小功率开关电源外文文献原稿和译文

外文文献原稿和译文

原稿

Introduction

S witching power supply work in high frequency, high pulse state, are analog circuits in a rather special kind. Cloth boards to follow the principle of high-frequency circuit wiring.

Layout

Pulse voltage connection as short as possible, including input switch connected to the transformer, output transformer to the rectifier tube cable. Pulse current loop as small as possible such as the input filter capacitor is returned to the transformer to the switch capacitor negative. Some out-ended output transformers are the output rectifier to the output capacitor back to transformer circuit X capacitor as close as possible to the input switching power supply, input lines should be avoided in parallel with other circuits, should be avoided. Y capacitor should be placed in the chassis ground terminal or FG connectors. A total of touch induction and transformer to maintain a certain distance in order to avoid magnetic coupling. Such as poor handling of feeling in between inductor and transformer plus a shield, over a number of EMC performance for power supply to the greater impact.

General the output capacitor can be used the other two a close rectifier output terminal should be close to, can affect the power supply output ripple index, two small capacitor in parallel results should be better than using a large capacitor. Heating devices to maintain a certain distance, and electrolytic capacitors to extend machine life, electrolytic capacitors is the switching power supply bottleneck life, such as transformers, power control, high power resistors and electrolytic to maintain the distance required between the electrolyte leaving space for heat dissipation , conditions permitting, may be placed in the inlet.

Control part to pay attention to: Weak signal high impedance circuit connected to sample the feedback loop as short as in the processing as far as possible avoid interference, the current sampling signal circuits, in particular the current control circuit, easy to deal with some unexpected bad The accident, which had some skill, now to 3843 the circuit example shown in Figure (1) Figure 1 better than Yu Figure 2, Figure 2 Zai full time by observing the current waveform oscilloscope Mingxian superimposed spikes, Youyuganrao limited flow ratio design Zhi Dian low, Figure 1 there is no such phenomenon, there are switch drive signal circuit, switch resistance should be close to the switch driver can switch the work to improve the reliability of this and the high DC impedance voltage power MOSFET driver characteristics. Second, routing

Alignment of current density: now the majority of electronic circuit board using insulated copper constitute tied. Common PCB copper thickness of 35μm, the alignment value can be obtained in accordance with 1A/mm experience the value of current density, the specific calculations can be found in textbooks. To ensure the alignment principles of mechanical strength should be greater than or equal to the width of 0.3mm (other non-power supply circuit board may be smaller minimum line width). PCB copper thickness of 70μm is also common in switching power supply, then the current density can be higher.

Add that, now Changyong circuit board design tool design software generally items such as line width, line spacing, hole size and so dry plate Guo Jin Xing parameters can be set. In the design of circuit boards, design software automatically in accordance with the specifications, can save time, reduce some of the workload and reduce the error rate.

Generally higher on the reliability of lines or line density wiring can be used double panel. Characterized by moderate cost, high reliability, to meet most applications.

The ranks of some of the power module products are also used plywood, mainly to facilitate integration of power devices such as transformer inductance to optimize wiring, cooling and other power tube. Good consistency with the craft beautiful, transformer cooling good advantage, but its disadvantage is high cost, poor flexibility,

only suitable for industrial mass production.

Single-sided, the market circulation of almost universal switching power supply using single-sided circuit board, which has the advantage of lower costs in the design and production technology are also taken some measures to ensure its performance. Single PCB design today to talk about some experience, as a single panel with low cost, easy-to-manufacture features, the switching power supply circuit has been widely used, because of its side tied only copper, the device's electrical connections, mechanical fixation should rely on the copper layer, the processing must be careful.

To ensure good performance of the mechanical structure welding, single-sided pad should be slightly larger to ensure that the copper and substrate tied good focus, and thus will not be shocked when the copper strip, broken off. General welding ring width should be greater than 0.3mm. Pad diameter should be slightly larger than the diameter of the device pins, but not too large, to ensure pin and pad by the solder connection between the shortest distance, plate hole size should not hinder the normal conditions for the degree of investigation, the pad diameter is generally greater than pin diameter 0.1-0.2mm. Multi-pin device to ensure a smooth investigation documents can also be larger.

Electrical connection should be as wide as possible, in principle, should be larger than the width of pad diameter, special circumstances should be connected in line with the need to widen the intersection pad (commonly known as Generation tears), to avoid breaking certain conditions, line and pad. Principle of minimum line width should be greater than 0.5mm.

Single-board components to be close to the circuit board. Need overhead cooling device to device and circuit board between the pins plus casing, can play a supporting device and increase the dual role of insulation to minimize or avoid external shocks on the pad and the pin junction impact and enhance the firmness of welding. Circuit board supporting the weight of large parts can increase the connection point, can enhance joint strength between the circuit board, such as transformers, power device heat sink.

Single-sided welding pins without affecting the surface and the shell spacing of the prior conditions, it can be to stay longer, the advantage of increased strength of

welded parts, increase weld area and immediately found a Weld phenomenon. Shear pin long legs, the welding force smaller parts. In Taiwan, the Japanese often use the device pins in the welding area and the circuit board was bent 45 degrees, and then welding process, its reasoning Ibid. Double panel today to talk about the design of some of the issues, in relatively high number of requests, or take the line density of the larger application environments using double-sided PCB, its performance and various indicators of a lot better than a single panel.

Two-panel pad as holes have been high intensity metal processing, welding ring smaller than a single panel, the pad hole diameter slightly larger in diameter than pins, as in the welding process solder solution conducive to penetrate through the top hole solder pad to increase the welding reliability. But there is a disadvantage if the hole is too large, wave soldering tin when the jet impact in the lower part of the device may go up, have some flaws.

High current handling of alignment, line width in accordance with pre-quote processing, such as the width is not enough to go online in general can be used to increase the thickness of tin plating solution, the method has a good variety of

1. Will take the line set to pad property, so that when the circuit board manufacturing solder alignment will not be covered, the whole hot air normally be tin plated.

2. In the wiring by placing pads, the pad is set to take in line shape, pay attention to the pad holes set to zero.

3. In the solder layer placed on line, this method is the most flexible, but not all PCB manufacturers will understand your intentions, needed captions. Place the line in the solder layer of the site will not coated solder tinning line several methods as above, to note that, if the alignment of a very wide all plated with tin in solder after the solder will bond a lot and distribution is very uneven, affecting appearance. Article tin can be used generally slender width in the 1 ~ 1.5mm, length can be determined according to lines, tin part of the interval 0.5 ~ 1mm.

Double-sided circuit board for the layout, the alignment provides a very selective, make wiring more reasonable. On the ground, the power ground and signal ground must be separated, the two to converge in filter capacitors, in order to avoid a

large pulsed current through the signal ground connection instability caused by unexpected factors, the signal control circuit grounding point as far as possible, a skill, as far as possible the alignment of the non-grounded wiring layer in the same place, the last shop in another layer of earth. Output line through the filter capacitors, the general first, and then to the load, input line must also pass capacitor, to the transformer, the theoretical basis is to ripple through trip filter capacitor.

Alignment change from a wiring layer to another wiring layer generally used hole connected, not through the pin pad device to achieve, because the plug in the device may be damaged when the relationship between this connection, there is current in every passage of 1A, at least two through-hole, through hole diameter is greater than the principle of 0.5mm, 0.8mm generally processed ensure reliability.

Cooling devices, in some small power supply, the circuit board traces can be and cooling, characterized by the alignment as generous as possible to increase the cooling area is not coated solder, conditions can even be placed over holes, enhanced thermal conductivity .

Aluminum plate by its own structure, has the following characteristics: very good thermal conductivity, single Mianfu copper, the device can only be placed in tied copper surface, can not open electrical connection hole so as not to place jumper in accordance with a single panel.

Aluminum plate is generally placed patch device, switch, the output rectifier heat conduction through the substrate to go out, very low thermal resistance, high reliability can be achieved. Transformer with planar chip structure, but also through substrate cooling, the temperature is lower than the conventional, the same size transformer with a large aluminum plate structure available output power. Aluminum plate jumper bridge approach can be used. Aluminum plate power are generally composed by the two PCB, another one to place the control circuit board, through the physical connection between the two boards is integrated.

As the excellent thermal conductivity of aluminum plate, in a small amount of manual welding more difficult, solder cooling too fast and prone to problems of a simple and practical way of existing, an ironing ordinary iron (preferably temperature regulation function), over and iron for the last, fixed, and temperature to 150 ℃and

above the aluminum plate on the iron, heating time, and then affix the components according to conventional methods and welding, soldering iron temperature is appropriate to the device easy to , is too high when the device may be damaged, or even copper strip aluminum plate, the temperature is too low welding effect is not good, to be flexible.

Recent years, with the multi-layer circuit board applications in switching power supply circuit, printed circuit transformer makes it possible, due to multilayer, smaller spacing also can take advantage of Bianya Qi window section, the main circuit board can be re- Add 1-2 formed by the multilayer printed coil to use the window, the purpose of reducing circuit current density, due to adopt printed coil, reducing manual intervention, transformers consistency, surface structure, low leakage inductance, coupling good . Open-type magnetic core, good heat dissipation. Because of its many advantages, is conducive to mass production, it is widely used. But the research and development of large initial investment, not suitable for small-scale health.

Switching power supply is divided into, two forms of isolation and non-isolated, isolated here mainly to talk about switching power supply topologies form below, non-specified, are to isolate the power. Isolated power supply in accordance with the structure of different forms, can be divided into two categories: a forward and flyback. Flyback transformer primary side means that when the Vice-edge conduction cut-off, transformer storage. Close of the primary, secondary side conduction, the energy released to the load of work status, general conventional flyback power multiplex, twin-tube is not common. Forward refers to the primary conduction in transformer secondary side while the corresponding output voltage is induced into the load, the direct transfer of energy through the transformer. According to specifications can be divided into conventional forward, including the single-transistor forward, Double Forward. Half-bridge, bridge circuits are all forward circuit.

Forward and flyback circuits have their own characteristics in the process of circuit design to achieve optimal cost-effective, can be applied flexibly. Usually in the low-power flyback can be adopted. Slightly larger forward circuit can use a single

tube, medium-power can use Double Forward circuit or half-bridge circuit, low-voltage push-pull circuit, and the half-bridge work in the same state. High power output, generally used bridge circuit, low voltage can be applied push-pull circuit.

Flyback power supply because of its simple structure, and to cut the size of a similar size and transformer inductance, the power supply in the medium has been widely applied. Presentation referred to in some flyback power supply can do dozens of watts, output power exceeding 100 watts would be no advantage to them difficult. Under normal circumstances, I think so, but it can not be generalized, PI's TOP chips can do 300 watts, an article describes the flyback power supply can be on the KW, but not seen in kind. Power output and the output voltage level.

Flyback power transformer leakage inductance is a critical parameter, because the power needs of the flyback transformer stored energy, to make full use of transformer core, the general must be open in the magnetic circuit air gap, the aim is to change the core hysteresis back line of the slope, so that transformers can withstand the impact of a large pulse current, which is not core into saturation non-linear state, the magnetic circuit in the high reluctance air gap in the state, generated in the magnetic flux leakage is much larger than completely closed magnetic circuit .

Transformer coupling between the first pole is the key factor determining the leakage inductance, the coil to be very close as far as possible the first time, the sandwich can be used around the law, but this would increase the distributed capacitance transformer. Use core as core with a long window, can reduce the leakage inductance, such as the use of EE, EF, EER, PQ-based EI type magnetic core effective than good.

The duty cycle of flyback power supplies, in principle, the maximum duty cycle of flyback power supply should be less than 0.5, otherwise not easy loop compensation may be unstable, but there are some exceptions, such as the U.S. PI has introduced the TOP series chip can work under the conditions of duty cycle is greater than 0.5.

Duty cycle by the transformer turns ratio to determine former deputy side, I am an anti-shock view is, first determine the reflected voltage (output voltage reflected through the transformer coupling the primary voltage value), reflecting a

certain voltage range of voltage increase is duty cycle increases, lower power loss. Reduce the reflected voltage duty cycle decreases, increases power loss. Of course, this is a prerequisite, when the duty cycle increases, it means that the output diode conduction time, in order to maintain output stability, more time will be to ensure that the output capacitor discharge current, the output capacitor will be under even greater high-frequency ripple current erosion, while increasing its heat, which in many circumstances is not allowed.

Duty cycle increases, change the transformer turns ratio, transformer leakage inductance will increase, its overall performance change, when the leakage inductance energy large enough, can switch to fully offset the large account space to bring low-loss, no further increase when the meaning of duty, because the leakage inductance may even be too high against the peak voltage breakdown switch. Leakage inductance as large, may make the output ripple, and other electromagnetic indicators deteriorated. When the duty hours, the high RMS current through the switch, transformer primary current rms and lowered the converter efficiency, but can improve the working conditions of the output capacitor to reduce fever. How to determine the transformer reflected voltage (duty cycle)

Some netizens said switching power supply feedback loop parameter settings, work status analysis. Since high school mathematics is rather poor, "Automatic Control Theory," almost on the make-up, and for the door is still feeling fear, and now can not write a complete closed-loop system transfer function, zero for the system, the concept of feeling pole vague, see Bode plot is only about to see is a divergence or convergence, so the feedback compensation can not nonsense, but there are a number of recommendations. If you have some mathematical skills, and then have some time to learn then the University of textbooks, "Principles of Automatic Control" digest look carefully to find out, combined with practical switching power supply circuit, according to the work of state for analysis. Will be harvested, the Forum has a message, "coach feedback loop to study the design, debugging," in which CMG good answer, I think we can reference.

Then today, on the duty cycle of flyback power supply (I am concerned about the reflected voltage, consistent with the duty cycle), the duty cycle with the

voltage selection switch is related to some early flyback switching power supply using a low pressure tube, such as 600V or 650V AC 220V input power as a switch, perhaps when the production process, high pressure tubes, easy to manufacture, or low-pressure pipes are more reasonable conduction losses and switching characteristics, as this line reflected voltage can not be too high, otherwise the work order to switch the security context of loss of power absorbing circuit is quite impressive.

Reflected voltage 600V tube proved not more than 100V, 650V tube reflected voltage not greater than 120V, the leakage inductance voltage spike when the tubes are clamped at 50V 50V working margin. Now that the MOS raise the level of manufacturing process control, flyback power supplies are generally used 700V or 750V or 800-900V the switch. Like this circuit, overvoltage capability against a number of switching transformer reflected voltage can be done a bit higher, the maximum reflected voltage in the 150V is appropriate, to obtain better overall performance.

TOP PI's recommendation for the 135V chipset with transient voltage suppression diode clamp. But his evaluation board generally reflected voltage to be lower than the value at around 110V. Both types have their advantages and disadvantages:

Category: shortcomings against over-voltage, low duty cycle is small, a large pulse current transformer primary. Advantages: small transformer leakage inductance, electromagnetic radiation and low ripple index higher switch loss, the conversion efficiency is not necessarily lower than the second.

The second category: a large number of shortcomings of power loss, a large number of transformer leakage inductance, the ripple worse. Advantages: Some strong against over-voltage, large duty cycle, lower transformer losses and efficiency higher.

Reflected voltage flyback power supply with a parameter related to that is the output voltage, output voltage, the lower the larger the transformer turns ratio, the greater the transformer leakage inductance, switch to withstand higher voltage breakdown switch is possible to absorb power consumption is higher, has the potential to permanently absorb the circuit power device failure (particularly with transient

voltage suppression diode circuits). In the design of low-voltage low-power flyback power output optimization process must be handled with care, its approach has several:

1, using a large core of a power level lower leakage inductance, which can improve the low-voltage flyback power conversion efficiency, reduce losses, reduce output ripple and improve multi-output power of the cross regulation in general is common in household appliances with a switch power, such as CD-ROM drive, DVB set-top boxes.

2, if the conditions were not increased core, can reduce the reflected voltage, reducing the duty cycle. Reduce the reflected voltage can reduce the leakage inductance but may reduce the power conversion efficiency, which is a contradiction between the two, must have an alternative process to find a suitable point, replace the transformer during the experiment can detect the transformer original side of the anti-peak voltage, peak voltage to minimize the anti-pulse width, and magnitude of the work safety margin increase converter. Generally reflected voltage 110V when appropriate.

3, enhance the coupling, reducing losses, the introduction of new technologies, and the routing process, transformers to meet the security specifications will between the primary and secondary side to insulation measures, such as pad tape, plus side air insulation tape. These will affect the performance of transformer leakage inductance, the reality can be used in production around the primary winding secondary wrapping method. Or sub-system with a triple insulated wire wound to remove the insulation between the initial level, can enhance the coupling, even use wide copper winding.

The article refers to low voltage output is less than or equal to 5V output, as this type of small power supply, my experience is that the power output of more than 20W output can use a forward, get the best value for money, of course, this is not the right decision , and personal habits, relationship between the application environment, the next time to talk about the flyback power supply with a magnetic core, magnetic circuit air gap opening some understanding, I hope you receive adequate guidance.

Flyback power transformer core magnetization state at work in one way, it

needs to open the air gap magnetic circuit, similar to the pulsating direct current sensor. Part of the magnetic coupling through the air gap. Why I understand the principle of open air gap as follows: As the power ferrite also has a similar rectangle of the operating characteristics (hysteresis loop), operating characteristics curve in the Y-axis magnetic induction (B), now the general production process saturation point in 400mT above, the general value in the design of this value should be more appropriate in the 200-300mT, X-axis magnetic field strength (H) the value of current intensity is proportional to the magnetization. Open magnetic circuit air gap equal to the magnetic hysteresis loop to the X axis tilt, in the same magnetic induction intensity, can withstand a greater magnetizing current, equivalent to core store more energy, this energy cut-off switch When spilled into the load through the transformer secondary circuit, flyback power core to open the air gap is twofold. One is to transfer more energy, and the second to prevent the core into saturation.

Flyback Power Transformer magnetization state in one way, not only to pass through the magnetic coupling energy, is also responsible for input and output isolation voltage transform multiple roles. Therefore, the treatment gap need to be very careful, the air gap leakage inductance can become too large, increase the hysteresis loss, iron loss, copper loss increases, affecting the power of the whole performance. Air gap is too small has the potential to transformer core saturation, resulting in damage to power.

The so-called flyback power supply is continuous and discontinuous mode transformer working conditions, working in full load condition in the power transformer complete transfer, or incomplete transmission mode. General design of the working environment, conventional flyback power supply should work in continuous mode, this switch, circuit loss are relatively small, and can reduce the stress of work input and output capacitors, but that there are some exceptions.

Requires in particular that: As the characteristics of the flyback power supply is also more suitable for design into a high-voltage power supply, and high-voltage power transformers generally work in discontinuous mode, I understand the need for as high voltage power supply output voltage of the rectifier diodes. Because of the manufacturing process characteristics, high-tension diode, reverse

recovery time is long, low speed, the current continuous state, the diode has a positive bias in the recovery, reverse recovery energy loss is very large, is not conducive to converter performance increase, ranging from reduced conversion efficiency, rectifiers, severe fever, weight is even burnt rectifier. As in the intermittent mode, the diode is reverse biased under zero bias, loss can be reduced to a relatively low level. Therefore, high voltage power supply work in discontinuous mode, and the frequency can not be too high.

Another type of flyback power supply work in the critical state, the general type of power supply work in FM, or FM-width-modulated dual-mode, a number of low-cost self-excitation power (RCC) is often used this form in order to ensure stable output transformer As the operating frequency, output current or input voltage change, close to the fully loaded transformer is always maintained at between continuous and intermittent, this power is only suitable for small power output, otherwise the handling characteristics of electromagnetic compatibility will be a headache.

Flyback switching power supply transformer should work in continuous mode, it required relatively large winding inductance, of course, is to some extent continuous, excessive pursuit of absolute continuity is not realistic, may need a great core, very much coil turns, accompanied by a large leakage inductance and distributed capacitance, worth the trouble. So how does this parameter to determine, through repeated practice, and analysis of peer design, I think, in the nominal voltage input, the output reached 50% and 60% transformer from intermittent, continuous state of transition to more appropriate. Or at the highest input voltage state, the full output, the transformer can transition to the continuous state on it

译文

介绍

开关电源状态，电源工作在高频率，高脉冲的模拟电路的一个比较特殊的一种。布板布线原则遵循高频电路。

布局

脉冲电压连接尽可能短，包括输入开关连接到变压器，输出变压器的整流管电缆。脉冲电流回路尽可能小，如输入滤波电容的负返回变压器开关电容器。一些外端输出变压器是输出整流器的输出电容回变压器电路X关闭电容器尽可能输入开关电源，输入线应避免与其他电路中平行，应该避免。Y电容应放置在机箱的接地端子或fg连接器。一个变压器总的触摸感应，并保持一定的距离，以避免磁耦合。如处理不当影响较大的感觉电感器和变压器之间加一屏蔽，过一个数字的EMC性能的电源。

总的输出电容可以使用的其他两个紧密整流器输出端应接近，可能会影响电源的输出纹波指标，结果两个小电容并联电容器应该比使用大。暖气设备要保持一定的距离，电解电容，延长机器寿命，铝电解电容器是开关电源的瓶颈生活热，如变压器，电源控制，高功率电阻器和电解空间的距离为维持电解质之间需要离开耗散，条件允许的话，可能被放置在入口。

控制部分要注意：高阻抗电路连接到样品的反馈回路短弱信号处理中尽量避免干扰，电流采样信号的电路，特别是电流控制电路，容易处理一些意想不到坏的事故，其中有一些技巧，现在3843的电路示例如图（1）图1 2比于图，图2再叠加尖峰全职通过观察电流波形示波器暹，Youyuganrao有限的流量比设计志滇低，图1有没有这样的现象，有开关驱动信号的电路，开关电阻应接近开关驱动器可以切换工作，提高可靠性的特点，这和高直流阻抗电压功率MOSFET驱动器。

路径

对准电流密度：现在大部分的铜电子绝缘电路板使用构成并列。常见的PCB 铜层厚度35μm，对齐值可1A/mm经验，按照目前的密度值，具体计算可以发现教科书。为了确保机械强度的对齐原则应大于或等于0.3毫米宽（其他非电源电路板可能会更小的最小线条宽度）。PCB的厚度为70μm铜也是常见的开关电源

供应，则电流密度可以更高。

补充一点，现在长永电路板设计工具设计软件性参数，一般的项目，如线宽，线间距，孔大小等干板过几嗯可以设置。在电路板的设计，软件设计规格自动根据，可以节省时间，减少工作量，减少一些错误率。

一般布线的密度更高的可靠性线或行可用于双面板。其特点是价格适中，可靠性高，能满足大多数应用。

产品的电源模块队伍的一些也被用于胶合板，主要是方便设备的集成，如电力变压器电感优化布线，制冷等行业的功率管。良好的一致性与工艺美观，变压器冷却良好的优势，但其缺点是成本高，弹性差，只适合于工业化大生产。

单面，电力供应市场上流通使用的几乎是普遍的切换单双面电路板，它具有技术优势和生产成本较低的设计，也采取了一些措施，以确保其性能。

为了保证焊接结构件的机械性能良好，单面垫应该再大一点，以确保良好的铜和基材并列焦点，因而不会感到震惊时，铜带，折断。一般焊接环宽度应大于0.3毫米。焊盘直径应略大于销直径的设备，但不太大，确保了最短的距离引脚和焊盘之间的连接由焊料，板孔尺寸应不妨碍调查的正常程度的条件，垫直径一般大于销直径0.1 - 0.2mm的。多针装置，确保顺利调查文件也较大。

电气连接应尽可能广泛，原则上应直径大于垫宽度，特殊情况应连接线的需要扩阔路口垫（通常称为泪水代），以避免破坏某些条件，线，垫。最小线条宽度原则应大于0.5毫米。

单板组件接近电路板。需要冷却设备到设备的开销和电路板之间加套管针，可以起到支撑装置，提高保温的双重作用，尽量减少或避免外部冲击的影响交界的垫脚，提高了焊接的坚定性。电路板支持点的大部分重量可以增加连接，可以提高连接强度板，如变压器之间的电路，功率器件的散热片。

间距的先决条件单面焊脚没有外壳表面和影响，它可以延长逗留时间，增加了区位优势的焊接部位的强度，提高焊接，立即找到了焊缝的现象。剪脚长的腿，焊接力较小的部分。在台湾，日本人经常使用的焊接领域的器件引脚和电路板中的弯曲45度，然后焊接过程中，其理由同上。双面板今天谈论的问题，设计了一些，在相对 ??高的请求数，或采取双面PCB的线路密度的两倍大的应用环境使用，其性能和各项指标单面板的好多了比。

双面板垫象洞已经高强度的金属加工，焊接环针小于单面板，焊盘孔直径稍大的直径比，因为在焊接过程中焊垫的解决方案有利于穿透洞上方焊增加焊接

的可靠性。但是有一个缺点，如果孔太大，波峰焊锡时，该设备的一部分，在射流冲击下可能会了，也有一些缺陷。

高电流处理对齐，宽度根据预先报价处理，如宽度不够上网一般可用于增加锡层厚度的电镀液，该方法具有良好的多种

1.将采取垫财产线设置为，这样，当电路板制造焊接校准将不包括在内，整个热空气通常是镀锡。

2.在布线放置垫，垫被设定为参加线条造型，注意垫零洞设置为。

3.在网上放置一层焊锡，这种方法是最灵活的，但不是所有的PCB制造商能够理解你的意图，需要说明文字。广场上面的几种方法行线焊的部位涂一层锡镀锡不会要注意的是，如果所有路线很广锡焊料镀后焊将债券很多，分布极不均匀，影响美观。可使用1?1.5mm的宽度一般在细长，长度可根据确定的线路，锡部分区间为0.5?1mm的

双面电路板的布局，调整提供了一个非常有选择性的，使布线更为合理。在地面上，电源地和信号地必须分开，以衔接的两个滤波电容，以避免大电流脉冲因素意外地通过信号由连接不稳定造成的，信号控制电路的接地点尽可能可能，一种技能，尽可能地排列在另一店铺层非接地布线层中的最后一个，同一个地方。输出电容线通过过滤器，一般先，然后到负载，输入行还必须通过电容，在变压器的理论基础是波及整个行程滤波电容。

电压反馈取样，以避免高电流通过采样点的反馈电压调整的必须是最外围功率输出，以增加目标机负载效应。

对准变化从一个布线层布线层到另一个洞一般用于连接实现的，而不是通过密码键盘设备，因为设备插上时，可能会损坏连接之间的关系这一点，在每一个有电流通过的第1A，在至少有两个通孔，通孔直径大于0.5毫米的原则，一般为0.8mm 处理确保可靠性。冷却装置，在一些小型电源，电路板走线可以和冷却，对齐特点是尽可能慷慨，以增加散热面积是不带涂层焊接，条件，甚至可以放置在洞，增强导热性。

铝结构钢板通过自己的，具有以下特点：非常良好的热传导性，单棉服铜，设备只能放置在铜表面的束缚，无法打开电气连接孔，以便不按照单一面板跳线放置在。

铝合金板一般放置补丁设备，开关，输出整流器基板热传导通过走出去，非常低热阻，可靠性高，可以实现的。结构与平面变压器芯片，而且还通过面板冷却，

温度低于常规，铝板结构相同大小变压器一大输出功率。铝板跳线引桥都可以使用。铝基板电源一般由两间印刷电路板，一个又一个地方的控制电路板，通过集成板之间的物理连接两个。

由于优良的热导率铝板焊接，手工少量更加困难，焊料冷却过快，容易出现问题的铁），过去，一个简单实用的方法对现有的，将熨烫普通铁（最好的温度调节功能最后，固定，温度至150℃以上的铁铝板上，加热时间，然后贴上的组件按常规方法和焊接，电烙铁温度适当的设备容易，过高时该设备可能会损坏，甚至铜带铝板，温度太低焊接效果并不好，要灵活。

近年来，随着多层电路板应用在电源电路开关电源，印刷电路变压器使得有可能，由于多层，小间距也可以部分利用Bianya齐窗口，主电路板可重新添加一良好的耦合-2所形成的多层印刷线圈使用视窗电路，减少电流密度的目的，由于采用印刷线圈，减少人工干预，变压器的一致性，表面结构，低漏感。开放型磁芯，散热性好。因为它具有很多优点，有利于大规模生产，它被广泛使用。但研究和开发的大型初始投资，而不是健康适合小规模的。

开关电源分为两个独立形式的隔离和非孤立这里主要谈谈开关电源拓扑结构形式下，非指定的隔离电源。供应隔离电源按照不同的结构形式可分为两类：一激和反激。回扫变压器初级端意味着当副边导通截止，变压器存储。关闭的小学，中学侧传导，释放的能量功率反激式多路给负载的工作状态，一般常规，双管是不常见的。远期是指二次侧主变压器传导而相应的输出电压互感器诱导为负载，通过直接传输能量。按规格可分为常规推进，包括单管正激，双管正激。半桥，全桥电路是向前电路。

激和反激电路具有电路设计他们自己的进程的特点，在达到最佳的成本效益，能灵活运用。反激式通常是低功率可以被采纳。稍大激电路可以使用单管，中等功率可以使用双管正激电路或半桥电路，低电压推挽电路，以及在同一国家的半座桥。

反激式电源供应器结构简单，因为它，并减少电感的大小，同样的变压器，电源供应器中的介质已被广泛应用。讲中提到的一些反激式电源供应器可以做到几十瓦，输出功率超过100瓦的优势将不会对他们很难。在正常情况下，我认为是这样，但不能一概而论，有价证券的TOP芯片可以做到300瓦，文章介绍了反激式电源供应器可以在千瓦，但不是那种看到英寸输出功率和输出电压水平。

反激式电源变压器的漏感是一个关键参数，因为电源，回扫变压器需要储存的能

量，使变压器磁芯充分利用，一般必须打开缺口磁路空气，其目的是改变核心迟滞回线的斜率，使变压器能承受状态影响的大型脉冲电流，这是进入不是核心饱和非线性的，是在国家磁路磁阻的差距，在高空气，泄漏产生的磁通量多大于全封闭的磁路。

第一杆变压器之间的耦合是关键因素决定的漏感，线圈是非常接近尽可能第一时间，夹心法可用于周围，但是这会增加变压器的分布电容。使用Core核心，以长窗，可以有效降低漏感比好，核心使用，如电子工程，英法，能效比，电能质量为基础的磁EI型。

这些电源占空比反激，原则上，反激式电源的最大占空比应小于0.5，否则不容易的环路补偿可能是不稳定的，但也有一些例外的TOP系列，如美国的PI推出芯片可以工作在占空比条件下大于0.5。

务变周期的圈数比，以确定原副边，我是抗休克的看法是，首先确定反射电压（输出电压值反映通过变压器耦合的初级电压），反映了一定的电压增加电压范围为占空比的增加，较低的功率损耗。降低反射电压占空比减小，提高了功率损耗。当然，这是一个先决条件，当占空比增大，这意味着输出二极管导通时间，以保持输出稳定，更多的时间将是保证输出电容放电电流，输出电容将受到更更大的高频纹波电流的侵蚀，同时增加它的热量，这在很多情况下是不允许的。

占空比增大，改变变压器匝数比，变压器漏感会增加，其整体性能的变化，当漏感能量足够大时，可以切换到完全抵消大客户空间，使损耗低，没有进一步上升的含义责任，因为漏感，甚至可能过于对峰值开关高电压击穿大量泄漏电感一样，可能使输出纹波和其他电磁指标恶化。当值小时，RMS和高RMS电流通过开关，变压器初级电流转换器的效率降低，但可以提高，以减少发热的工作条件的输出电容。如何确定变压器反射电压（占空比）有网民说，开关电源反馈回路参数设置，工作状况分析。从高中数学是比较差，“自动控制理论”，几乎在化妆，就向门口仍能感受到恐惧，现在还没有写闭环系统传递函数，零系统中的一个完全封闭的，在感觉极模糊的概念，只看到波特图是即将看到的是一个发散或收敛，所以不能胡说反馈补偿，但也有一些建议的。如果你有一些数学技能，然后有一段时间来学习，然后教科书的大学“自动化控制原理”消化仔细找出来，结合实际电路开关电源，根据分析的工作状态。会有所收获，论坛有一个消息，“教练的反馈回路，以研究设计，调试，”中保康联很好的答案，我认为我们可以参考一下。