LP38842 Datasheet, PDF (9/11 Pages) National Semiconductor (TI) – 1.5A Ultra Low Dropout Linear Regulators Stable with Ceramic Output Capacitors

Application Hints (Continued)
Figure 2 shows the maximum allowable power dissipation
for TO-263 packages for different ambient temperatures,
assuming θ_JA is 35˚C/W and the maximum junction tempera-
ture is 125˚C.
20103025
FIGURE 1. θ_JA vs Copper (1 Ounce) Area for TO-263
package
As shown in the graph below, increasing the copper area
beyond 1 square inch produces very little improvement. The
minimum value for θ_JA for the TO-263 package mounted to a
PCB is 32˚C/W.
20103026
FIGURE 2. Maximum power dissipation vs ambient
temperature for TO-263 package
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