Distinguish between power adapter and charger

Many people are confused about what is a charger and what is a power adapter, especially after the power adapters are made smaller and smaller, they not only look alike, but also have similar parameters, which makes us foolishly divided. Not sure.

Many people know that the power adapter starts with a laptop, and that big and bulky thing is undoubtedly the power adapter. If we think about it, we will find that what we think of as power adapters only stays on laptops. In addition, it is difficult for us to distinguish what is a power adapter and what is a charger. For example, the one below is a power adapter, but we always think it is a charger.

In fact, routers, printers, telephones, game consoles, massagers, repeaters, LCD screens, money detectors and other equipment are all power adapters. With the power adapter, small portable electronic devices and electrical appliances become external power supplies, and only one cable is needed to connect the main device, so that the size and weight of the device can be reduced. Of course, there are also very few devices that have the power supply built into the host.

Power Adapter

Taking apart an AC/DC conversion adapter, we can see that there are transformers, four diodes for bridge rectification, and electrolytic capacitors for filtering. The power adapter is actually an interface transfer device, which acts as a voltage regulator and stably introduces AC/DC power into the electrical equipment. Once there is no AC/DC power supply during this process, the power adapter will not work properly.

The power adapter is mainly divided into two types: switching power supply and linear power supply. The switching power supply maintains a stable output voltage through the ratio of the on and off time of the switch tube. The switching power supply is generally composed of a pulse width modulation (PWM) control IC and a MOSFET. The switching power supply can work in a wide voltage range, with high efficiency and small size.

The linear power supply first transforms the AC power through a transformer, and then rectifies and filters it to an unstabilized DC voltage through a rectifier circuit. In order to achieve high-precision DC voltage, the linear power supply must adjust the output voltage through a voltage feedback circuit. The linear power supply circuit is simple and mature in technology, but the equipment is heavy, so it gradually fades out of people's field of vision.

charger

When it comes to chargers, we immediately think of mobile phone chargers. Looking for the pattern, we will find that the other end of the charger usually has a power storage device that stores electrical energy, such as a lithium battery in a mobile phone. Therefore, according to the division of batteries, chargers are correspondingly divided into lead-acid battery chargers, nickel-cadmium/nickel-metal hydride chargers, and lithium battery chargers.

When we disassemble the charger, we will find that the charger contains the function of the power adapter. The charger has more control circuits than the power adapter, and it has a control chip in it. This design is for battery considerations. For example, the lithium battery in the figure below needs to go through four stages to be fully charged. Usually constant current charging is performed at the set current. When the voltage of the battery rises to 4.2V, it needs to be changed to constant voltage charging. At this time, the charging voltage needs to be maintained at 4.2V, and the charging current will gradually decrease as time goes on. Charging ends when it reaches 1/10 of the preset charging current. Obviously, the power adapter cannot do this, so a charger with a control chip is needed to charge, so as to ensure that the charging process will not be overcharged, damaged, or even exploded.