What is the difference between a switching power supply and a normal power supply?

With the development and innovation of power electronics technology, switching power supply technology is also constantly innovating. At present, switching power supply is widely used in almost all electronic equipments because of its small size, light weight and high efficiency, and is an indispensable power supply for the rapid development of electronic information industry. Switching power supply is a kind of power supply that uses modern power electronic technology to control the time ratio of switching tube conduction and shutdown to maintain a stable output voltage. Switching power supply is generally composed of pulse width modulation (PWM) control IC and MOSFET. A switching power supply is relative to a linear power supply. It directly rectifies AC power into DC power at its input, and then controls the on-off of the current with a switch under the action of a high-frequency oscillation circuit to form a high-frequency pulse current. With the help of an inductor, a stable low-voltage DC can be output. Because the core size of the transformer is inversely proportional to the square of the operating frequency of the switching power supply, the higher the frequency, the smaller the core. This greatly reduces the transformer, reducing the weight and size of the power supply. Because it controls the DC directly, this power supply is much more efficient than a linear power supply. This saves energy, so it is favored by people. However, it also has disadvantages, that is, the circuit is complex, difficult to maintain, and serious pollution of the circuit. The power supply is noisy and not suitable for some low noise circuits. Classification of switching power supply According to the way the switching devices are connected in the circuit, it can be divided into three categories: series, parallel and transformer type. Among them, transformer-type switching power supply can be further divided into push-pull, half-bridge, full-bridge and so on. According to the phase of transformer excitation and output voltage, it can be divided into forward excitation, flyback, single excitation and double excitation. Difference between switching power supply and ordinary power supply Ordinary power supply is generally a linear power supply, which is a power supply in which the regulation tubes work in a linear state. This is not the case in a switching power supply, where the switching tube operates in two states: on - with a small resistance, and off - with a large resistance. The switching power supply is a relatively new type of power supply. It has the advantages of high efficiency, light weight, can be boosted, buck, high output power and so on. However, because it is in the switching state, it is relatively noisy. The power regulator of a linear power supply always works in the amplification region and the current flowing through it is continuous. Because of the large power loss on the regulator tube, a larger power regulator tube with a larger heat sink is required. Heating is severe and efficiency is very low, typically 40% to 60%. The mode of operation of a linear power supply makes it necessary to have a voltage regulator for the change from high to low voltage. Usually a transformer, there are other power supplies like KX that rectify and output DC voltage. This is large, bulky, inefficient, and generates a lot of heat; however, it also has the advantages of low ripple, good regulation, low external interference, and is suitable for analog circuits/various amplifiers.