This is the second in a series of application notes that definethe fundamental behavior of MOSFETs, both as standalonedevices and as switching devices implemented in aswitchmode power supply (SMPS). The first application note1provided a basic des cription of the MOSFET and theterminology behind the device, including definitions andphysical structure. This application note goes into more detailon the switching behavior of the MOSFET when used in apractical application circuit and attempts to enable thereader/designer to choose the right device for the applicationusing the minimum available information from the datasheet.The note goes through several methods of assessing theswitching performance of the MOSFET and compares thesemethods against practical results. Several definitions usedwithin the text are drawn from application note AN605.