Technical Information Site of Power Supply Design

2020.09.23 DC/DC

The Importance of PCB Layout Design

PCB Layout of a Step-Up DC/DC Converter

PCB Layout for a Switching Power Supply is as Important as Circuit Design

In designing a switching power supply, the PCB layout design is, like the circuit design, very important. If the PCB layout is not appropriate, not only is the inherent performance of the power supply IC impeded, but operation may be abnormal. In not a few cases, problems arising during prototyping of a switching power supply originate in the PCB layout.

Problems arising from PCB layout include noise (including spikes and oscillations), deterioration of regulation, and unstable operation. In particular, noise is closely related to conformance to recent EMC regulations. In many cases, such problems can be resolved through an appropriate PCB layout.

In this chapter, the following topics will be addressed.

  • ・Current paths in a step-up DC/DC converter
  • ・PCB layout procedure
  • ・Placement of input capacitors
  • ・Placement of output capacitors and freewheel diodes
  • ・Placement of inductors
  • ・Placement of thermal vias
  • ・Wiring for feedback path
  • ・Ground
  • ・Case of synchronous rectification

*Changes may be made.

This chapter discusses PCB layouts for step-up DC/DC converters. For information on PCB layouts for step-down DC/DC converters, please refer to DC/DC Converter PCB Layout in Tech Web Basic Knowledge, DC/DC Design Edition.

Examples of the circuit diagram and PCB layout diagram of a BU33UV7NUX-EVK-101 evaluation board for the BU33UV7NUX synchronous rectifying step-up DC/DC converter, as well as an actual board.
*The PCB layout diagram does not include the jumper patterns, terminals, or other features included in evaluation boards.

Key Points:

・When designing a switching power supply, similarly to the circuit design, the PCB layout design is also important.

・In this chapter, the PCB layout of step-up DC/DC converters is explained.

PCB Layout and Selection of Peripheral Parts

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