Making an electronic product is both an art and a science. Complex electrical engineering principles guide the designers’ choices and compromises, but putting all the pieces together is also an art that requires thoughtfulness and experience. To help with both of these, ST offers platforms and development tools. One of them is eDesignSuite, an application that helps design and simulate a circuit based on specific components. It allows a user to modify and experiment quickly to come up with the optimal solution. In this post, we will look at two case studies to better understand the power of eDesignSuite.
To use the application, simply create an account on my.st.com. Once logged in, go to https://my.st.com/analogsimulator/. The interface (seen above) will present you with a series of applications, because what makes this tool special is its practical aspect. Instead of simply offering a blank canvas, eDesignSuite starts by asking what the engineer is trying to accomplish to offer relevant data and suggest components. In the first case study, we will design a step-down converter, simulating a circuit that would need to take the voltage of a typical power supply for a mobile device, and convert it to feed a regulated voltage to a component in the circuit, such as an MCU.
Case Study #1: Starting Your Power Supply
To start, simply select “Power Conversion,” ”Power Supply,” and ”DC/DC.” One could also choose between an isolated or non-isolated system, but for the sake of our example, we will simply push the button “Create” next to “DC/DC”. At this stage, we have to enter very basic information about our circuit. Since we are simulating a mobile application, a minimum input of 6 V, a maximum input of 12 V, and an output of 3.6 V/1 A is fairly classical.
The system will use these values to automatically filter the available ICs. People looking to design around a specific product can use the search bar (top right) to immediately access a particular part, but this automatic selection will allow most users to quickly browse ST’s catalogue, and make the best decisions. In our case, we will select the first component in the list, the L5981 buck converter, then click “Start Design.”
Case Study #1: Designing Your Power Supply
At this stage, eDesignSuite generates a schematic showing everything the engineers need to integrate the buck converter, as well as graphs simulating the efficiency of the system, voltage and current variations over time, as well as power losses. The bill of material is a single click away by pressing the “BOM” button at the top right corner. Furthermore, users can start tweaking their design directly from the schematic panel by clicking on the little tools icon found at crucial intersection of the circuit, or by changing the components’ values written in blue.
The left panel details the circuit’s specifications, and allows users to change operating conditions (voltage in, current out, and temperatures), to see how they’d affect the design’s performance. However, at this stage, many may simply want to see how their circuit integrates with the rest of their system. Therefore, eDesignSuite offers a great feature called “Export to PSpice” found in the “Save” Menu. Selecting it will generate a Zip file containing a folder called “Full,” which hosts, among other things, the libraries needed to run the current simulation under PSpice. This export feature is not available for all schematics, but ST continues to increase the number of solutions compatible.
Interactivity is a very important part of eDesignSuite and to understand that aspect of the application, we’ll dive into the second case study.
Case Study #2 : Designing Your NFC antenna
To start designing an NFC Antenna, we simply select “RF Design” from the main menu, then “NFC Antenna Design.” Here, we see another important feature of eDesignSuite : as in the first case study, the interface automatically fills in all of the components’ values, so users don’t have to know all the specific details of each piece of the circuit. It just works together, greatly hastening the designing process.
At this point, it is possible to change the antenna design on the fly to fit a specific circuit. In our example, if we modify the length to 30 mm, we see what the design would look like at the bottom of the screen, and the equivalent inductance is immediately updated to 777,64 nH, so we see right away what kind of impact our choices will have on the performance, and if we are hitting the necessary targets. It’s this kind of interactivity that makes eDesignSuite shine. In this example, an NFC antenna would need to reach between 4.7 µH and 5 µH, so we can easily play with the values to create a shape that matches our product and hits the intended target.
Errors and Mistakes
To guard engineers against a fatal mistake, the system is smart enough to stop certain simulations when one is making a compromising choice. In our second case study, if we leave the length to 30 mm, and accidentally put a width of 3 mm, the system throws an error to explain that such a design is impossible.
Finally, ST has put in place a community of designers and engineers. Clicking on the help button and selecting “Communities” will open a special thread that can be used to ask questions in case one gets stuck on a design, or need help with the software.