MPS welcomes the new low-carbon era with new ACDC power solutions

The low-carbon era is coming, leading the trend of miniaturization and high efficiency

After the switching power supply replaced the linear power supply in the 1980s, the power supply efficiency has been greatly improved and the size has been greatly reduced. With the continuous development of switching power supplies in various applications and consumers' demand for portability, switching power supplies continue to develop in the direction of miniaturization and lightweight. In recent years, the "3060" goal of carbon peak and carbon neutrality has ushered in a new era of low carbon. As the requirements for energy conservation and emission reduction become more and more stringent, people have put forward higher requirements for environmental protection, energy conservation, low consumption and greenness, and the energy efficiency standards for switching power supplies have become more and more stringent. For example, the latest CoCV5 six-level energy efficiency standard of the European Commission, the second phase, and the six-level energy efficiency of the US Department of Energy DoE6 have higher requirements for no-load power consumption and efficiency to achieve the goal of energy conservation and emission reduction.

The challenges of switching power supplies continue to escalate

Increasing the switching frequency can greatly reduce the size of passive components, including inductors, capacitors and transformers. For AC/DC offline switching power supplies, the input is 50Hz/60Hz 230V AC input. The switching loss caused by high-frequency switching of high voltage limits its switching speed. Traditional 700V silicon power devices have developed from 30kHz at the beginning to 200kHz now, and have encountered the physical bottleneck of Si. In AC/DC power supplies, in addition to the switching frequency limit of high-voltage power devices, the high-frequency design of isolation transformers must also take into account safety and efficiency. As the frequency increases, the increase in heat dissipation per unit volume also greatly restricts the increase in frequency.

Improving efficiency is the only way forward

Improving efficiency is a necessary way to miniaturize, which can not only reduce losses, but also reduce heat dissipation, providing the necessary conditions for high-frequency miniaturization. Only when efficiency is improved, heat dissipation per unit volume is reduced, and high-frequency design is used, power density will be greatly improved.

To improve efficiency, new switch topologies can be used, such as the new flyback topology ACF (Active-Clamp Flyback), which can eliminate turn-on losses and recover the leakage inductance of the isolation transformer. With the rapid shutdown of the third-generation semiconductor power devices, the switching losses can be reduced to negligible levels. This improves efficiency and allows the design frequency of the power supply to not be limited by the power devices, greatly accelerating miniaturization.

Figure 1: GaN+ new topology improves efficiency

MPS has been deeply involved in the ACDC field for many years and has industry-leading products covering the 1~1000W product range on the market, with customers all over the world. With the introduction of new "greener/environmentally friendly" regulations and the advent of the third-generation semiconductor era, MPS's AC/DC power products continue to improve technology and performance to meet market development trends:

● Use a variety of new topologies to improve efficiency: for example, use a hybrid topology of PFC + LLC and ACF + ZVS to achieve zero turn-on loss while recycling leakage inductance to achieve a high efficiency of more than 93%.

● Adopt a fully integrated design to simplify the design and reduce costs: Traditional non-isolated AC/DC solutions usually require the use of multiple ICs, and are also equipped with primary and secondary side controllers and optical isolators, which occupy a large board area and have high BOM costs; MPS's latest generation of solutions are compact in size and highly integrated. One IC can include the primary side and synchronous controller. It has a simple design, a small board area, and is cost-effective.

● High-frequency chips to adapt to the new generation of power devices: Traditional silicon devices have low switching frequencies and it is difficult to improve their efficiency. With the emergence of new semiconductor materials such as GaN, their switching frequencies and efficiency have been greatly improved, and high-frequency design is more in line with the requirements of new power devices.

● Digital products can achieve better performance: Traditional analog controllers find it difficult to keep up with the rapid changes. The advantages of the new generation of digital power chips are becoming increasingly obvious. MPS products use digital cores and have a very rich range of configurable items, which are more flexible than traditional controllers.

MPS can provide a full range of 0-1000W AC-DC power supply solutions, from 1W output smart LDO and Buck non-isolated solutions to 10W output non-isolated buck solutions, MPS has integrated power tube solutions. For small power isolated flyback solutions, MPS also provides integrated power tube and controller solutions. Finally, for high-power LLC solutions, above 75W output, the more commonly used PFC+LLC architecture, MPS provides independent PFC controllers and LLC controllers.

Figure 2: MPSACDC power solution

Among them, the fully integrated flyback controller series MPX2002/3 innovatively combines the primary and secondary controllers into one chip, greatly simplifying the peripheral circuit design and providing a new idea for miniaturizing fast-charging power supplies.

Figure 3: MPX2002 typical application circuit (primary side + secondary side + feedback)

The MPX2002 can operate in CCM under heavy load, and then switch to quasi-resonant (QR) operation when the load decreases. If the load decreases further, the MPX2002 will operate in frequency hopping (PFM) mode. When it enters burst mode, the switching frequency is fixed at 20kHz, which reduces audio noise. With this feature, the MPX2002 can achieve high efficiency under all load conditions while having excellent electromagnetic interference (EMI) performance. The traditional solution requires four ICs: flyback controller, optocoupler, voltage reference and synchronous rectification controller, while the MPX2002 single IC solution integrates the primary controller and synchronous rectification controller. It simplifies the design, improves efficiency, reduces the board area, reduces standby power consumption, enhances reliability, does not require optocoupler feedback, and prevents optocoupler aging in a high reliability environment. Especially in CCM operation mode, more accurate synchronous rectification control can be achieved. MPX2003 further increases the frequency to more than 130kHz to meet the needs of miniaturization.

Figure 4: MPX2002 VS. Traditional Solution

Another famous product of MPS AC/DC, HR1211, also fully reflects the product advantages of MPS. It is a two-in-one controller integrating multi-mode PFC and current-type LLC. The chip integrates high-voltage current source, safety-certified X-capacitor discharge circuit, and high-voltage drive circuits for PFC and LLC, thus realizing a very simple peripheral circuit.

Figure 5: Typical application circuit of HR1211

The digital control core of HR1211 combined with the re-editable storage unit gives the whole solution great flexibility. The coordination between the PFC and LLC circuits; the switching between different control modes; the switching frequency of the key working point; the threshold, time and recovery method of the protection function; all these main functions can be freely configured through the UART communication port and can be completed on the graphical operation interface, which makes the power supply design based on HR1211 flexible to adapt to the performance requirements of different applications in different designs.

Figure 6: HR1211 application scenarios

MPS has accumulated technology in the AC/DC field for many years. Currently, it has many excellent solutions that are well received by the industry, and more new products will be launched in the future.

About MPS

Monolithic Power Systems, Inc. (MPS) is a leading global semiconductor company that focuses on the design, development, manufacturing and sales of high-performance analog integrated circuits and mixed-signal integrated circuits. Its products are widely used in automotive electronics, cloud computing, storage, communications, industry, consumer electronics and other fields. MPS was founded in 1997 and successfully listed on NASDAQ in 2004. Its current market value exceeds US$15 billion. After more than 20 years of global market expansion, MPS currently has 16 branches in Asia Pacific, North America, Europe and other regions, with business covering more than 30 countries and regions around the world, more than 10,000 global customers, and a total shipment of 100 billion chips.