With the improvement of product integration, the total power consumption of various types of chips on the PCB has increased, and the power supply design of the product has become more and more challenging. How to quickly display the complex power connection relationship of a product clearly with graphics Come out (hereinafter referred to as "power tree", "PowerTree"), and then enter the value on the power tree and share it with related software calls will be a topic of great interest to people such as product hardware, PCB, PI simulation. This article takes a power supply of a data accelerator card product as an example, introduces the process of using the Sigrity PowerTree software module to extract the structure of the power supply "power tree" in the PCB, and assign the corresponding voltage, current and other parameters to the components in the "power tree" Finally, the data was seamlessly imported into the corresponding module of the PowerDC simulation process. Finally, it was found that this method of extracting and applying the power tree is very convenient for module reuse, editing, correctness checking and improving work efficiency.
background
When PCB conducts PI simulation splitting, a necessary step is to sort out the data when different voltages are supplied to different components. It is time-consuming and labor-intensive to sort these components and their corresponding voltages and currents quickly and accurately. And work that requires patience. Under the premise of obtaining a very standardized schematic original document, it will not be difficult to sort out these data based on the power structure and component information of the schematic, but the first-line engineers understand that PCB/PI engineers cannot get the principle in most cases Drawing files, you can only work hard on PCB files or PDF format schematics, and then sort out the connection relationships between power supplies and components and the corresponding voltage and current values ​​from these "generally non-standard" schematics.
In the PI simulation process, it is the goal that engineers have been pursuing to find a new tool to quickly sort out the connection relationship between the power supply and the components, or to let the people who know this aspect provide these data. This will not only make the data more secure and also Can improve work efficiency. This article will describe a tool (PowerTree) with this function to extract the power structure (hereinafter referred to as: power tree) on a high-speed product, and share the methods, ideas and videos.
Power tree extraction method
In daily PI simulation work, different companies will have different methods when sorting out components and current levels at different voltages, mainly involving the following types of work and methods:
Method 1: According to the materials provided by the customer, draw the corresponding power supply structure by hand, as shown in Figure 1 below. This approach requires understanding the PCB or schematic diagrams and then manually outputting them later. Drawing structure diagrams later will be time-consuming and has a certain threshold for the combing personnel’s knowledge and skills.
*Data comes from Chapter 11 of "Signal and Power Integrity Simulation Design and High-speed Product Application Examples".
Figure 1 Hand-drawn schematic diagram of the power supply structure included in the product
Method 2: Use EXCEL form to sort out in detail, calculate the information of each component and power consumption involved, as shown in Figure 2. This process also takes a long time, and the data needs to be confirmed with the customer, which is the most commonly used method.
*Data comes from Chapter 11 of "Signal and Power Integrity Simulation Design and High-speed Product Application Examples".
Figure 2 Manually organize data and use EXCEL display mode
Method 3: Display the "highlight" network on the PCB. This type of display is more intuitive and is used by most current PI engineers to check the network connection.
Figure 3 Display effect of PCB power supply and related components connection
The method provided in this article---Use the PowerTree tool to extract the power tree
Using the PowerTree module provided by Sigrity, the software automatically extracts all the components connected to the network and displays them independently in the newly created diagram, as shown in Figure 4. Compared with the traditional method, it has a "refreshing" feeling.
Figure 4 The overall effect of using PowerTree automatic extraction
The above shows the main IC and the resistors, inductors, magnetic beads and other components used for the intermediate connection. You can also display all the capacitors connected to the power supply. Because a third-party netlist is needed to generate this graph, these tasks can be The schematic designer firstly assigns the model of the capacitive element, the voltage/current of the IC and other data, and saves the assigned file for direct import in the subsequent PI simulation.
Figure 5 POWERTREE shows the capacitor assignment model and the effect after the IC assigns the current value
Example application experience
After adding the use of PowerTree to the example in Chapter 11 of "Signal and Power Integrity Simulation Design and High-speed Product Application Examples", it is found that the "pain points" that PowerTree solves mainly focus on the following aspects:
1. The main power connection structure of a project is separately displayed graphically, which is very intuitive and easy to edit
2. In the early stage of the PI simulation stage, the working current and power supply model of the corresponding component can be completed by the schematic engineer on PowerTree, and later directly transferred in the PI storage, thereby saving time and reducing errors
3. Through PowerTree, it is also convenient to provide references for projects with similar power applications
4. The components in PowerTree can be added or removed as needed and can be distributed to different departments for inspection
Data relationship diagram between PowerTree and other software modules
PowerTree data and surrounding software modules call each other, and the corresponding logical relationship is shown in Figure 6.
Figure 6 Data relationship between POWER and other modules
PowerTree extraction process
Here is how to use PowerTree to transfer into a third-party netlist. According to the daily work experience of PCB DESIGN HOUSE, in many cases the original schematic files are not available, and the first-party netlist is not easy to obtain, so the third-party netlist is most suitable. The current EDA software can basically output the third-party netlist format required by PowerTree, so the use of PowerTree can be applied to more EDA design platforms.
Note: The method here is based on the contents of Chapter 11 in "Signal and Power Integrity Simulation Design and High-speed Product Application Examples", using PowerTree to extract from the PCIE golden finger (power supply at U2) to each component (U36, U41, U44, U51) Power tree structure.
Note: The N-Channel MOSFET (U39) in the link needs to be set to the through type and the corresponding on-resistance (the on-resistance is 0.014Ω by checking DATASHEET).
Figure 7 Connection situation of MOS tube in 12V link
PowerTree is simple to use, the main steps are:.
a) Create a new PowerTree
Use the Allegro layout netlist file third-party netlist option in the New Power Tree interface in Figure 8
Figure 8 New PowerTree interface and recommended options
b) In the following, you only need to operate step by step according to the interface process provided by the software (omitting the intermediate steps here, you can refer to the HELP document that comes with the software, or watch the corresponding use video on the author's WeChat public account: amo_eda365), to Figure 9 The step of saving the edited data (Vrm, Sink, discrete component value or model) on PowerTree as a file ending in pwt and importing it into PowerDC.
Figure 9 PowerTree application menu in the PowerDC simulation test process
c) The effect comparison chart before and after the data in PowerDC is seamlessly imported with the Apply Power Tree button.
Figure 10 The SINK data of each IC to be filled before Apply Power Tree
Figure 11 Sink corresponding data of each IC has been automatically updated after Apply Power Tree
It can be seen that the data set by PowerTree can be directly imported and updated during the PowerDC simulation process, which greatly improves work efficiency and reduces the chance of error.
in conclusion
The PowerTree tool used in this article has a wide range of applicability. The third-party netlist generated by other EDA design platforms can be used, and the relationship between the power tree and the related voltage and current values ​​and assignment models work in the schematic stage. Completed by different people. The article uses the PowerTree function module in the actual project PI simulation verification and found that PowerTree is very good in terms of intuitiveness, ease of use and efficiency improvement of the power supply network.
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