12.1.1 Buck-Regulator Layout Guidelines
Layout is a critical portion of good power supply design. The following guidelines will help users design a PCB with the best power conversion performance, thermal performance, and minimized generation of unwanted EMI:
- Put the feedback network resistors near the FB pin and away from the inductor to minimize coupling noise into the feedback pin.
- Put the input bypass capacitor near the VIN pin to decrease copper trace resistance which effects input voltage ripple of the device.
- Put the inductor near the SW pin to decrease magnetic and electrostatic noise.
- Put the output capacitor near the junction of the inductor and the diode. The inductor, diode, and COUT trace should be as short as possible to decrease conducted and radiated noise and increase overall efficiency.
- Make the ground connection for the diode, CVIN, and COUT as small as possible and tie it to the system ground plane in only one spot (preferably at the COUT ground point) to minimize conducted noise in the system ground plane.
For more detail on switching power supply layout considerations refer to the AN-1149 Layout Guidelines for Switching Power Supplies application report.