CONTROL_FOR_SWITCHING_REGULATOR

Published:2009/7/14 3:19:00 Author:May | From:SeekIC

Uses all four sections of Motorola MC3302 quad comparator. First section is connected as 20-kHz oscillator that supplies sawtooth output sweeping between voltage limits set by 100K positive feedback resistor and 15-V supply. Section 2 compares sawtooth output to feedback signal, to produce variable-duty-cycle output pulse for power switch of switching regulator. Sections 3 and 4 initiate current-limiting action; section 3 senses over current and triggers section 4 connected as mono MVBR. Limiting occurs at about 4 A. When load short is removed, regulator resets automatically. Point A goes to push-pull drive for power switch of regulator, and point B goes to current-sensing resistor in output circuit of regulator. Point y goes to 10-V supply.-R. J. Bayer, A New Approach to Switching Regulators, Motorola, Phoenix, AZ, 1975, AN-719, p 7.



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