Types of power adapters

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  • Jimmy at
  • October 14, 2019

Types of power adapters


There are two main types of power adapters, linear power supply and switching power supply.

1.     Linear power supply transforms AC through transformer, rectifier circuit rectifier filter to get unstable DC voltage. To achieve high precision DC voltage, power adapter must adjust output voltage through voltage feedback circuit. Advantages: The power supply technology is mature, the circuit is simple, and there is no interference and noise of switching power supply. Disadvantage: Voltage feedback circuit is in an on-line state. The power consumption of the regulator is large, the conversion efficiency is low, and the weight of the equipment is large because of the use of inductance transformer.

2. Switching power supply is a kind of power supply which uses modern electronic technology to control the time ratio of switching on and off, and maintain stable output voltage. The switching power supply of power adapter generally consists of pulse width modulation (PWM) to control IC and MOSFET. It has the advantages of high efficiency, small size and can work in a wide voltage range. Disadvantage: The power supply circuit is disturbed greatly, and it is difficult to repair when a fault occurs.

12W power adapter

Then the power adapter is a transformer. We should all know that 220 V AC is transformed by transformer and DC by rectifier. There is consumption here, and these consumption will turn into heat, so it is normal that the power adapter will heat up. Transformers are made of silicon steel sheets. When the transformer is electrified, it produces magnetic flux. The magnetic flux will cause a strong interaction between the silicon steel sheets, thus generating buzzing sound. This is normal. But the sound of overheated earth is abnormal for many reasons:

1. The AC voltage is not stable.

2. Chip breakage.

3. Interturn short circuit.

4. Component damage.

It is widely used in consumer electronics products. Most of the output power is within 100 watts, and the market demand is growing rapidly. For example, electric bicycle battery charger, small size LCD TV, notebook computer, printer, DVD player and set-top box have applications. Early power adapters mostly used linear transformers. With the requirement of high efficiency and wide input voltage range for power adapters in consumer electronics products, and the increase of copper, iron and human costs, most of the original linear transformers in these power adapters were gradually replaced by switching power supply.

It is not difficult to distinguish them according to their advantages and disadvantages. It mainly depends on volume, weight and output voltage range. Transformer type, through coil step-down, post-stage rectifier, voltage stabilization, large volume, stable performance, shortcomings of high cost transformer, easy to heat. The switch type is small in size and low in cost, but it is easy to be damaged if the quality of components is not good. The distinction mainly depends on volume and weight, and the difference is obvious.