What is the working principle of the power switch?
What is the working principle of switching power supply?
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Switching power supply is used to control the switch through the circuit for high-speed pass and cut off.
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The conversion of direct current into high-frequency alternating current is provided to the transformer for transformer, resulting in the required group or groups of voltages! Turn to high frequency pay
The reason for the flow is the high frequency AC in the transformer transformer circuit efficiency than
50HZ
Much higher. So the switch transformer can be done very small, and
Work is not very hot!
But we also note that 300V DC power added to the standby power switch and standby power switch transformer, the standby power switch is designed to self-excited oscillation mode, standby power switch immediately start working in the standby power switch transformer times Level output two sets of AC voltage, the rectifier filter, the output + 5VSB and +22 V voltage, +22 V voltage is designed for power supply internal control IC power supply. + 5VSB voltage for the standby voltage, the output to the motherboard. When the user presses the power button of the chassis, the motherboard sends a power-on signal to the power supply. At this time, the (green) color line is low, the IC's internal oscillation circuit starts immediately, generates the pulse signal, The signal is applied to the base of the main switch tube by pushing the transformer so that the main switch is operated in the high frequency switching state. The main switch transformer output voltage of each group, after rectification, filtering and regulation, get each group of DC voltage, the output to the computer host. But the CPU on the motherboard at this time has not yet started, must wait + 5V voltage from zero to 95%, IC detection +5 V rose to 4.75V, IC issued P.G signal, the CPU starts, the computer work properly. When the user shuts down, the green line is at a high level, the IC immediately stops oscillating, the main switch tube because there is no pulse signal and stop working. -12 to +3.3 of the voltage drop to zero. The power supply is in standby mode.
Protection circuit principle brief:
In the normal use of the process, when the IC detects the load is in: short circuit, overcurrent, overvoltage, undervoltage, overload and other state, IC internal signal, so that the internal oscillation stopped, the main switch tube because there is no pulse and stop working The So as to achieve the purpose of protecting the power supply.
Working Principle:
220V AC through the first and second EMI filter into a more pure 50Hz AC, the full bridge rectifier and filter output 300V DC voltage. 300V DC voltage at the same time added to the main switch, the main switch transformer, standby power switch, standby power switch transformer. As the main switch at this time there is no switch signal, in the cut-off state, so the main power switch transformer no voltage output, the figure of -12V to +3.3 V, 5 groups of voltage are no voltage output.
