Three steps to design a switching power supply

 Nowadays, the design of switching power supply is relatively mature, but how to make the design of switching power supply simpler still requires a certain amount of effort. Now, senior netizens have summarized the following three steps based on their own practical experience to teach you how to easily handle the design of switching power supply .

　　The first step in online power supply design is to define the power supply requirements, including voltage range, output voltage, and load current. Possible solutions are automatically evaluated and one or two recommended solutions are presented to the user. This is also the first place where designers can run into trouble: if the requirements are not expressed correctly (for example, if the actual input voltage range is higher or lower than the input value), unsuitable solutions will also be displayed. Users can try multiple sets of requirements, but they must have a clear concept of the system requirements.

　　Once a regulator solution has been selected, the components for the circuit can be determined. The tool displays the component numbers. The user can change to a preset replacement or enter a custom part. There are guidelines for component values ​​and all critical parasitic values. If custom components are used that differ greatly from the recommended values, performance may be degraded.
　　1 Electrical and Thermal Simulation
　　Electrical simulation supports some solutions. These simulators display the logic diagram, and the user can further change components and run tests on the regulator circuit. Available tests include Bode plots, steady state, line transients, load transients, and start-up. (Note that Bode plots are only available for circuits that use fixed-frequency regulator ICs.) To make online testing more useful, the user should carefully check all test conditions. Input voltage and load current may change for each test, and the default values ​​may not match the user's system. The user must first estimate what the results should be, and if the simulation results are different, find out why.

　　Thermal simulation can be used for many scenarios. The online tool evaluates the voltage regulation circuit implemented on a PCB using a reference design layout. Results for component and board temperatures are displayed in full-color graphics and tables. Since thermal simulations run quickly (results are available in minutes), they are not as accurate as a detailed CFD (computational fluid dynamics) simulation that can take hours. However, temperature estimates are generally within 20°C of the actual value. This is sufficient to identify hot spots on the board or components to prevent overheating.

　　2 Testing the Prototype
　　The final step before moving a switching regulator design into production is to build a prototype for bench testing. Some solutions include support for custom designs, while others come with reference design boards. The power of online tools may tempt you to skip this step – don’t! Most designs work well, but some require careful layout to get the best performance. Actual components may not exactly match simulation results, especially when their parasitics are taken into account, and actual performance (including board layout effects) may differ slightly from simulation results.
　3 Performance Evaluation
　　Once the circuit components have been selected, it is time to evaluate performance. Generally, performance is evaluated by looking at frequency response values ​​(crossover frequency and phase margin), peak current and voltage, and thermal performance values ​​(efficiency, junction temperature, and component temperature). Although these calculations are based on models, the simulation results match the bench data very well.