Switched mode power supply (SMPS), also known as "switching power supply", is an efficient electronic device that converts electrical energy into voltage and current that meet specific requirements. SMPS can convert the form of current in different application scenarios: such as converting direct current (DC) to alternating current (AC) in AC adapters, or converting alternating current (AC) to direct current (DC) in computers and laptops. SMPS uses a switching regulator to operate transistors in low-power modes of full on and full off, effectively reducing energy waste. Ideally, SMPS consumes almost no energy. Its operating frequency is usually between a few thousand hertz and a few megahertz, while the typical AC main frequency is 50 to 60 hertz. This efficient power supply device is widely used in scenarios that require high efficiency, lightness or small size to replace traditional linear power regulators. However, due to the complexity of the design, SMPS may generate electrical noise if proper noise suppression is not performed.

The concept of switching mode power supply was first proposed by Hewlett-Packard in 1972 and was originally designed for portable calculators. Later, due to the potential of SMPS in power supply, Hewlett-Packard improved the design and finally obtained a patent in 1976.

Importance of SMPS in daily life

In today's rapidly developing modern technology and computer technology, stable power supply is the core guarantee for the normal operation of electrical equipment. Especially in scenarios where electronic equipment needs to be used frequently, traditional power regulators are inefficient and generate a lot of heat and energy waste. The emergence of SMPS is just right. It can accurately adjust the voltage and current according to the needs of the equipment and provide power in an efficient and reliable way. In addition, the lightweight and compact design of SMPS is also very suitable for environments that require compact layout (such as computers, mobile devices, electric vehicles, etc.).

Advantages of SMPS

High efficiency and energy saving: The efficiency of SMPS is usually between 80% and 90%, while the efficiency of traditional power supply equipment is about 60% to 70%. Higher conversion efficiency means lower energy waste, which helps save electricity bills.

Lightweight and compact: SMPS is compact in design, small in size and light in weight. Compared with other larger and heavier regulators, this design makes the equipment easier to arrange and can significantly save space, especially suitable for the miniaturization design requirements of electronic products.

Low heat generation: Because SMPS can quickly and efficiently complete high-power conversion, the heat generated is low, avoiding equipment failures caused by poor heat dissipation. In addition, low temperature operation helps to extend the service life of the equipment.

Reduced harmonic feedback: SMPS can rectify and filter low-frequency input current, then adjust the voltage through a high-frequency converter, and finally rectify and filter the output. This process greatly reduces the harmonic feedback of the power grid, which is beneficial to the stability of the power system.

Diverse voltage output: The significant feature of SMPS is that it can flexibly provide different voltage outputs according to the needs of the equipment. For equipment requiring different voltages, SMPS is much more adaptable than other traditional power supplies.

Low manufacturing cost and easy maintenance: SMPS has a relatively low production cost and a modular design that makes it easy to maintain. In the event of a failure, the maintenance cost is also lower than that of traditional regulators.

Disadvantages of SMPS

Despite the many advantages of SMPS, there are also some disadvantages that need to be noted:

Complex circuit: The circuit design of SMPS is relatively complex, and its production requires a high level of professional design and technical support. Although there are some SMPS with simplified designs on the market, this design usually sacrifices efficiency and power factor.

Single output: SMPS can usually only provide a single voltage output, which means that it cannot provide power to multiple devices at different voltages at the same time.

High-frequency noise: SMPS generates high-frequency noise when working at high-frequency switching. Although the noise can be reduced by adding additional rectifiers, it will affect the compactness of the device.

Harmonic distortion: Under high load, SMPS may cause harmonic distortion, causing the power supply equipment to heat up. Harmonic distortion will affect the performance of equipment such as computers and monitors, and may even affect the service life of the equipment.

Electromagnetic interference: SMPS may generate electromagnetic interference (EMI), which in some applications will cause the equipment to emit a "buzzing" sound, which may be uncomfortable in a quiet environment.

Comparison between SMPS and Linear Power Supplies

The following aspects can better understand the difference between SMPS and traditional linear power supplies:

Energy loss: SMPS has lower energy loss and its power conversion efficiency is significantly better than that of linear power supplies, which makes it outstanding in scenarios where efficient power supply is required.

Circuit complexity: The circuit structure of SMPS is more complex, but the higher design difficulty brings better performance. In contrast, the design of linear power supplies is simpler, but the efficiency is low and the volume is large.

Electrical noise: The electrical noise at the output of SMPS is large, which may cause unstable operation of electronic equipment if not properly filtered. The output of linear power supplies is relatively stable and has lower harmonic distortion.

Application of SMPS

Switching mode power supply is widely used in various scenarios that require low voltage or stable power supply. Its common applications include:

Lighting: SMPS is widely used in low-voltage lighting power supply. Because of its energy-saving and compact size, it is often called "electronic transformer".

Automobile: In automotive electrical systems, SMPS is used to provide stable power supply for various electronic devices.

Computers and industrial equipment: Under the requirements of efficient operation and low energy consumption, SMPS is widely used in electronic devices such as computers and monitors.

Some common SMPS brands on the market include:

NVVV Intelligent Switching Power Supply
NVVV Power Module Series
NVVV DC-DC and AC-DC Converter Series

Precautions for Using SMPS

Since the CR filter capacitor of SMPS sometimes stores voltages up to 325 volts, improper operation may cause serious electric shock injuries. Therefore, when repairing or touching the equipment, direct contact with the capacitor part should be avoided to ensure safety. In addition, appropriate protection measures such as electromagnetic shielding should be installed in SMPS equipment to reduce possible electromagnetic interference.

Conclusion

SMPS, as an efficient and compact power supply device, has both significant advantages and some problems that need to be overcome. When deciding whether to use SMPS, specific application requirements should be considered. For example, if your main needs are high efficiency, energy saving and small size, then NVVV's SMPS series is an ideal choice. Although SMPS may bring some electrical noise and electromagnetic interference problems, these problems can basically be solved through proper design and adjustment. However, while improving noise suppression and electromagnetic interference, some compactness and cost advantages may be sacrificed.

In general, switch mode power supply is a very practical power supply device, especially suitable for use in devices that require efficient power management, such as computers, desktops or laptops.