“When designing a power supply, power supply design engineers used to spend a lot of time in selection and circuit design and evaluation. Because power supply design involves EMI, efficiency, performance and cost, and the design cycle is constantly shortened, it is difficult for engineers to have sufficient time to choose a product that is most suitable for them.
When designing a power supply, power supply design engineers used to spend a lot of time in selection and circuit design and evaluation. Because power supply design involves EMI, efficiency, performance and cost, and the design cycle is constantly shortened, it is difficult for engineers to have sufficient time to choose a product that is most suitable for them.
Although there are various powerful evaluation tools and software offline, the offline tools are relatively complex and lack effective and timely updates. Nowadays, with the rise of cloud computing, major power supply manufacturers have developed online design tools based on the network, which can greatly simplify the time for engineers to select and evaluate in the early stage of power supply design, and enhance the design efficiency of engineers.
In the following, we select the online design tools of three power supply design manufacturers, and use actual cases to evaluate the characteristics of each.
We are going to make a flyback power supply with an input of 85-265V and an output of 5V/2A, and do a horizontal evaluation. This article only represents personal opinions. Considering the different applications, I hope readers can try it for themselves.
ROHM Online Design Tool
The first thing we focus on is ROHM’s online design tool: ROHM AC/DC Designer.
Click Product Information, IC, Power Management, and AC/DC Converter in the navigation bar of ROHM’s official website to find the tool. Enter the parameters we need in the pink box in the figure below, and click the Search button to enter the next parameter search.
As the name suggests, since it is a parameter search, users can choose to input their own filter conditions to get a more accurate target design, or choose not to input any parameters to give themselves more choices.
Continue to browse down, you can see a list of eligible devices filtered according to parameter settings and filter conditions, and select the device that meets your design needs. To this end, we choose a device with overvoltage protection (restart), BM2P014, click the red button in the list, and the dialog box shown in the figure below will pop up. Continue to click the Design button to get the design result.
The design result is displayed to the user as a schematic diagram by default, and the user can select “Calculation Reset”, “BOM List”, “Transformer Specifications”, “Design Results”, “Download Design Options” according to their own needs, and view and download the corresponding documents. ,Aided design.
To sum up, the overall experience of using ROHM’s online design software: easy to operate, a simple design scheme of peripheral components can be generated in a few simple steps, and users can design a stable and reliable power supply in combination with the data sheet.
Next, let’s experience TI WEBENCH® Power Designer.
WEBENCH is relatively easy to find. Through the navigation bar of TI’s official website, click Design Resources and WEBENCH Power Designer in turn to enter the design interface. It should be noted that: to use this tool, users need to register a myTI account in advance.
Different from ROHM tools on the product page, WEBENCH has an independent tool interface, and you can easily switch languages through the left navigation bar.
In the input column in the upper left corner, select the power supply type as AC, and set the parameters according to the design requirements: input voltage range, output voltage, output current, and in the design considerations, select balance, low cost, high efficiency, small size, and then click the VIEW DESIGNS button to enter the design results page.
According to our design requirements, we obtained 114 reference designs, from which the following schemes were selected: schemes with an efficiency of 82.8%, Flyback, and UCC28740.
In terms of component information provision, WEBENCH is very friendly. By clicking on any component in the schematic diagram, users can see detailed parameters and specifications. At the same time, alternative options are also provided, and users can find alternative devices from other semiconductor manufacturers.
Finally, click Export to output the schematic, BOM, diagram and operating values of the solution we need to assist in the design.
To sum up, the overall feeling of using TI WEBENCH: the design scheme is more user-friendly, the logo is clear, and it is easy to use. It is relatively easy for users to design a switching power supply that meets the requirements; the component parameters of the schematic diagram are provided in great detail, allowing users to clearly know the parameters of each device. The output design documents and test data, such as: current and temperature rise, output current and efficiency, output current and duty cycle curves, are very complete; there are many design cases, and there is a large selection space.
Finally, let’s experience PI Expert. Since PI itself focuses on switching power supply solutions, users can find the design tool on the PI homepage, and the bilingual interface in Chinese and English makes it more convenient for users to use. It should be noted that: to use this tool, users need to register a PI account in advance.
We click Start Design to enter the design interface.
The first part on the left is the device list, and the user can select the product series according to the familiarity of PI products. The second part in the middle is function screening. Users can ask the system to recommend design solutions according to their own application scenarios. The third part on the right is the button to open the subsequent PI Expert design tool. The 4th part on the right is the “PI XLS” high frequency transformer design button. Let’s take the PI TinySwitch series as an example, click PI Expert to open our design.
The first step is to set the options
The parameters in the box can be selected by the user, we choose DIP package, frequency of 132kHz, adapter type (in order to adapt to poor heat dissipation or high temperature environment, users can choose an open design according to their needs), and the feedback method is secondary TL431 , click “next” to set the input voltage on the pop-up page, we choose General. Proceed to the next step.
Next, enter the output voltage setting interface, click the “ADD” button, a dialog box will pop up, and the user can set the output voltage, current parameters, and output voltage accuracy. This part can allow multiple output voltages, which is convenient for users with multiple output voltages. The total peak power, working mode, continuous power, etc. can also be set below. Here we select the CV mode and click “NEXT” to enter the next step.
In the design setting interface, set the design name, default component set, start item, shield layer (without shield by default) and unit (default US standard).
After clicking “finish”, the TinySwitch series will pop up with a total of six solutions
After “OK” confirmation, six options pop up as follows:
We choose the first option and confirm.
The pop-up interface is relatively simple, and the schematic diagram can be zoomed in and out in real time through the mouse wheel.
The “1” column in the left test is the parameter setting box, such as: input and output voltage modification, transformer design, clamp absorption circuit design, input and output filter circuit, loop compensation design, etc., users can configure according to their own conditions. As shown in the figure below, it is a design modification of the clamp circuit.
After we click on the clamp circuit, the interface pops up, and the user can easily choose the absorption method of the clamp circuit. We choose the “RCD absorption” method, the schematic diagram quickly follows the changes, and the pins of the schematic transformer are also numbered.
The middle section contains schematics, design results, board layout, BOM, transformer construction, and design considerations. The design result output helps users to proofread and confirm the design parameters.
PCB layout minimizes the difficulty of user design, and quickly completes the design of layerout.
Transformer design includes electrical characteristics schematic diagram, winding structure diagram, winding description and electrical characteristics test rules and other information.
In addition, on the right side of the schematic, PI also provides reference materials such as data sheets, design examples, and application notes for related devices. There is also a design warning prompt on the upper right, which can find problems in the design in real time. Finally, we click the File drop-down menu to output the design results.
Next, we will experience the design function of PI Xls high frequency transformer. This option is more suitable for users who have some experience in power supply design. It is simpler and easier to change relevant parameters in transformer design, allowing designers to experience the effect of “real-time transformer optimization WYSIWYG”.
The transformer design page is divided into two parts. The first part on the left is the high-frequency transformer parameter design menu, which can edit the physical parameters of the transformer. The second part on the right is the main part, which mainly adjusts the electrical design of the high-frequency transformer.
For example, we select “Pin Assignment Options” and the user can edit the pins assigned to the transformer.
Sometimes, in order to have better EMC performance, the ordinary design may not meet our requirements. At this time, we need to add a shielding layer to further improve the characteristics of the high-frequency transformer. We can do this by selecting the option “Block” that pops up to tick and confirm.
After confirmation, the transformer has two more shielding layers, which is very beneficial to improve electromagnetic compatibility.
The main part on the right is the design box about the electrical parameters of the transformer. The gray part needs to be filled in by the user. If it is not filled in, the system will design according to the default value.
The electrical parameters of this example (AC-85-265V input: 5V/2A output) are exactly what we want. Here we directly output the transformer parameters. “Transformer structure” details the electrical schematic diagram of the high-frequency transformer, winding structure diagram, winding manufacturing instructions, materials, electrical test items, etc., what you see is what you get.
Regarding the “transformer parameter” option, there is a processing problem in the high-frequency transformer of the flyback switching power supply. PI also gives the user a clear data – air gap. This parameter is generally designed in the range of 0.1-0.3mm. It is more suitable, mainly to prevent Magnetic saturation and used to adjust the primary winding inductance. If the air gap smaller than 0.1mm is too small, it is difficult to make it. If the air gap is too large, the magnetic resistance of the magnetic core increases, the efficiency of the transformer decreases, and it is easy to cause audio noise.
“PIXLs table” mainly describes the load curve over the full voltage range
Attached is the output of the transformer design data for this example.
In summary, we also summarize the experience of PI Expert. The extremely detailed design process gives engineers great design flexibility. An original design that is closer to the final design is produced. You can even directly use the transformer, BOM, and schematic files generated by it for prototyping. Just as PI’s official slogan: You only need to prioritize, and leave the optimization of efficiency, performance and cost to PI Expert. PI gives engineers maximum optimization flexibility, supports a range of adjustable parameters, and can choose to prioritize optimization by cost, efficiency, core volume, or thermal performance. The specific design is automatically calculated by PI based on the power know how accumulated over the years.
In addition to this, PI Expert allows the user to limit the optimization engine to optimize according to the user’s preference according to the range of some specific parameter values. This feature is useful, for example, when the user wants to use the power value given by the engine, but needs to make a careful decision during the design process. For example, the engine may be asked to examine the optimized route, but limit VOR and/or KP to a specific value. The engine will examine multiple iterative designs to provide the best solution based on the imposed constraints. Of course, in some cases, if too many restrictions are imposed on the engine, it may cause the engine to not optimize the desired optimization results.
Overall, the online design tools of the three manufacturers can greatly help power supply design and development, shorten the design cycle, and rely on their rich design experience to provide many popular and reliable power supply design solutions. In particular, PI not only takes into account the design experience of junior engineers, but also provides a complete design solution, but also opens the editing interface of all components for senior power engineers to support customized design. It is hoped that these online design tools can help engineers to carry out effective and fast product selection and evaluation, and truly shorten the product design cycle.