Classification and principle of power adapter

Issue Time:2006-11-06
First, the principle of the power adapter:
The power adapter mainly includes a power frequency transformer, an output rectifier filter, a control circuit, a protection circuit, and the like. The linear power supply first converts the alternating current through the transformer and then rectifies and filters through the rectifier circuit to obtain an unsteady DC voltage. To achieve high-precision DC voltage, the output voltage must be adjusted by voltage feedback. This power supply technology is very mature and can reach very much. High stability, low ripple, and no interference and noise from the switching power supply.

However, its shortcoming is that it requires a large and bulky transformer. The required filter capacitor has a large volume and weight, and the voltage feedback circuit works in a linear state. There is a certain voltage drop on the regulating tube, and a large operating current is output. At this time, the power consumption of the adjustment tube is too large, the conversion efficiency is low, and a large heat sink is also installed.

Second, the principle of switching power supply:
The switching power supply mainly includes an input power grid filter, an input rectification filter, an inverter, an output rectification filter, a control circuit, and a protection circuit. Their function is:
1. 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 power grid.
2. Input rectifier filter: rectify and filter the input voltage of the grid to provide DC voltage to the converter.
3. Inverter: It is a key part of the switching power supply. It converts the DC voltage into a high frequency AC voltage and acts to isolate the output from the input grid.
4. Output rectification filter: Rectify and filter the high-frequency AC voltage outputted by the converter to obtain the required DC voltage, and also prevent the interference of high-frequency noise on the load.
5. Control circuit: Detect the output DC voltage and compare it with the reference voltage for amplification. The pulse width of the oscillator is modulated to control the converter to maintain the output voltage stable.
6. Protection circuit: When the switching power supply has an overvoltage or overcurrent short circuit, the protection circuit stops the switching power supply to protect the load and the power supply itself.

The switching power supply rectifies the alternating current into direct current, converts the direct current into alternating current, and rectifies the output into the required direct current voltage. This switching power supply eliminates the transformer in the linear power supply and the voltage feedback circuit. The inverter circuit in the switching power supply is completely digitally adjusted, and can also achieve very high adjustment accuracy.

News Group
Related Resources
Is There A Problem?
LYD Will provide you with more intimate service in OEM support
Request customization
Please send your enquiries to us
Contact LYD
Please send your message to us

Agree to use terms of service