Project Analog - April 2008 - (Page 19) Trends in MOSFET gate drivers Contents Viewpoint Calculating Power Dissipation Accelerating Amplifier Design Driving Power MOSFETs Analog news The devices can improve efficiency, reduce size, increase reliability, and simplify the design of switching power supplies By Van Niemela Fairchild Semiconductor / San Jose, CA www.fairchildsemi.com T he long-term trend toward higher density and higher efficiency in switching power supplies is creating strong demand for integrated-circuit MOSFET drivers. A MOSFET (or IGBT) driver is essentially just a specialized power amplifier connected between the output of a power-supply controller and the power switch(es) it must drive. An example application is shown in Fig. 1, where one driver is used for the primary-side power switch and another for a synchronous rectifier. Both are driven from the same “PWM” output of a controller, using a pulse transformer to pass that signal across the isolation boundary, 19 · prOjECT ANAlOg · Apr 08 and using the inverting input of the second driver to obtain the correct phasing. Placing a driver close to the driven switch improves efficiency by increasing switching speed, and it reduces EMI by keeping the loop area of the ac drive current small, minimizing high-frequency “ringing” and radiated noise. Additionally, moving this significant source of power dissipation and electrical noise away from the control IC helps to ensure its proper functioning. “Standard low-side” drivers as shown in Fig. 1 are typically rated for a maximum of 15 to 25 V, and they drive switches (or transformer windings) referenced to the ground level of the input signal. Another com- Microchip analog page MOSFET driver overview Sample center microchipDIRECT Reference designs/ app notes Technical training http://www.fairchildsemi.com http://www.microchip.com http://www.microchip.com/analog http://www.microchip.com/analog http://www.microchip.com/mosfetdriver http://www.microchip.com/mosfetdriver http://sample.microchip.com/Default.aspx?testCookies=true http://www.microchipdirect.com/catalogselection.aspx?returnURL=default.aspx http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1469&filter1=function&redirects=appnotes http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1469&filter1=function&redirects=appnotes http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1423
Table of Contents Feed for the Digital Edition of Project Analog - April 2008 Project Analog - April 2008 Contents Viewpoint About Project Analog Sponsor Calculating Power Dissipation in a MOSFET Driver Accelerating Design of >50-W Class D Amplifiers Driving Power MOSFETs in Switch Mode Power Supplies Synergistic MOSFET Solutions Trends in MOSFET Gate Drivers Analog News—Analog news from multiple sources Enter to win an iPhone Contact Project Analog Sponsor Treelink Microchip Advanced Parts Selector (MAPS) Project Analog - April 2008 Project Analog - April 2008 - Project Analog - April 2008 (Page 1) Project Analog - April 2008 - Contents (Page 2) Project Analog - April 2008 - Viewpoint (Page 3) Project Analog - April 2008 - About Project Analog Sponsor (Page 4) Project Analog - April 2008 - Calculating Power Dissipation in a MOSFET Driver (Page 5) Project Analog - April 2008 - Calculating Power Dissipation in a MOSFET Driver (Page 6) Project Analog - April 2008 - Calculating Power Dissipation in a MOSFET Driver (Page 7) Project Analog - April 2008 - Calculating Power Dissipation in a MOSFET Driver (Page 8) Project Analog - April 2008 - Calculating Power Dissipation in a MOSFET Driver (Page 9) Project Analog - April 2008 - Accelerating Design of >50-W Class D Amplifiers (Page 10) Project Analog - April 2008 - Accelerating Design of >50-W Class D Amplifiers (Page 11) Project Analog - April 2008 - Accelerating Design of >50-W Class D Amplifiers (Page 12) Project Analog - April 2008 - Driving Power MOSFETs in Switch Mode Power Supplies (Page 13) Project Analog - April 2008 - Driving Power MOSFETs in Switch Mode Power Supplies (Page 14) Project Analog - April 2008 - Driving Power MOSFETs in Switch Mode Power Supplies (Page 15) Project Analog - April 2008 - Synergistic MOSFET Solutions (Page 16) Project Analog - April 2008 - Synergistic MOSFET Solutions (Page 17) Project Analog - April 2008 - Synergistic MOSFET Solutions (Page 18) Project Analog - April 2008 - Trends in MOSFET Gate Drivers (Page 19) Project Analog - April 2008 - Trends in MOSFET Gate Drivers (Page 20) Project Analog - April 2008 - Trends in MOSFET Gate Drivers (Page 21) Project Analog - April 2008 - Analog News—Analog news from multiple sources (Page 22) Project Analog - April 2008 - Contact Project Analog Sponsor (Page 23) Project Analog - April 2008 - Treelink (Page 24) Project Analog - April 2008 - Microchip Advanced Parts Selector (MAPS) (Page 25) Project Analog - April 2008 - Microchip Advanced Parts Selector (MAPS) (Page 26) Project Analog - April 2008 - Microchip Advanced Parts Selector (MAPS) (Page 27) Project Analog - April 2008 - Microchip Advanced Parts Selector (MAPS) (Page 28) Project Analog - April 2008 - Microchip Advanced Parts Selector (MAPS) (Page 29) Project Analog - April 2008 - Microchip Advanced Parts Selector (MAPS) (Page 30) Project Analog - April 2008 - Microchip Advanced Parts Selector (MAPS) (Page 31)
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