SMPS can achieve higher efficiency

Due to the continuous advancement of technology and the introduction of recommended and mandatory standards, the energy efficiency of Power Supplies is constantly improving. It is estimated that the number of electronic products in use in the United States alone amounts to 2.5 billion pieces, and 400-500 million new power supplies are sold each year. Therefore, improving Power Supply efficiency is critical for energy efficiency, reducing pressure on global energy sources, and Mitigating the adverse impact of technology applications on the environment is crucial. However, since the installation and selection of the power supply is usually in the late stage of the entire product development process, the time to optimize the target application design is very short, and there is not much choice in terms of procurement cost.

Under the combined effect of economic growth, rapid technological development, and continuous population expansion, the growth of world energy consumption is expected to be as high as 50% between 2005 and 2030, which is equivalent to a sharp increase from 462 × 1015 BTU in 2005 to 695 × 1015BTU in 2030 (Source: US Energy Information Administration).

Such a huge amount of energy consumption is beyond the tolerance of nature, and it will have an increasing impact on the environment and the lives of global residents, because the traditional solution to the increase in energy demand is to build more coal, natural gas, and nuclear energy. And oil-fired power plants to increase power supply. Although research and development and application of renewable energy in the form of hydropower, biofuels, wind energy and solar energy have made great progress, our dependence on fossil fuels means that we must significantly improve energy efficiency; this is reflected in two aspects : The way we use electrical products and their inherent energy efficiency.

Initiatives According to the analysis of the American Energy Conservation and Economic Commission (ACEEE), in the United States, energy conservation initiatives are expected to reduce energy consumption by 10.6 × 1015 BTU, which is roughly equivalent to 10% of the US ’s estimated energy use in 2020.

Initiatives such as "Energy Star" have been very successful and are currently used to identify approximately 60 different categories of products that meet the standard. Many countries around the world are coordinating energy efficiency guidelines by obtaining "Energy Star" certification. So far, Europe, China and Australia have all signed agreements to recognize this initiative.

Some governments have adopted mandatory standards and adopted a tougher stance. Considering the future environmental challenges, this approach is expected to become the general trend.
Some countries have gradually implemented stricter standards to promote continuous improvement. For example, Japan ’s “leader” plan first identified the most energy-efficient products among various products on the market, and then required all competing brands to improve product energy efficiency within 4 to 6 years. Companies that do not meet energy efficiency standards will face financial penalties. All relevant regulations formulated by countries around the world, whether mandatory or recommended, take the energy waste caused by the power supply in standby mode and use mode as the key improvement target.

Types of power supply and selection of power supply for electronic equipment can be roughly divided into linear power supply and switching power supply (SMPS): the design of linear power supply is very simple, while SMPS is more complicated. The typical efficiency value of a linear power supply is between 40% and 55%, while SMPS can achieve a much higher nominal value of efficiency, between 60% and 95%.

If only the comparison of energy efficiency is considered, and designers want to make their new products meet recommended or mandatory standards, obviously SMPS is the best choice. However, two other factors may affect the choice of power supply.

Compared to linear power supplies, SMPS is more complex, which usually means higher material costs. At the same time, the more advanced, more efficient and smaller tolerance components used in some layouts are often more expensive than ordinary performance components. The design of a linear power supply is simpler, but it requires the use of components such as iron core transformers and requires a large number of copper coils-which may affect the cost. In general, the increased cost of SMPS is limited, sometimes lower than the incremental cost of inefficient linear power supplies.

In order to promote the wider application of the more energy-efficient SMPS method, it is important to make its cost close to or lower than that of linear power supplies. This is because when users end up facing two products with the same performance, they tend to choose the one with lower cost. At the same time, consumers' environmental awareness continues to increase, and they begin to consider the overall purchase cost-that is, the initial purchase cost and the energy cost of the product throughout the life cycle-this concept has been slowly gaining popularity.

Linear power supplies are usually larger and heavier than SMPS. Compared with the design of integrating the power supply function into the product casing, the design method of the external power supply is less affected by this problem. In the integrated design method of the power supply function, the linear power supply not only occupies precious space, but because of its low efficiency, the large amount of waste heat generated by it must be managed by heat dissipation in order to ensure a long service life and reliability of the device. If the target device wants to be designed to be portable, then the heavier power supply will also cause problems.

SMPS advanced layout is more efficient, smaller and lighter. SMPS represents the trend of technological development. With the support of advanced integrated AC / DC controller and rectifier equipment (such as products provided by ON Semiconductor and other companies), a new layout that supports low-cost and high-efficiency SMPS design can be realized.

Many SMPS-related losses are related to the switching process. Soft switching techniques and layouts like half-bridge and full-bridge can overcome these losses. In addition to improving efficiency, these layouts also help increase the density of power converters (in W / in.3) —a key requirement for many new product designs. Previously only used for high-power applications (for example, 500W or 1kW) layout, because they can have an impact on efficiency and power density, is currently being gradually adopted by medium-power or low-power applications (for example, 100W).

Reference designs Reference designs such as ON Semiconductor ’s "green dot" (see Figure 1) provide manufacturers with a "turnkey" solution that can meet or exceed the minimum energy efficiency standards in many applications, such as desktop computers and set-top boxes , Notebook AC / dc adapter and LCD TV. By providing tools that simplify the design of energy-efficient products, it is possible to speed up the process of improving the efficiency of most electronic products (up to the range of 80% or 90%). It is estimated that using a reference design method like "green dot" can increase the efficiency of household products by 20%, while the efficiency of office equipment products can be increased by 15%.

Figure 1 ON Semiconductor's "green dot" reference design

High-efficiency SMPS can significantly increase the efficiency of electronic devices. Since the costs of SMPS and linear power supplies are about the same, this presents a huge opportunity to significantly improve the efficiency of many types of products. This will help equipment manufacturers meet or exceed recommended energy efficiency standards and mandatory performance efficiency standards that are gradually becoming popular. There is a contradiction between the rising use of electronic devices and energy sustainability, which means that we must seek change, and significantly improving power efficiency will play an important role in achieving this goal.