Inductive-Boost DC-DC Converters

Sept. 15, 2005

What is an inductive-boost dc-dc converter?

Closing the switch causes current to build up through the inductor, as shown in the simplified inductive-boost dc-dc converter circuit (Fig. 1). Opening the switch forces current through the diode to the output capacitor. Multiple switching cycles build the output capacitor voltage due to charge it stores from the inductor current. This results in an output voltage that’s higher than the input.

What determines the output voltage of the inductive-boost dc-dc converter?

In the real circuit of Figure 2, an IC with an integrated power MOSFET replaces the mechanical switch, and pulse-width modulation (PWM) control turns the MOSFET on and off. PWM duty cycle always determines the output voltage, which is twice the input for a 50% duty cycle. Stepping up the voltage by a factor of two causes the input current to be twice the output current. In a real circuit with losses, the input current is slightly higher.

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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.