LED Colorful Display Switch Power Supply Part

- Aug 27, 2017-

                100v~240v, 50hz~60hz alternating current degaussing resistor PTH1 to the degaussing coil L103 power to eliminate screen magnetism. Alternating current by the bridge reactor BD101 Rectifier, the high-voltage DC, pulse wide-wave modulation (PWM) integrated circuit IC101 (UC3842) ⑥ foot output pulse width modulation signal to the high back voltage power field effect tube Q101, the modulated currents through the switch transformer T101 output three-way power supply.LED Colorful Display

                The first route D108 and D109 provide the output pipe Q405 power supply to the row of the 100V high voltage power supply, and the low voltage mode is controlled by IC201 ⑦ Q103, Q102 conduction, so that the output voltage is increased to compensate for the extra consumption of the scan frequency change. The second way is provided by D110 20V and ED201 to provide 12V with different low-voltage power supplies. The third way is to IC101 the required power supply. In the boot of the moment by the High-voltage R106 start circuit, switching transformers after work, by the D103 continue to provide power.LED Colorful Display

                 IC101 internal pressure protection, undervoltage stop circuit. ①, ② in the foot of the error amplifier, R113 is the amplifier feedback resistance, the greater the resistance, the higher the sensitivity of the amplifier. ③ foot internal for the current detection comparator, ⑧ foot for the 5V regulator source, ④ the outside of the foot connected R, C components determine the pulse width modulation oscillator frequency. The working voltage of the IC101 shall not exceed 30V. Switching power supply feedback loop has two ways: all the way through the flow protection sampling resistance R104, when the leakage current of the Q101 is too large, the voltage on the R104 passes through the R102 to the Ic101③ pin to reduce the pulse width duty ratio of the ⑥ foot, in order to reduce the output power, and the other way the error amplifier is sent by D112, and the output power can also be changed. The oscillation frequency of IC101 can also be synchronized with the line scan frequency, which provides the line frequency pulse signal by a turn cord around the T403 core of the output transformer, so when the output level of the line is working, the operating frequency of the switching power supply is synchronized with the line frequency locking.LED Colorful Display

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