Multi-Output Fly-Buck Regulator Offers Wide VIN, Isolation And Low EMI

Focus:

The power management requirements in industrial, medical, automotive and transportation end markets are setting new challenges for design engineers. System performance requirements for the power converters dictate high density and high switching frequency coupled with increasing emphasis on a wide input voltage range, multiple output rails, galvanic isolation, and compliance with EMI regulations and, in many cases, stringent transient and safety standards. The Fly-Buck converter has gained prominence in providing low-current auxiliary and bias outputs from a widely-ranging input up to 100 V, especially if both isolated and non-isolated rails are required. In comparison with conventional flyback or push-pull topologies, the Fly- Buck offers simplicity, versatility, small size, high reliability, and low BOM cost. This article discusses the advantages of the Fly-Buck. First, a short explanation of Fly-Buck operation is given. Then a multi-output, EMC-compliant Fly-Buck design example based on the LM5161 controller is described including details on its input filtering and circuit protection, transformer design, switching characteristics and PCB implementation.

What you’ll learn:

• How to understand the benefits of the Fly-Buck topology in multi-output power supply applications
• How to design a multi-output Fly-Buck converter

Notes:

A related circuit configuration, the Fly-Buck-boost, is also shown in this article.

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Author & Publication:

Timothy Hegarty, Texas Instruments, Phoenix, Ariz., How2Power Today, Sep 15 2016

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