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Posted on 07 August 2019

Create Embedded Power Designs Online

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Online development environments are becoming increasingly sophisticated. This article describes the operation and use of a new tool, Embedded Systems Power Designer, that enables web-based design of the power supply for Embedded microcontrollers and FPGAs. The application uses the processing power of cloud-based servers and an intuitive user interface based on the latest HTML 5 capabilities to implement an interactive environment for design directly in the web browser.

By Devin Crawford, senior application engineer, Transim Technology Corporation

The tool contains a vast amount of information about individual components and their application. With the aid of integrated intelligence, engineers can access this extensive knowledge and use it to design an application-specific power supply in a matter of minutes. The corresponding circuit diagram together with a parts list and summary of the design can either be stored in the "cloud" or downloaded to the local computer.

Background

In the last ten years, the Internet has become the most important resource in the day-to-day processing of technical tasks. Everyone can quickly find background information on a wide range of topics on the Internet, or get access to important standards and regulations. When working on new design tasks, an information resource such as datasheets.com is practically indispensable for many development engineers when it comes to searching for modules or integrated circuits.

Despite the huge array of information that is available, one major challenge remains: retaining an overview and using this large volume of information effectively. Arrow Electronics has used its position as one of the leading providers of electronic components to develop a unique solution to this problem. The solution allows users to access comprehensive sources of information via online design tools. These applications use modern cloud-based technologies to present information from hundreds of data sheets and technical help documents in an interactive environment. Engineers can quickly navigate through complex design challenges while ensuring sufficient flexibility for the application. The current version of the Embedded Systems Power Designer illustrates this solution.

Scalable online support

Due to their high level of flexibility and relatively low cost, programmable logic modules such as FPGAs are an attractive solution for applications in automation and control technology. However, the successful use of such modules is subject to stringent requirements regarding the power supply. The power requirement depends on the module programming, and individual supply voltages must meet exacting specifications relating to the AC component. Development engineers are therefore faced with tasks that are, to some extent, well outside their core competencies. The online design environment simplifies the overall design process by dividing tasks into separate steps. The specifications of the FPGA manufacturer, which otherwise can only be ascertained from data sheets that are several pages long, are integrated automatically at every step.

Access to this development environment is available via the Arrow Electronic Components website. First-time users receive their access data following registration. This means that information from completed development steps can be stored at any time on the server for subsequent use. Multiple users can even exchange circuit diagrams and other content with each other directly within this environment. It is therefore also a valuable tool for application engineers in providing support for their customers.

Circuit diagram editor for designing the circuit diagram

When the user opens the program, the Embedded Systems Power Designer displays a blank circuit diagram editor as shown in Figure 1. The circuit diagram editor allows the user to visualize the supply plan for the FPGA with high-level abstraction. Individual converters are synthesized, simulated, and can even be modified by the user at component level in a deeper hierarchical level. The requirements of the central module (e.g. the Altera Stratix IV FPGA) are passed down through the hierarchy so that design objectives for the individual converters meet the system requirements.

The design process is started by selecting an FPGA and placing it in the circuit diagram editor as a module. Several FPGAs from Altera can currently be selected. FPGAs from other manufacturers as well as microcontrollers will be available in the near future. Voltage specifications and tolerances for the individual power supply networks are automatically implemented as properties of the FPGA module. The power requirement for individual networks can either be entered manually, or, in the case of Altera FPGAs, values can be read in from the Altera "Early Power Estimator" (EPE) as shown in Figure 2.

Current and voltage specifications for the FPGA. The power requirement can be loaded manually or from the Altera "Early Power Estimator"

The EPE provides estimated upper limits for the power requirement based on the programming of the FPGAs selected by the user. This ensures that the resulting converters are optimized for the relevant application. This link to the Altera design environment saves time and minimizes the probability of errors occurring early on in the design phase. After the FPGA has been placed in the circuit diagram and the supply specifications have been defined, a concept for the power supply is automatically created in the circuit diagram editor. An example of the power supply plan for the Stratix IV E FPGA is shown in Figure 3. In this screen, individual converters are defined as placeholders, which, thanks to forwarding the requirements for current, voltage and their tolerances, act as templates for designing the individual converters.

The topology of the FPGA circuit diagram is created automatically with placeholders for individual converters

Design of the individual converters is started by opening the corresponding module in the power supply plan. Double-clicking on one of the modules opens a configuration screen, as shown in Figure 4.

Input screen for designing a converter

The connections at the higher hierarchy level in the circuit diagram between converter and FPGA act as the interface for transmitting supply requirements from the FPGA to this design screen.

This information is then used to prioritize the available controller ICs in the selection list. This means that from a list containing several hundred ICs, those which best suit the specific electrical specifications for the design are displayed with highest priority. To do this, the filter algorithm accesses a wide range of data sheets and application notes and saves the engineer, who does not have detailed knowledge of the converter design, many hours if not days of work. In addition to the numerous ICs listed, there is also an item called "Design It". This is linked to an interactive design tool which creates the entire circuit around the converter ICs. The circuit is presented schematically, and in many cases there is the option to check the transient and stationary behaviour of the circuit using a simulation. In this step, it is also possible to modify component values, and the effects of any change are checked in real-time with the simulation. There is no increased computing effort associated with the simulation, as resource-intensive processes are run on the server. Figure 5 shows the circuit diagram for a converter and the results of the simulation.

View of the circuit diagram and results of the simulation for a converter circuit. A circuit diagram and parts list simplify the step into production

The results are displayed in a window together with numerous functions such as marker, zoom on/off, and display options for individual curves. The variety of functions and fast response time expected of desktop applications are available together here in the same online environment.

The parts list for the circuit can be displayed in the next step. The design is finished off by defining price information using a parts list specified by the user. The availability and price are displayed and the parts list can be downloaded as a table. If individual components are to be replaced or swapped out according to defined criteria, there is a useful filter function that can be used. Figure 6 shows how a capacitor can be selected according to c-value, housing, manufacturer or maximum operating voltage.

A selection filter provides help in selecting individual components from the parts list according to additional criteria

The steps described here integrate specifications and application expertise from a variety of modules in order to implement an optimized topology for the power supply of a FPGA. The algorithms support a fast online design process that can be adapted to the specifications of each individual design. Following completion of the individual converter circuits, a check is always carried out to make sure that the specifications for the power supply have been met from the point of view of the FPGA. This check can then be carried out manually by selecting "Check Design" at the top of the circuit diagram. A summary of the complete supply, including all converters, simulation results and parts lists is then provided on the "Summary" page. The parts list can also be downloaded or adjusted at this stage, as shown in Figure 6.

Summary

The "Embedded Systems Power Designer" online application can be used to implement complex power supplies for embedded modules. This application combines a wealth of application expertise in an intuitive user interface that guides engineers through the complexity of the task in just a few simple steps. Based on the specifications of the FPGA, circuits are adapted for converters and their components. At the end of the process, engineers get all the design information such as the circuit diagram, parts list, topology of the supply, and simulation results as a download.

 

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