Switching voltage regulator of Jinxin brand TV

Published:2011/11/14 3:33:00 Author:May | Keyword: Switching voltage regulator, Jinxin brand TV | From:SeekIC

Switching power supply with input and output isolation normally has three forms: transformer isolation, photoelectric coupling isolation and sampling and output segregating isolation. Switching voltage regulator of Jinxing brand is shown in the diagram. It adopts two transformers. Sampling circuit R1, Rp and R2 directly connect to the output end of power supply. It can sample from 120V output voltage to a scale and add to the base of error amplifier VT1. This voltage and the reference voltage offered by VD1 and R5 are compared and enlarged by VT1. Then the collector is outputting error voltage. It is direct coupled by R7 and giving it to pulse width modulation circuit composed of Schmidt trigger VT2 and VT3. Then it is changed to pulse. The pulse is enlarged by VT4. It can realize total isolation except switching output stage. Its sound insulation is perfect. What’s more, we should use a transformer T1.



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