The application circuit of pulse width modulated type switching stabilized voltage supply

Published:2011/4/19 4:00:00 Author:May | Keyword: pulse width modulated, switching, stabilized voltage supply | From:SeekIC

In the diagram it is an actual example of pulse width modulated switching regulated power supply. It is Kaige 4D17U type which is produced by Shanghai the fourth radio factory. It is stabilized voltage supply of 35cm black and white TV set. Its main technical target is shown in the following: Output voltage: 12V; Output current: 1A’ Power consumption <20W; Efficiency >64% Internal resistance <0.075Ω; Ripples <15mV; Commercial power voltage: 160~240V. In the diagram, full wave rectification circuit consists of 6VD1, 6VD2; 6C3 is filter capacitor; 6C1, 6C2 is used to slack down surge current; free running multi-vibrator consists of 6VT7, 6VT2, 6VT3 and 6VT4, 6C9. At the same time, 6VT7 is switching tube. When 12V output voltage reduced because of some reasons, the voltage which is got from sample circuit 6R6, 6R9, and 6R8 by error amplifier tube 6VT5 is also reducing. 6VT5’s collector voltage is rising. 6VT3’s base level is rising too. The output pulse of 6VT7 is broadening. Then the reduced voltage is rising again. On the contrary, when output voltage reduced, we can opposite adjust according to this process above mentioned. It can let the output voltage remain stable.



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