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Internal Composition Of The Power Adapter
Sep 18, 2018

       The power adapter replaces the position of the linear power supply with high efficiency, low power consumption, small size, light weight, light weight, convenient carrying, strong anti-interference and wide output voltage range. The power adapter is mainly controlled by the control circuit. Rectifier filter, integrated circuit, power switch tube, protection circuit, output rectifier filter, switching power supply transformer, input grid filter and other components.

       1. Control circuit: detect the output DC voltage, compare it with the reference voltage, amplify, modulate the pulse width of the oscillator, and thus control the converter to keep the output voltage stable. The general power adapter output voltage adjustment rate is 5%.


       2. Input rectifier filter: rectify and filter the 220V or 110V AC voltage input by the grid to provide DC voltage to the converter. For example, the rectifier bridge functions to convert the AC power into DC power, and the filter capacitor acts to filter out the DC power. AC ripple makes the circuit work more reliable.


       3, integrated circuit (op amp IC), protection circuit, an important part of voltage regulation.


       4. Power switch tube: The power switch tube is one of the core components in the switching power supply. The switch tube alternates in the positive feedback and negative feedback circuits, the positive feedback is responsible for conduction, and the negative feedback is responsible for the cutoff.


       5. Protection circuit: If overcurrent, overvoltage, overpower, and short circuit occur, the protection circuit stops the power adapter to protect the appliance and the power adapter itself from damage. For example, the varistor in the protection current, the varistor principle When the external voltage is too high, the resistance of the varistor quickly becomes very small. At this time, the resistance of the varistor is reduced to shunt the current to prevent excessive transient voltage damage or interference, thus protecting other circuits from being protected. damage.


       6. Output rectifier filter: The high-frequency AC voltage output from the converter is rectified and filtered to obtain the required DC voltage, and also prevents the interference of high-frequency noise on the load. For example, the filter capacitor filters the ripple in the low-voltage DC. .


       7. Switching power supply transformer: The switching power supply transformer is a power supply transformer that has been added to the switching tube. In addition to the voltage conversion function of the ordinary transformer, the circuit also has the functions of insulation isolation and power transmission, which are generally used in switching power supplies and other fields involving high frequency circuits. .


       8. Input grid filter: Eliminate interference from the power grid, such as motor start, electrical switch, lightning strike, etc., and also prevent high-frequency noise generated by the switching power supply from spreading to the grid. Such as inductor coil (also known as choke) The main function is to reduce electromagnetic interference.