This tutorial by Sam Ben-Yaakov explains the design and operation of a flyback converter power stage, focusing on a practical example based on a reference design from Premier Magnetics. The circuit uses a TOPSwitch controller by Power Integrations, which integrates a power transistor and control circuitry into a single unit, simplifying the design. Key features include an optocoupler for isolated feedback, a TL431 adjustable shunt regulator for precise voltage reference, and safety capacitors to handle high-voltage isolation. Operating in Discontinuous Conduction Mode (DCM), the converter offers simplified loop stability and feedback control. The tutorial also covers calculations for voltage ripple, inductance, and voltage stress on components, highlighting the importance of proper clamping and safety measures.
Additionally, the tutorial identifies and corrects a schematic error found in a LinkedIn post, where the common mode filter was incorrectly connected, posing a severe safety risk. It explains the role of common mode chokes in attenuating differential and common-mode noise and demonstrates testing procedures using a Line Impedance Stabilization Network (LISN). The presenter emphasizes the need for proper design, component selection, and adherence to safety standards while noting that the specific TOPSwitch discussed is obsolete, with modern alternatives offering advanced features like programmable current protection. This overview serves as both an educational guide and a cautionary note for circuit designers.
Video content
- Flyback converter background
- FC reference design
- Floating power supply
- Regulated and non-regulated output
- Maximum drain voltage
- Input filter – common mode choke
Resource: Passive Components Blog
