Assume that an external ballast transistor is being used for linear voltage regulation of a µ-Controller. Including some safety margins Ptot is required to be around 700 mW. A multi-layer PCB is used and the package of the transistor shall be as small as possible to limit the size and the costs of the PCB. In the past, SOT89 or SOT223 were the packages of choice, mounted on single layer PCB. The DFN2020D-3 package from NXP mounted on a 4-layer PCB requires less than 1/12 of the footprint of a SOT223, while running even cooler in the same application.