Power MOSFETs are commonplace in modern electronic circuit design, where they are frequently used to switch loads of many different types – ranging from a few milliamps or less to several tens of amps, depending on application. The popularity of power MOSFETs is almost certainly attributable to their ease of drive compared to their bipolar counterparts, together with the wide range of package, voltage and RDS(on) combinations which are now available. Of course, MOSFETs are not perfect switches and neither are they indestructible, and the circuit designer should be aware of the following thermal considerations when designing a system employing MOSFET devices