Gate Drivers: Key To Power SwitchingSponsored by: IXYS CORP.

Nov. 15, 2004

Consider all aspects of gate-driver design to ensure power-system reliability and performance.

Power-Switching Enablers Low-power, logic-level switching signals can't drive moderate- to high-power semiconductor switches, such as the MOSFET (metal-oxide semiconductor field-effect transistor) and IGBT (insulated-gate bipolar transistor). To solve this problem, gate-driver ICs provide the necessary buffer between low-power switching signals and discrete MOSFET/IGBT power semiconductor switches. Gate-driver ICs are essentially power amplifiers that accept low-level switching inputs and produce switched outputs of hundreds of milliamperes to tens of amperes to drive MOSFET and IGBT gates. These MOSFET/IGBTs can then handle loads from milliwatts to kilowatts, depending on the gate-drive current and the power-handling capability of the MOSFET/IGBT.Performance Basics To be effective, the gate driver's input stage must be compatible with both TTL and CMOS inputs. It also must be immune to latch-up over its entire operating range. The output stage can supply single-ended, half-bridge, or three-phase bridge drive for MOSFETs/IGBTs. Most gate drivers can handle output loads from 2000 to 3000 pF, which is approximately the input capacitance of a typical power MOSFET or IGBT. Today's gate drivers can exhibit rise and fall times of less than 100 ns with the same order-of-magnitude propagation delays. Because they accept low-voltage inputs and handle higher output voltage levels, gate drivers must have efficient, reliable, and non-latching voltage-level translation circuits. Gate drivers feature shutdown options as well as overcurrent, undervoltage, and overtemperature protection.

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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.