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What is the difference between linear power supply and switching power supply?
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What is the difference between linear power supply and switching power supply?

Time:2021-04-13  /  Read:55

Power supply are generally divided into three types: LPS linear power supply, UPS uninterruptible power supply, SMPS switching power supply.

What is a linear power supply:

Linear power supply (LPS) is to reduce the voltage amplitude of AC power through a transformer, then rectify it through a rectifier circuit, and then filter to obtain a DC voltage with a smile ripple voltage. To achieve high-precision DC voltage, it must be stabilized by a voltage regulator circuit.

 

What is a switching power supply:

Switching power supply (SPS), also known as switching power supply, switching converter, is a high-frequency electric energy conversion device and a kind of power supply. Its function is to convert a level of voltage into the voltage or current required by the user through different forms of architecture. The input of the switching power supply is mostly AC power or DC power, and the output is mostly equipment that requires DC power.

The following lists the working principles and advantages and disadvantages of linear power supply and switching power supply, such as:

 

The working principle of linear power supply and switching power supply:

The linear power supply is after the input power has undergone preliminary AC voltage stabilization through the pre-regulated circuit, it is converted into a DC power supply through the isolation and rectification of the main working transformer. The linear adjustment element performs fine adjustment to make it output a high-precision DC voltage source.

Switching power supply uses electronic switching devices (such as transistors, field effect transistors, thyristors, etc.) to make the electronic switching devices "on" and "off" continuously through the control circuit, allowing the electronic switching devices to The input voltage is pulse-modulated to achieve DC/AC, DC/DC voltage conversion, as well as adjustable output voltage and automatic voltage stabilization.

 

advantage:

The linear power supply technology is very mature, the production cost is low, it can reach a high degree of stability, the ripple is also very small, and there is no interference and noise.

The switching power supply has high efficiency because there is no power loss in the whole circuit, and the switching frequency becomes higher after the module.The switching power supply does not have a bulky line frequency transformer, and the volume becomes smaller, the noise is lower, and the weight is lighter; the transformer in the switching power supply is smaller than the traditional line frequency transformer (expensive), so the cost is greatly reduced.

 

Disadvantages:

The linear power supply has low efficiency and narrow input range; the transistor loss in the linear state is very large, and the input voltage range requires a high input voltage range. The transformer is bulky and bulky and is not suitable for most industrial applications.

Switching power supply has large electromagnetic interference and large ripple coefficient, especially in the range of audio and video, it is very sensitive to electromagnetic interference.

 

Scope of application:

Linear power supplies are used in studio mixers/audio amplifiers, low-noise amplifiers, signal processing, data acquisition, including sensors, multiplexers, automatic test equipment, laboratory test equipment, etc.

Switching power supplies are used in military equipment, scientific research equipment, LED lighting, industrial control equipment, communication equipment, power equipment, medical equipment, liquid crystal displays, LED lamps, LED strips, etc.