The switching power adapter is composed of full-wave rectifiers, switch tubes, excitation signals, freewheeling diodes, energy storage inductors, and filter capacitors. In fact, the core part of the switching power adapter is a DC-DC converter. Here we explain the DC converter and inverter as follows. Inverter, which is a device that converts DC into AC. Inverters are often widely used in standby power supplies that use a level or battery. A DC-DC converter, which converts DC to AC first and then converts AC to DC. This device is widely used in switching power supplies. Using a DC-DC converter can convert a DC supply voltage into a variety of DC supply voltages with different polarity and values.
The switching power adapter is a power supply conversion device for small portable electronic devices and electronic appliances.
Switching power adapters typically consist of a housing, a switch, a power transformer, and a rectifier circuit.
Switching power adapter can be divided into AC output type and DC output type according to its output type; according to the connection mode can be divided into wall type and desktop type.
Switching power adapters are widely used in telephone handsets, game consoles, speech repeaters, portable music players, notebook computers, and cellular phones.
Switching power adapter has a compact appearance, easy to carry, versatile and versatile, suitable for a variety of environments, quality and other advantages.
1. Small size and light weight. Switching power adapters do not use cumbersome power frequency transformers. Since the dissipated power on the switch MOS tube is greatly reduced, a large heat sink is eliminated. Because of these two reasons, the switching power adapter is small and lightweight.
2. Low power consumption and high efficiency. Switching power adapter circuit, the switch MOS tube under the excitation of the excitation signal, it alternately operates in the on-off and cut-off switch state, switching speed is fast, the frequency is generally above 50kHz, in some advanced switches In power lines, hundreds or nearly megahertz can be achieved. This makes the power consumption of the switching MOS transistor very small, the efficiency of the power supply can be greatly improved, and its efficiency can reach 90%.
3. The efficiency of filtering is greatly improved, so that the capacity and volume of the filter capacitor are greatly reduced. The operating frequency of the switching power adapter is basically above 50 kHz, which is more than 1000 times that of the linear regulated power adapter. This makes the rectified filtering efficiency almost 1000 times faster; even after half-wave rectification plus capacitor filtering, The efficiency has also been increased by 500 times. With the same ripple output voltage, when the switching power supply is used, the capacity of the filter capacitor is only 1/500 to 1/1000 of the filter capacitance in the linear regulated power supply.
4. Wide voltage range. The output voltage of the switching power adapter is adjusted by the duty cycle of the excitation signal, and the variation of the input signal voltage can be compensated by frequency modulation or widening. In this way, it can still guarantee a more stable output voltage when the power frequency grid voltage changes greatly. Therefore, the switching power adapter has a wide range of voltage regulation, and the voltage regulation effect is very good. In addition, pulse width modulation type and frequency modulation type are two methods to change the duty ratio. The switching regulated power supply not only has the advantages of wide voltage regulation range, but also has many methods for achieving the voltage regulation. The designer can flexibly select various types of switching power supply integrated circuit chip solutions according to the requirements of practical applications.