How to design a switching power supply and which IC to use?
Designing a switching power supply involves several steps and considerations.
Here's a general outline of the process along with some recommendations for choosing an integrated circuit (IC) for a 50W power supply design.
Determine the specifications:
▲ Input voltage range: The range of voltages the power supply should be able to handle. ▲ Output voltage: The desired voltage for the load. ▲ Output current: The maximum current the power supply needs to deliver to the load. ▲ Efficiency: The desired efficiency of the power supply. ▲ Other requirements: Any additional requirements or constraints, such as size, cost, or specific features.
Select the topology: There are different switching power supply topologies to choose from, such as flyback, forward, or buck-boost. The choice depends on your specific requirements and constraints. For a 50W power supply, the flyback or forward topology is commonly used.
Determine the switching frequency: The switching frequency affects the size of the components and the overall performance of the power supply. Select a suitable switching frequency based on your requirements and the trade-offs between efficiency, size, and cost.
Choose the power switch and diode: Select appropriate power switches (MOSFET or IGBT) and diodes that can handle the required voltage and current levels.
Design the transformer: For flyback or forward topologies, a transformer is needed. Design or select a suitable transformer that meets the voltage, current, and size requirements. Consider using a custom transformer design or off-the-shelf transformers.
Design the control circuitry: Choose a controller IC that provides the necessary features for your power supply design. Some popular IC manufacturers for switching power supply controllers include Texas Instruments, Analog Devices, ON Semiconductor, and STMicroelectronics. Look for ICs that offer features such as overcurrent protection, overvoltage protection, and feedback control.
Calculate component values: Design the feedback network, output filter, and other necessary components based on the selected IC and your design requirements. Refer to the datasheet and application notes of the chosen IC for guidelines on component selection and design calculations.
Simulate and verify the design: Use simulation tools like LTspice or PSpice to simulate the circuit and validate its performance. Adjust component values if necessary.
Build and test the prototype: Construct the power supply circuit based on the design. Measure the output voltage, ripple, and efficiency. Make any required adjustments or optimizations.
Ensure safety and compliance: Consider safety measures, such as overcurrent protection, overvoltage protection, and thermal protection. Ensure your power supply design meets relevant safety standards and regulations.
It's important to note that designing a switching power supply requires a good understanding of power electronics and circuit design principles. If you are not familiar with these concepts, it may be helpful to consult with an experienced engineer or refer to application notes and design resources provided by IC manufacturers. Please keep in mind that specific IC recommendations may change over time as new products are released. Therefore, it's recommended to consult the latest resources and datasheets from IC manufacturers to find the most suitable controller IC for your design.
