Terminology » RF Components » Fly-back Converter: Advantages and Disadvantages

Fly-back Converter: Advantages and Disadvantages

fly-back converter dc-dc converter power supply disadvantage advantage

This page covers the advantages and disadvantages of the Fly-back DC-DC converter, including its circuit and working operation. We will explore the benefits and drawbacks of this converter type.

What is a Fly-back DC-DC Converter?

A DC-DC converter is an electronic circuit that modifies one voltage level to another. It’s essentially a voltage regulator comprised of switches, an inductor, and a capacitor for power conversion.

DC-DC converters are used in a variety of applications and can be categorized based on isolation between the input and output circuits:

  • Isolated DC-DC Converter
  • Non-isolated DC-DC Converter

Isolated DC-DC converters can be further divided into the following sub-types:

  • Fly-back
  • Forward
  • Half bridge
  • Full bridge
  • Push Pull

Fly-back converter circuit

Fly-back Converter Circuit and Working Operation

The flyback converter circuit is shown in the figure above. The flyback is essentially a buck-boost chopper with isolated sections achieved by using a transformer. The voltage ratio is multiplied with the additional advantage of isolation.

It’s utilized in both AC-to-DC and DC-to-DC conversions, providing galvanic isolation between the input and output. It can present single or multiple isolated output voltages and operates across a wide range of input voltage deviations.

Compared to other switched-mode power supply circuits, fly-back power supplies generally have lower efficiency. However, the technique is simple and relatively inexpensive, making it suitable for low output power ranges.

Typically, Fly-back converters offer efficiency in the range of 75% to 80%, with power ratings from 1 Watt to 50 Watts.

Benefits or Advantages of Fly-back Converter

Here are the benefits of using a Fly-back converter:

  • The primary advantage is that the output filter inductors, which are essential for all forward topologies, are not necessary for the fly-back. This is because the transformer in the fly-back acts as an inductor, not purely as a transformer.
  • In many cases, an LC filter is added to the load side of the fly-back regulator to reduce output voltage ripple.
  • The voltage rating on secondary components is low.

Drawbacks or Disadvantages of Fly-back Converter

Here are the drawbacks of using a Fly-back converter:

  • Higher EMI (Electromagnetic Interference) due to the air gap.
  • Higher ripple current.
  • Requires more output and input capacitance.
  • Higher losses.
  • Right-half-plane pole in the compensation loop, which can complicate control design.

Conclusion

To fully grasp the advantages and disadvantages of the Fly-back converter, it’s essential to understand the fundamentals of its operation.