In any switching power supply design, the physical design of the PCB (Printed Circuit Board) is the final step. If the design approach is incorrect, the PCB may radiate excessive electromagnetic interference, leading to unstable power supply operation. The following are points to consider for each step of the design process:

1. From Schematic to PCB Design Process:

   • Establish component parameters.
   • Input the schematic netlist.
   • Set design parameters.
   • Manually place components.
   • Manually route traces.
   • Verify the design.
   • Review and double-check.
   • Output CAM data.

2. Parameter Settings:

   • Ensure that the spacing between adjacent traces meets electrical safety requirements while also allowing for ease of operation and production.
   • Keep the minimum spacing sufficient to withstand the voltage.
   • Increase the spacing for signal lines with significant high and low-level differences.
   • Set the trace spacing to around 8mil.

3. Pad-to-Board Edge Distance:

   • The distance from the edge of the pad to the board should be greater than 1mm to avoid damage during processing.
   • Design connections between pads and traces as water droplet shapes to prevent peeling and disconnection.

4. Component Layout:

   • Poor PCB design, even with a correct circuit schematic, can negatively impact electronic device reliability.
   • Avoid placing two fine parallel lines on the PCB close together, as this can create signal delay and reflection noise.
   • Carefully consider ground placement to prevent interference and performance degradation.

5. Filter Capacitor and Grounding:

   • Design the input and output filter capacitor connections to minimize AC energy radiating to the environment.
   • Pay attention to the grounding scheme to avoid undesired coupling and self-excited interference.

6. High-Frequency Signal Handling:

   • For circuits with high-frequency signals, keep traces as short and wide as possible to minimize impedance and inductance effects.
   • Minimize trace lengths to reduce radiation of electromagnetic waves.

7. Input and Output Grounds:

   • The low voltage DC-DC circuit of the switching power supply requires a common reference ground for both sides.
   • Ensure a common ground connection between the input and output circuits for proper voltage feedback.

8. Check and Recheck:

   • Thoroughly check if the design complies with the set rules and production requirements.
   • Verify the proper distances between traces, components, and pads to meet production standards.

9. Output Design:

   • Output gerber files with specific layers for routing, silk-screen, solder mask, and drilling.
   • Pay attention to the outline, text, and lines when setting silk-screen layers.

The above considerations are important for creating a reliable and stable switching power supply PCB design. Careful attention to layout, trace routing, filtering, grounding, and testing will help ensure optimal performance and electromagnetic compatibility.