is chosen to set reference current at 7.5 mA. For output of 8 to 14 V, use LM120-5.0; for 15-17V, use LM120-12.-C. T. Nelson, Power Distribution and Regulation Can Be Simple, Cheap and Rugged, EDNMagazine, Feb. 20, 1973, p 52-58.



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