Switched Mode Power Supply (SMPS) is an indispensable core component in modern electronic devices. It is widely used in various fields from household appliances to industrial equipment with its efficient power conversion and compact size. With the development of technology, the types and application scenarios of SMPS are constantly expanding. This article will discuss the two most common types of switched mode power supplies in detail, and deeply analyze their characteristics and applications in the form of practical problems.

What is a buck switching power supply? How does it work?

Buck Converter is one of the most common types of switched mode power supplies. Its main function is to convert a higher input voltage into a lower output voltage while maintaining a high energy conversion efficiency. Simply put, its working principle is to adjust the output voltage through high-frequency switching and energy storage elements (such as inductors and capacitors) to achieve the purpose of voltage reduction.

Core components of step-down switching power supplies

Step-down switching power supplies are mainly composed of several key parts, including power switches (usually MOSFETs), diodes, energy storage inductors, capacitors, and control circuits. During operation, the power switch switches rapidly at a certain frequency to form an alternating on-off state. The inductor stores energy when the switch is on and releases the energy to the load when the switch is off. In this way, the input voltage is gradually converted to a lower output voltage, and the capacitor plays a role in smoothing the output voltage.

Application areas of step-down switching power supplies

Step-down switching power supplies are widely used in scenarios where higher voltages need to be converted to lower voltages. For example, in portable electronic devices such as computers and mobile phones, step-down circuits can convert battery voltages to lower voltages to supply various internal components. Step-down switching power supplies are also widely used in electric vehicles, industrial automation equipment, LED lighting, and other fields.

For example, laptops usually use a 19V power input, but internal components (such as CPUs, hard disks, etc.) only require a 3.3V, 5V, or 12V voltage supply. With a step-down switching power supply, the input voltage can be effectively reduced to these required low voltage levels and the system can be kept running efficiently.

Advantages of step-down switching power supplies

Compared with traditional linear regulators, step-down switching power supplies have higher energy conversion efficiency. During the step-down process, it reduces energy loss through high-frequency switching instead of wasting excess electrical energy as heat. Therefore, the efficiency of step-down switching power supplies can usually reach more than 90%, which makes it very popular in applications with high power requirements. In addition, due to the small size and light weight of the switching power supply, it is suitable for applications with strict space and weight requirements, such as mobile devices and embedded systems.

Working limitations of step-down switching power supplies

Although the step-down switching power supply has many advantages, it also has some limitations. First, its output voltage is always lower than the input voltage, so it is not suitable for application scenarios that require boosting. In addition, at high switching frequencies, large electromagnetic interference (EMI) may be generated, which may be a problem in some applications with high electromagnetic compatibility requirements.

How does the boost switching power supply work? In what fields is it used?

Boost Converter is another common switch mode power supply. Its function is opposite to that of buck converter, which mainly converts lower input voltage to higher output voltage. It is widely used in some scenarios where low voltage power supply (such as battery or solar cell) needs to be boosted to higher voltage to supply equipment.

Working principle of boost converter

The working principle of boost converter is similar to that of buck converter, which converts voltage by switching on and off. Its key components include power switch, diode, energy storage inductor and capacitor. When the switch is turned on, the inductor absorbs energy from the input power supply and stores it; when the switch is turned off, the inductor releases the stored energy to the load and guides the energy to the output through the diode. This process of storing and releasing energy makes the input voltage "boosted" to a higher output voltage.

Application scenarios of boost converter

Boost converter is widely used in many applications where low voltage power supply needs to be converted to high voltage power supply. For example, in a solar power generation system, the output voltage of the solar cell is relatively low, but in order to make the electric energy better used in the home grid or industrial equipment, the output voltage of the solar cell needs to be increased to a higher voltage level. In this case, the boost switching power supply can effectively increase the voltage to ensure the efficiency of power transmission and use.

In electric bicycles and electric scooters, the voltage of the battery pack is usually low, but in order to drive the motor, a higher voltage output is required. Through the boost switching power supply, the battery of the electric bicycle can increase the voltage to a suitable level to provide sufficient power for the motor. In addition, boost circuits in small devices such as flashlights are also very common. They use boost circuits to convert the low voltage of the battery to the required high voltage to light up high-brightness LED lights.

Advantages and limitations of boost switching power supplies

The main advantage of the boost switching power supply is that it can effectively convert low voltage to high voltage, especially when the input voltage is limited. Compared with traditional linear regulators, the boost switching power supply can not only increase the voltage, but also has less energy loss and high efficiency during the conversion process. Therefore, it is very popular in some scenarios that rely on low-voltage power supplies, especially in the field of portable devices and renewable energy.

However, the limitation of boost switching power supplies is that they are relatively complex to design, especially in high-power applications. If the inductor or other energy storage components are not properly selected, the system efficiency may be reduced or even the power supply may be unstable. In addition, boost power supplies also have the problem of electromagnetic interference (EMI), which needs to be taken into consideration during design to avoid interference with other sensitive devices.

How to choose the right buck and boost switching power supplies?

Faced with many different application scenarios, choosing the right type of switching power supply is the key to ensuring efficient operation of the system. Buck and boost switching power supplies each have their own advantages and scope of application, and users need to weigh them according to specific application requirements when choosing.

Selection based on input and output voltage

The first step in choosing a buck or boost switching mode power supply is to clarify the input and output voltage requirements. If the input voltage is higher than the output voltage, then the buck switching power supply is obviously the right choice; conversely, if low voltage needs to be converted to high voltage, then the boost switching power supply is the best choice. For example, if your device requires a 5V power supply and the input voltage is 12V, then a buck power supply is necessary; if you need to boost the 3.7V battery voltage to 12V to drive a device, then a boost power supply is essential.

Choose based on energy efficiency

Whether it is a buck or boost switching power supply, energy efficiency is an important criterion for selection. An efficient power supply can reduce energy loss, reduce heat generation, and extend the service life of the device. Generally, the efficiency of a switching power supply changes with the load, so when choosing, it is necessary to consider the energy efficiency performance of the device under different working conditions. Generally speaking, the efficiency of a buck switching power supply is higher than that of a boost type, but the boost type has unique advantages in low-voltage environments.

Choose based on application scenarios

Buck and boost switching power supplies have their own strengths in different application scenarios. Buck switching power supplies are suitable for scenarios that require stable, low-voltage output, such as portable devices, computer systems, etc.; while boost switching power supplies are suitable for scenarios that need to convert low voltage to high voltage, such as solar systems, LED drivers, portable charging devices, etc. Therefore, when choosing a switching power supply, it is necessary to consider the specific application scenarios and requirements to ensure that the power supply can work stably and efficiently.

Pay attention to safety and stability

Safety and stability are important factors that cannot be ignored when choosing a switched mode power supply. Whether it is a buck or boost power supply, it should have good overvoltage, overcurrent, overheating and other protection functions to prevent the equipment from being damaged by power failure. In high-power application scenarios, it is particularly important to choose a power supply with good heat dissipation and protection functions, which can not only ensure the normal operation of the equipment, but also extend the service life of the power supply itself.

What is the future development trend of buck and boost switching power supplies?

With the development of science and technology, switching power supply technology is also constantly improving. In the future, buck and boost switching power supplies will have more innovations and breakthroughs in efficiency, volume, intelligence and other aspects. Let's look forward to their future development trends.

Higher energy conversion efficiency

With the continuous emergence of new semiconductor materials, the energy conversion efficiency of switching power supplies will be further improved. For example, the application of new materials such as gallium nitride (GaN) and silicon carbide (SiC) has significantly improved the operating frequency and efficiency of switching power supplies. In the future, buck and boost switching power supplies will become more efficient, further reducing energy loss and promoting more environmentally friendly electricity use.

Smaller size and lighter weight

As the operating frequency of switching power supplies continues to increase, the size of their internal energy storage components (such as inductors and capacitors) will be further reduced. This means that future buck and boost switching power supplies will be more compact and lighter, suitable for more portable and space-constrained application scenarios. Especially in the fields of embedded devices, drones and wearable devices, the miniaturization of switching power supplies will be an important development direction.

Intelligent control and management

In the future, switching power supplies will not only be simple voltage conversion devices, but they will have more intelligent management functions. For example, by integrating microcontrollers and sensors, switching power supplies can monitor and adjust parameters such as output voltage, current, and temperature in real time, thereby improving the stability and safety of the system. In addition, intelligent switching power supplies can also achieve more refined power management through remote monitoring and management to meet the needs of various complex applications.

Wider application scenarios

With the popularization of renewable energy and Internet of Things technology, the application scenarios of buck and boost switching power supplies will be more extensive in the future. For example, with the development of photovoltaic power generation and energy storage technology, boost switching power supplies will play a more important role in solar and wind energy systems; while in IoT devices, buck switching power supplies can provide efficient power support for various low-power sensors and communication devices.

Conclusion

Buck and boost switching power supplies are the two most common power conversion technologies in modern electronic devices. By deeply understanding their working principles, application areas, advantages and limitations, we can better choose power supply equipment that suits our needs. In the future, with the continuous advancement of technology, these two switching power supplies will become more efficient and intelligent, and play an important role in more emerging fields. Whether it is industrial automation, renewable energy or IoT devices, buck and boost switching power supplies will provide more stable and efficient power support for modern life.