Introduction to the type and function of the power adapter

In some small portable electronic devices such as telephone handsets, game consoles, language repeaters, walkmans, laptops, cellular phones, etc., we often have power adapters. So what is the power adapter? What is the role? 

What is the power adapter? The power adapter is also called an external Power Supply. It is a power supply voltage conversion device for small portable electronic devices and electronic appliances. Its function is to convert the 220 volt high voltage in the home into a stable low voltage of 5 volts to 36 volts. The voltage makes them work properly.

1, the type of power adapter

The power adapter is mainly divided into two types, a switching power supply and a linear power supply.

1) Switching power supply is a kind of power supply that uses modern electronic technology to control the ratio of time when the switch is turned on and off, and maintains a stable output voltage. The switching power supply of the power adapter is generally composed of a pulse width modulation (PWM) control IC and a MOSFET.

Advantages: high work efficiency, small size, can work in a wide voltage range.

Disadvantages: The interference to the power supply circuit is large, and it is difficult to repair when the fault occurs.

2) The linear power supply converts the alternating current through the Transformer, and the rectifier circuit rectifies and filters to obtain the unsteady DC voltage. To achieve the high-precision DC voltage, the power adapter must adjust the output voltage through the voltage feedback circuit.

Advantages: This power supply technology is mature, the circuit is simple, and there is no interference and noise from the switching power supply.

Disadvantages: The voltage feedback circuit works in a linear state. The power consumption of the adjustment tube is large, and the conversion efficiency is low. Because of the use of an inductive transformer, the weight of the device is large.

2, the nameplate of the power adapter

There is a nameplate on the power adapter that indicates the power, input and output voltage and current amount. There are generally several items that need to be noted on the label of the power adapter (hereafter referred to as the adapter). The first is the model of the adapter. For example, the model of this adapter is ZF120A-1202000. It tells us a few information, that is, its manufacturer, main parameters, etc. The beginning of ZF120A is generally ##公司码号, 1202000 is to explain this Adapter is 24W, 1203000 is 36W; the second is the INPUT (input) of the adapter, which is generally 100-240V~50-60Hz in China, which means that the adapter can work under the voltage of 100V-240V. The third is the OUTPUT (output) of the adapter. The two numbers can quickly calculate the wattage of the adapter. For example, the adapter, voltage 12V* current 2A24W (power), indicates that the power supply is a 24W adapter.

3, the role of the power adapter

The power adapter acts as a transformer and rectifier. The household AC is 220v, and our computer land is DC 12v (as if it is), so we can be sure that the power adapter is a transformer and rectifier. Then the adapter is a transformer, we should all know that the AC 220V is transformed by the transformer, and the DC is changed by the rectifier. Here, there is consumption, and these consumptions are converted into heat, so it is normal for the power adapter to heat up. The transformer is made of silicon steel sheet. When the transformer is energized, magnetic flux is generated. The magnetic flux will cause a force between the silicon steel sheets to generate a click sound, which is normal. However, the sound of the earth is not normal, and there are many reasons: 1. The AC voltage is unstable. 2, the chip is damaged. 3. Short circuit between turns. 4. Component damage.

4, the application of the power adapter

It is widely used in consumer electronics, and the output power is mostly within 100 watts, and the market demand is growing rapidly. Applications such as electric bicycle battery chargers, small size LCD TVs, laptops, printers, DVD players and set-top boxes are available. Most of the early power adapters used linear transformers. As consumer electronics products have high efficiency, wide input voltage range, and increased copper, iron, and labor costs, the original linear transformers in these power adapters are gradually increasing. Replaced by switching power supply.