The power adapter we see now uses power electronics technology, uses power semiconductor devices as switches, and adjusts the output voltage by controlling the time ratio of switching transistors on and off.
Before the 1980s, the external power supply was mainly linear power supply. Its disadvantages are that it is larger in size and weight than the power adapter, and its efficiency is low. However, its advantages are stable operation and simple circuit, but it is not convenient to carry. Therefore, in the mid-1980s, Japan’s Toshiba took the lead in applying switching power supply technology to the external power supply of notebooks. Its pioneering work created a new page in the history of power adapter development and became the world’s first independent notebook power adapter, because The power supply using the switching power supply technology is external, so the notebook does not need to consider that the heat generated by the power conversion is gathered in the notebook itself, and the power adapter is easy to carry, which effectively improves the commercialization and popularization of the notebook computer.
Since Toshiba launched the notebook power supply and realized the switching power supply in an all-round way, and took the lead in completing the computer power supply replacement, notebook manufacturers followed suit, thus becoming a pioneer and example for power adapter applications and other industries. In the 1990s, power adapters have been widely used in various electronic products. , Electrical equipment, program-controlled switches, communications, power testing equipment power supply and control equipment power supply. A power adapter is generally composed of a pulse width modulation (PWM) control IC and a MOSFET.
Compared with the linear power supply, the cost of the power adapter and the linear power supply both increase with the increase of the output power, but the growth rates of the two are different. At a certain output power point, the cost of linear power supply is higher than that of switching power supply, which is called the cost reversal point. With the development and innovation of power electronics technology, the power adapter technology is also constantly innovating. This cost reversal point is increasingly moving to the low output power end, thus providing a broad development space for power adapters.
At the end of the 1990s, Europe proposed a series of standards on power conversion efficiency and standby power consumption, which pushed the power adapter to an unsurmountable height. The high frequency of the power adapter makes it the direction of development, and the high frequency makes the switching power supply miniaturized, and makes the power adapter more widely used, especially in the application of high-tech fields, which promotes the miniaturization of high-tech products, portability. In addition, the development and application of power adapters are of great significance in saving energy, saving resources and protecting the environment.
In 2001, Apple developed a stylish and lightweight power adapter, which pushed the power adapter to another new peak. The previous appearance was monotonous and unattractive. And just in 2001, a group of power adapter manufacturers developed and mass-produced the world’s first universal notebook chargers that are fully compatible with notebook computers of all major brands in the world. Bring the notebook power adapter into the era of real universal.
It can be said that there is a close relationship between the development of power adapters and notebooks. Several times, the development of the entire power adapter has been driven by the power adapter for notebooks. The development direction of the power adapter is high frequency, high reliability, low consumption, low noise, anti-interference and modularization. Because the key technology of light, small and thin power adapter is high frequency, power adapter manufacturers are committed to synchronously developing new high-intelligence components, especially improving the loss of the secondary rectification device, and the power ferrite (Mn -Zn) material to increase technological innovation to improve the high magnetic performance at high frequency and large magnetic flux density (Bs), and the miniaturization of capacitors is also a key technology.
The application of SMT technology has enabled power adapter manufacturers to make great progress, arranging components on both sides of the circuit board to ensure that the switching power supply is light, small and thin. The high frequency of the power adapter will inevitably innovate the traditional PWM switching technology, and the soft switching technology of ZVS and ZCS has become the mainstream technology of the power adapter, and the working efficiency of the power adapter has been greatly improved. To improve the reliability index, power supply manufacturers reduce the stress on the device by reducing the operating current and junction temperature, which greatly improves the reliability of the product.