DC-DC|Design
Overview of Selection of Inductors and Capacitors for DC-DC Converters
2017.02.09
Points of this article
・When designing a DC-DC converter, selection of inductors and input and output capacitors is particularly important.
・It is important to understand the circuit operation and current paths, and the roles played by the various components.
This section begins a new “Design Edition” relating to DC-DC converters. In this chapter, rather than discussing the entirety of DC-DC converter design, we focus on “Selection of Inductors and Capacitors for DC-DC Converters”, and in particular explain the methods for choosing the inductors and capacitors that are principal components of step-down DC-DC converters, and the selection of which has a major impact on performance and characteristics.
First, we review the basic operation of a step-down DC-DC converter and the accompanying flow of current. In order to select inductors and input and output capacitors, it is important to understand the flow of currents in the circuit and the current waveforms.
We present the procedure and calculation equations for selecting an inductor, and describe a selection example. We’ll begin by explaining the relation between an inductor and the inductor current.
With respect to output capacitors, we explain calculation methods and output ripple.
For input capacitors, we likewise describe calculation methods and describe the DC characteristics that must be considered when selecting a device.
Where overall design is concerned, details are provided in the data sheets and application nodes for power supply ICs. Here we will address some issues and practical knowledge that go somewhat beyond such standard materials.
【Download Documents】Switching Regulator Basics
The basics of step-down switching regulators, including their operation and functions, are explained. Comparison with linear regulators, synchronous rectification and diode rectification, control method, auxiliary functions, etc. are also explained.
List of articles related to the「Overview of Selection of Inductors and Capacitors for DC-DC Converters」
Download Technical Documents
Switching Regulator Basics
The basics of step-down switching regulators, including their operation and functions, are explained. Comparison with linear regulators, synchronous rectification and diode rectification, control method, auxiliary functions, etc. are also explained.
DC-DC
- Basic
-
Design
- Overview of Selection of Inductors and Capacitors for DC-DC Converters
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Overview of DC-DC Converter PCB Layout
- Ringing at switching nodes
- Placement of input capacitors and output diodes
- Placement of Thermal Vias
- Placement of Inductors
- Placement of Output Capacitors
- Feedback Path Wiring
- Ground
- Resistance and Inductance of Copper Foil
- Noise countermeasures: corner wiring, conducted noise, radiated noise
- Noise countermeasures: snubber, bootstrap resistor, gate resistor
- Summary
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PCB Layout of a Step-Up DC-DC Converter – Introduction
- The Importance of PCB Layout Design
- Current Paths in Step-up DC-DC Converters
- PCB Layout Procedure
- Placement of Input Capacitors
- Placement of Output Capacitors and Freewheel Diodes
- Inductor Placement
- Placement of Thermal Vias
- Feedback Path Wiring
- Ground
- Layout for Synchronous Rectification Designs
- Resistance and Inductance of Copper Foil
- Relationship Between Corner Wiring and Noise
- Summary
- Evaluation
- Application
- Product Information
- FAQ