Non-Isolated DC-DC Converters

Oct. 27, 2005

What's the difference between isolated and non-isolated dc-dc converters?

Isolation describes the electrical separation between the input and output of a dc-dc converter. An isolated dc-dc converter uses a transformer to eliminate the dc path between its input and output. In contrast, a non-isolated dc-dc converter has a dc path between its input and output. Non-isolated dc-dc converter designs usually employ ICs specifically intended for that purpose.

Why is isolation necessary for system power sources?

For safety considerations, there must be isolation between an electronic system's ac input and dc output. Isolation requirements cover all systems operating from the ac power line, which can include an isolated front-end ac-dc power supply followed by an isolated "brick" dc-dc converter, followed by a non-isolated point-of-load converter. Typical isolation voltages for ac-dc and dc-dc power supplies run from 1500 to 4000 V, depending on the application.

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About the Author

Sam Davis 2

Sam Davis was the editor-in-chief of Power Electronics Technology magazine and website that is now part of Electronic Design. He has 18 years experience in electronic engineering design and management, six years in public relations and 25 years as a trade press editor. He holds a BSEE from Case-Western Reserve University, and did graduate work at the same school and UCLA. Sam was the editor for PCIM, the predecessor to Power Electronics Technology, from 1984 to 2004. His engineering experience includes circuit and system design for Litton Systems, Bunker-Ramo, Rocketdyne, and Clevite Corporation. Design tasks included analog circuits, display systems, power supplies, underwater ordnance systems, and test systems. He also served as a program manager for a Litton Systems Navy program.

Sam is the author of Computer Data Displays, a book published by Prentice-Hall in the U.S. and Japan in 1969. He also authored the book Managing Electric Vehicle Power. He is also a recipient of the Jesse Neal Award for trade press editorial excellence, and has one patent for naval ship construction that simplifies electronic system integration.

You can also check out additional articles on his other author page.