The external FET transistor, used for the external current limit (see Section 6.3.3), is the most significant source of heat. The power dissipated by the external FET is a direct function of the maximum power supply voltage and maximum current output range supported in the application. Select a FET transistor that supports the maximum drain to source voltage and maximum power required; see also Section 6.3.4. Refer to the FET manufacturer for information on component placement requirements and heat sink selection.

The XTR111 only generates heat from the supply voltage with the quiescent current, the internal signal current that is 1/10 of the output current, and the current and internal voltage drop of the regulator.

The exposed thermal pad on the bottom of the XTR111 package allows excellent heat dissipation of the device into the printed circuit board (PCB).