Pulse width modulated switching power supply circuit with stabilized voltage

Published:2011/4/27 9:05:00 Author:Nicole | Keyword: switching power supply, pulse width modulated | From:SeekIC

As shown, the main technical indicators are as follows: Output voltage: 12V; Output Current: 1A; power consumption <20W; efficiency> 64%; internal resistance <0.075Ω; ripple <15mV; mains voltage: 160 ~ 240V. Inthe figure, full-wave rectifier circuit is composed of 6VDl, 6VD2; 6C3 is the filter capacitor; 6C1, 6C2 areused to undermine the surge current; self-excited multivibrator is composed of 6VT1, 6VT2, 6VT3 and 6R4, 6C9, and the 6VT1 also is the switching tube. When the 12V output voltage decreases for some reason, the base of the error amplification 6VT4 obtained the voltage from the sampling circuit 6R6, 6R11, 6R8 also will be dropped, the collector voltage of 6VT4 rose, the potential base of 6VT3 also increased, the output pulse of the switch adjustment 6VT1 broadened, then the reduced voltage rising again. On the contrary, when the output voltage drops, it will make a reverse adjustment according to the aboveprocess, then keeping the output voltage steady.



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