Everything You Need to Know About Flyback Transformer

A flyback converter is a simple switch-mode power supply for AC or DC applications. This low to the mid-power device that supports multiple outputs is designed to transfer power from the input to the output during off-time. It's found in a television set, plasma lamp, and many other electronic devices that require high voltage.

Here are important facts for you to know about this convenient device, which allows for output to be at a higher or lower level than the input.

Key Components of Flyback Transformer

• Primary switch
• Mutually coupled inductor
• Output rectifier
• Input capacitor
• Output capacitor

How a Flyback Converter Works

The primary switch is usually a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), a three-terminal transistor. It's used for switching or amplifying electronic signals within an electronic device.

When the switch is on, power is stored in the transformer, as the output diode is turned off. Energy remains in storage until the switch is turned off. The diode allows current to flow in just one direction. Current from the transformer increases proportionally to the input voltage, as output voltage enters the diode.

Once the MOSFET is switched off, the transformer current flows through the diode, which decreases in proportion to output voltage.

A flyback transformer, also known as a line output transformer, comprises coupled inductors, making it unique from a typical transformer. It generates voltage from a few kilovolts up to 50 kilovolts with high-frequency currents from 17 kHz to 50 kHz.

It's capable of transferring or storing energy with the help of a coil winding on a ferrite core containing an air gap. The primary and secondary windings are used as separate inductors.

Flyback Converter Advantages

One of the main advantages of a flyback converter is that it's a low-cost alternative for stepping power up or down. Another key advantage of a flyback converter is that it's very basic with a limited number of components compared with other switch-mode power supply units.

It's also useful when you want to isolate multiple output voltages from the primary. Finally, it provides the convenience of a single control for regulating multiple output voltages.