Many applications for the DLP® Digital Micromirror Device (DMD) use Continuous Wave (CW) illumination. Under CW illumination conditions, the temperature rise of the DMD is straightforward to calculate, and equations needed are provided in the data sheet for each DMD. There are also applications where pulsed illumination is used. The temperature rise of the DMD is more complicated to calculate with pulsed illumination, but is important to understand to make sure the DMD micromirror temperature is kept within a reliable operating range. The time required for DMD mirror heating can be longer than the pulse duration of the optical source, creating the need for a transient thermal model instead of a steady-state thermal model to accurately calculate the thermal rise at the DMD mirror surface. This application note describes the equations necessary for calculating DMD mirror surface temperature rise and DMD mirror bulk temperature rise as a function of pulse duration and pulse rate of the optical source.