Brief description of working principle:
After the first and second EMI filtering, 220V AC becomes a purest 50Hz AC, and output 300V DC voltage after full bridge rectification and filtering. The 300V DC voltage is simultaneously added to the main switching tube, main switching transformer, standby power switching tube and standby power switching transformer.
1. The fourth foot is current detection, the current is large off the output 2. The seventh foot is voltage feedback, which can control the output duty cycle, the lower the voltage duty cycle, the smaller the voltage, generally controlled by the optocoupler output, the optocoupler input is the post-stage voltage input, which is generally composed of TL431 or voltage regulator tubes, and some are also composed of comparators