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Fly-Buck™ isolated DC/DC converters

Create an isolated supply by replacing your buck inductor with a transformer

Isolated DC/DC Fly-Buck™ converters simplify the task of generating isolated positive and negative supplies using only a small number of off-the-shelf external components. Unlike traditional flyback converters, this flexible topology does not need an opto-coupler, resulting in a smaller and more cost-optimized isolated solution.

Flyback-like isolation

Generate positive and/or negative isolated outputs

Multi-output

Add coupled windings to generate multiple isolated outputs

Simple design

A familiar synchronous buck converter base-architecture with common off-the-shelf components

Small solution size

High integration and very few external components

What is a Fly-Buck™ converter?

The Fly-Buck converter topology takes a common synchronous buck converter and adds coupled windings to the primary inductor to be transformed into a cost-effective solution for multiple, flyback-like isolated outputs (Vpri and Vsec in the diagram below). The transformer turns ratio determines the secondary output voltage, which closely tracks the primary output voltage and thus eliminates the need for an optocoupler or auxiliary winding. 

flybuck-topology

Featured products

LM5161

Wide input 4.5-V to 100-V, 1-A synchronous buck / Fly-Buck converter

LM5160

LM5160 wide input 65V, 2A synchronous buck / Fly-Buck converter

LM5017

7.5-100V wide vin, 600mA constant on-time synchronous buck regulator

LM5018

7.5-100V wide Vin, 300mA constant on-time synchronous buck regulator

Featured design resources

Reference design for generating multiple isolated bias supplies from a nominal 24V input using a single LM5017 and a low-profile transformer.

See how easy it is to pair your Fly-Buck with an off-the-shelf coupled inductor from Coilcraft

See our E2E™ technical support forums for your source to fast, verified answers and design help from our experts.

Read about a wide variety of Fly-Buck (TM) topics in our blogs.