If the DDPAK/TO-263 package is used, the thermal resistance can be reduced by increasing the PCB copper area thermally connected to the package. Using 0.5 square inches of copper area, θJA is 50°C/W, with 1 square inch of copper area, θJA is 37°C/W, and with 1.6 or more square inches of copper area, θJA is 32°C/W.
Figure 6-17 Maximum Power Dissipation (DDPAK/TO-263)