LM5161-Q1: Design tool for LM5161-Q1 use as Flyback

Marc Liu

Expert 3210 points

Part Number: LM5161-Q1

Hi Team,

Customer want to use LM5161-Q1 as Flyback, but the Webench tool only has Flybuck choice.

So customer wonder if we have Excel tool/ App note or other document to help them calculate the components?

Thank you!

Marc

over 2 years ago

0 Harrison Overturf over 2 years ago

TI__Genius 10685 points

Hi Marc,

The Flyback and Fly-Buck topologies both provide isolation and the ability to generate multiple output rails from a single converter. Since we have more resources available for converting the LM5161-Q1 into the Fly-Buck topology this may be the easier route to choose.

The flyback topology is essentially derived from replacing the inductor of a buck-boost with a transformer while the Fly-Buck replaces the inductor of a buck with a transformer or coupled inductor. To convert the LM5161-Q1 to a flyback style, you'll configure the LM5161-Q1 as an inverting buck-boost then replace the inductor with a transformer.

This article does a nice job of explaining the distinction (it is still referred to as a Fly-Buck in this article):

https://e2e.ti.com/blogs_/b/powerhouse/posts/should-you-use-buck-or-inverting-topology-for-fly-buck?keyMatch=INVERTING%20FLYBUCK%20BOOST

This app note details how to configure a buck converter to an inverting buck-boost:

https://www.ti.com/lit/an/snva856a/snva856a.pdf

This app note details the Fly-Buck equations:

AN-2292 Designing an Isolated Buck (Fly-Buck) Converter (Rev. C) (ti.com)

Hopefully this helps.

Regards,

Harrison Overturf