Technical Information Site of Power Supply Design

2015.12.10 AC/DC

Overview of Design Method of PWM AC/DC Flyback Converters

Design Method of PWM AC/DC Flyback Converters

In this serial, with the topic “Design Method of PWM Type AC/DC Flyback Converters,” we describe a design procedure and method using AC/DC converter ICs.

Demand for power savings in electronic devices has become increasingly challenging, requiring both high efficiency and a low power consumption at standby. For AC/DC converters, there is a crying need for on-board design and further optimization.

Because designing an AC/DC converter involves dealing with high voltages and requires transformer design, designers tend to shy away from the task. The task, however, may be worth the challenge if it leads to the fabrication of optimal AC/DC converters capable of meeting the demand for a high degree of power savings. As an added incentive, increasing numbers of control ICs have come into play that permit the construction of AC/DC converters in relatively simple manner.

Given these conditions, starting with an overview of a procedure for designing an AC/DC converter, we will describe how to verify the specifications for the power supply unit to be designed, how to select the specific IC to be used, and discuss actual design examples.

Each explanation that we provide consists of several subsections. Also, since the design process follows a certain procedure, we will describe the process in logical sequence. For an overall understanding of what follows, we recommend that you read the material that following in the sequence in which it is presented. Although some subsections stand by themselves, you may find it easy to follow the design examples by viewing them in the sequence in which they are given. As a helpful tip, the list below provides an overall structure of the material presented in this section.

＜Design Method of PWM AC/DC Flyback Converters＞

• 1. Isolated Flyback Converter Basics
• Switching AC/DC Conversion
• Fyback converter: Characteristics
• Fyback converter: Operation and Snubber
• Discontinuous & Continuous Modes
• 2. Design Procedure
• 3. Determining Power Supply Specifications
• 4. Choosing an IC for Design
• 5. Designing Isolated Flyback Converter Circuits
• Transformer Design (Calculating numerical values)
• Transformer Design (Structural design) - 1
• Transformer Design (Structural design) - 2
• Selecting Critical Components – MOSFET related - 1
• Selecting Critical Components – MOSFET related - 2
• Selecting Critical Components – CIN and Snubber
• Selecting Critical Components – Output Rectifier and Cout
• Selecting Critical Components – IC VCC related
• Selecting Critical Components – Setting up an IC, and Miscellaneous
• Addressing EM and Output Noise
• 6. Example Board Layout
• 7. Summary