The current trend of power electronics technology in power modules is low voltage and high current. This makes the use of synchronous rectification technology in the secondary rectifier circuit an efficient and low-loss method. Because the on-resistance of the power MOSFET is very low, which can improve the efficiency of the power supply, products have begun to be formed in DC / DC converters using isolated buck circuits. The schematic diagram of synchronous rectification technology is shown in Figure 1.
Synchronous rectification technology is a technology that utilizes power MOSFET to realize the rectification function by controlling the drive circuit of power MOSFET. Generally, the driving frequency is fixed and can reach more than 200kHz. The gate drive can be implemented by cross-coupled or external driving signals in conjunction with dead time control.
Application of synchronous rectification technology
Synchronous rectification technology appeared earlier, but the early technology is difficult to convert into products, which was because
1) The driving technology is immature and the reliability is not high. Now that the technology has gradually matured, a dedicated synchronous rectification driver chip has appeared, such as IR1176;
2) The special supporting low on-resistance power MOSFET has not been put on the market;
3) MOSFETs are not used in parallel Schottky diodes to reduce the conduction loss of parasitic diodes;
4) The influence of distributed inductance on the switching loss of MOSFET is not solved in the product design.
After several years of development, the synchronous rectification technology has matured. Due to development costs, it is currently only used in communication power modules with a relatively high technical content. Companies such as Synqor, Tyco, Ericsson and others have launched products that use synchronous rectification technology.
The current power module is still mainly used in communication systems. With the development of communication technology, the voltage required for communication chips has gradually decreased. 5V and 3.3V have already become the mainstream and are developing in the direction of 2.5V, 1.5V or even lower. The integration of communication equipment continues to increase, the power of the single machine in the distributed power system continues to increase, and the output current is from the early 10-20A to the current 30-60A, and there is a trend of increasing, while requiring the volume to continue to decrease. This provides a wide range of application requirements for synchronous rectification technology.
Comparison between synchronous rectification technology and traditional technology
In traditional secondary rectifier circuits, Schottky diodes are the first choice for low-voltage, high-current applications. The turn-on voltage drop is greater than 0.4V, but when the output voltage of the communication power supply module gradually decreases with the development of communication technology, the efficiency loss of the power supply module using Schottky diodes is amazing. When the output voltage is 5V, the efficiency can reach 85 When the output voltage is 3.3V, the efficiency drops to 80%, and when the output voltage is 1.5V, it is only 65%. The application is unrealistic.
In low output voltage applications, synchronous rectification technology has obvious advantages. Power MOSFET has strong on-current capability, which can reach more than 60A. After the synchronous rectification technology is adopted, the voltage drop of the secondary rectification is equal to the on-voltage drop of the MOSFET, which is determined by the on-resistance of the MOSFET, and the progress of the control technology also reduces the switching loss of the MOSFET. In the past three years, MOSFET technology for synchronous rectification has made breakthrough progress, and the on-resistance has dropped to 1/5. Now, MOSFETs processed by special processes can achieve very low on-resistance, such as IR's product IRHSNA57064. When the on-current is 45A, its on-resistance is only 5.6 milliohms, and has been mass-produced.
Synchronous rectification technology improves the efficiency of secondary rectification, making it possible to produce low-voltage, high-current, and small-size communication power supply modules. For example, Synqor's Tera series is a standard half-brick module (2.3 inches x 2.4 inches), using synchronous rectification technology, its output voltage can be as low as 1.5V, the output current can be up to 60A, and the power density reaches 60W per cubic inch. Power module efficiency comparison using synchronous rectification technology and Schottky diode.
Application examples and technical advantages of synchronous rectification technology
Synchronous rectification technology improves power efficiency, but its significance is far more than that. It brings many new advances to the communication power module. Let's introduce the power module of Synqor Company as an example.
The communication power module produced by Synqor Company using synchronous rectification technology has achieved high efficiency (91%) due to reduced power consumption.
Due to the reduction in power consumption, a breakthrough in structure has been achieved, the heat sink has been eliminated, and a substrate-less structure has been adopted.
In the traditional communication power supply module, the base plate is a standard configuration, which is an important component to provide a heat dissipation path for installing a heat sink. At the same time, the power device is concentrated on the substrate and separated from the control circuit board to reduce the influence of the heating element on the control chip.
Synqor's power module eliminates the base plate and heat sink, and can achieve the required power under the same ventilation conditions, which is the result of using synchronous rectification technology. There are many significant advantages:
1. Due to the complex structure of the substrate, the installation and welding of the control circuit board, heat sink and magnetic core components all require manual labor, which increases the possibility of failure and reduces the productivity. The substrate structure requires that the power components and the substrate must maintain good insulation, which is one of the places where traditional communication power supplies are prone to failure.
2. After adopting synchronous rectification technology, an open structure without substrate can be used. In this way, it is more convenient to adopt new technologies such as planar transformers. The copper foil wiring on the multilayer circuit board is used as the coil. The magnetic core is directly embedded in the multilayer circuit board. The magnetic core has good heat dissipation and the copper foil on the multilayer circuit board is tightly coupled. The most important thing is that it can be automatically produced by advanced processing equipment, which realizes the automatic production of all power modules, which greatly improves productivity and reliability. Compared with traditional transformers, planar transformers can also achieve high power density and truly achieve miniaturization.
3. In addition, the substrate structure needs to be filled with insulating and thermally conductive materials, which increases the weight. The traditional power module with a base plate and a heat sink has large volume and weight, and poor seismic resistance, which hinders air circulation in the rack of communication equipment and reduces fan performance. The Synqor power module with synchronous rectification technology is an open structure with a height of only 10mm (0.4 inches), which saves rack space, facilitates ventilation, and facilitates the heat dissipation of other communication chips on the communication control board; the higher power density makes the power module It saves the space occupied on the communication control board; lower power consumption reduces the burden of the main power supply at the front end of the distributed system and saves the system investment.
4. After adopting synchronous rectification technology, the ability to resist electromagnetic interference (EMI) is enhanced. Due to the reduction of the substrate, the parasitic capacitance that originally existed between the substrate and the ground and between the substrate and the components is gone. The large common-mode interference caused by these parasitic capacitances also disappears, improving the performance of the power supply against electromagnetic interference.
Application prospect
Synchronous rectification technology meets the requirements of high efficiency and energy saving, adapts to the requirements of the new generation chip voltage, and has a very broad application prospect. However, only a few companies currently master the technology, and the cost of implementation is also very high, and there are still many applications that have not been explored. With the mass production of MOSFETs for synchronous rectification on the market, the emergence of dedicated driver chips, and the continuous improvement of control technology, synchronous rectification will become a mainstream power supply technology, gradually applied to a wide range of industrial production fields.
Mini PC
Are you tired on big and messy wires on traditional computer tower? If yes, mini pc bring clean and space saving working environment back to you. Whatever daily tasks, like browsing web pages, documents checking or making, online teaching or learning, entertainments, etc. Or heavy duty handling, like photshops, video or music editing, gaming, apps developing, engineering drawing, designing jobs, etc. You can always find a right pc mini intel at this store.
Mini PC Office is an most and popular series designed for those who mainly run WPS, photoshops, PR, email, entertainments, etc. Sometimes, also call it as mini pc officeworks or home assistant mini pc.
Mini Gaming PC comes with higher level processors, like intel i3, i5, i7 10th, 11th or 12th; bigger memory and storage, like 16GB or 32GB ram, 512gb up to 1tb. Of course, rich slots support linking with two or more monitors or devices.
Except mini pc windows 11, there are also All In One PC , Student Laptop, Gaming Laptop , Android Tablet, Yoga Laptop , etc.
Mini PC Windows 11,High Performance Mini PC,Mini PC DDR4,PC Mini Intel
Henan Shuyi Electronics Co., Ltd. , https://www.shuyipcs.com