Power adapter PCB layout and wiring design.india plug charger

　　In the early power adapter PCB design tools, there were special layout software for layout, and there was also special wiring software for wiring. There was no connection between the two. With the high-density single chip, high-density connector, and microvia of the ball grid array package The application of built-in technology and 3D board in PCB design, layout and routing has become more and more integrated, and has become an important part of the design process. Software technologies such as automatic layout and free-angle routing have gradually become solutions to this type of high integration The important method of the problem is to use such software to design a manufacturable circuit board within the specified time frame. In the current situation where the time to market for power adapter products is getting shorter and shorter, manual wiring is extremely time-consuming and untimely. Therefore, the layout is now required ､Wiring tools should have automatic wiring functions to quickly respond to market requirements for product design. Design constraints

　　Due to the consideration of high-density design factors such as electromagnetic compatibility (EMC) of the adapter and electromagnetic interference, crosstalk, signal delay, and differential pair wiring, the layout and wiring conditions are increasing every year. For example, a few years ago, the general power circuit The board only needs 6 differential pairs for wiring, but now it needs 600 pairs. It is impossible to rely on manual wiring for a certain period of time to achieve these 600 pairs of wiring. Therefore, automatic wiring tools are indispensable although they are different from a few years ago. Compared with the current design, the number of nodes (Net) has not changed much, but the complexity of the silicon chip has increased, but the proportion of important nodes in the design has greatly increased.

　　Of course, for some particularly important nodes, the layout and wiring tools are required to be able to distinguish, but there is no need to restrict each pin or node. (1) Free-angle wiring As the functions integrated on the monolithic device become more and more The number of output pins has also greatly increased, but the package size has not been expanded accordingly. Coupled with the limitation of pin spacing and impedance factors, such devices must use a finer line width. The overall reduction of the adapter product size Small also means that the space for layout and wiring is greatly reduced. In some electronic products, the size of the bottom board is almost the same as the size of the components on it, and the board area occupied by the components is as high as 80%.

　　Some high-density component pins are staggered, even if a tool with a 45° routing function is used, automatic routing cannot be performed. Although the 45° routing tool can perfectly handle some line segments that are exactly 45°, the free-angle routing tool has Greater flexibility, and can maximize the wiring density.

　　The pull-tight function enables each node to be automatically shortened after wiring to meet the space requirements. It can greatly reduce the signal delay, while reducing the number of parallel paths, helping to avoid crosstalk. Although the free angle design is manufacturable Performance, and performance is good, but this design will cause the motherboard to look less beautiful than the previous design. 2) High-density devices are available.

　　The latest high-density system-on-chips are packaged in BGA or COB, and the pin pitch is increasingly reduced. The ball pitch has been as low as 1mn, and will continue to decrease, making it impossible for the package signal lines to be led out by traditional wiring tools. Currently there areThere are two ways to solve this problem: one is to lead the signal line from the lower layer through the hole under the ball; the other is to find a lead channel in the ball grid array using very fine wiring and free-angle wiring. For this high-density device In other words, it is the only feasible way to use a wiring method with a very small width and space. Only in this way can a higher yield rate be guaranteed. Modern wiring technology also requires these constraints to be automatically applied. Use: The free wiring method can reduce the number of wiring layers , Reduce product cost. At the same time, it also means that some ground layers and power adapter layers can be added to improve signal integrity and EMC performance while the cost remains the same.

　　An electronic device with excellent performance, in addition to selecting high-quality components and reasonable circuits, the correct structural design of the PCB component layout and electrical wiring direction is a key issue that determines whether the electronic device can work reliably. The circuit of components and parameters will produce different results due to the different component layout design and electrical wiring direction, and the results may be very different. Therefore, it is necessary to correctly design the structure of the PCB component layout and correctly select the wiring direction and The three aspects of the process structure of the overall electronic equipment are considered together. A reasonable process structure can not only eliminate the noise interference caused by improper wiring, but also facilitate the installation, debugging and maintenance in production.

　　PCB is the support of circuit components and devices in power adapters, providing electrical connections between circuit components and devices. With the rapid development of electronic technology, the density of PCBs is getting higher and higher. The quality of PCB design has a great impact on the ability to resist interference. Therefore, the general principles of PCB design must be observed when PCB design is carried out, and the requirements of anti-interference design must be complied with. In order to obtain the best performance of electronic circuits, the layout of components and the layout of wires are very important. Due to the excellent quality "Structure" does not have a strict "definition" and "mode". Therefore, the structure of each type of electronic equipment must be based on specific requirements (electrical performance, overall structure installation and panel layout requirements), adopt corresponding structural design plans, and Compare and modify several feasible design schemes repeatedly. The wiring structure of the printed board power adapter and ground bus is selected because there are many similarities and differences in the design and wiring method of the component layout of the analog circuit and the digital circuit. In the analog circuit Due to the existence of the amplifier, the very small noise voltage generated by the wiring will cause serious distortion of the output signal; in the digital circuit, the TTL noise tolerance is 0.4~0.6V, and the CMOS noise tolerance is 0.3~0.45 times of Vc, so The digital circuit has strong anti-interference ability. The reasonable choice of good power and ground bus mode is an important guarantee for the reliable operation of electronic equipment. Quite a lot of interference sources are generated through the adapter and the ground bus, among which the noise interference caused by the ground wire maximum.

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