LP38853_14 Datasheet, PDF (17/27 Pages) Texas Instruments – 3A Fast-Response High-Accuracy Adjustable LDO Linear Regulator with Enable and Soft-Start

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LP38853
SNVS335C – DECEMBER 2006 – REVISED SEPTEMBER 2011
Figure 34. Maximum Power Dissipation vs Ambient Temperature for the DDPAK Package
Figure 34 shows the maximum allowable power dissipation for DDPAK packages for different ambient
temperatures, assuming θ_JA is 35°C/W and the maximum junction temperature is 125°C.
Heat-Sinking The SO PowerPAD-8 Package
The LP38853MR package has a θ_JA rating of 168°C/W, and a θ_JC rating of 11°C/W. The θ_JA rating of 168°C/W
includes the device DAP soldered to an area of 0.008 square inches (0.09 in x 0.09 in) of 1 ounce copper, with
no airflow.
Figure 35. θ_JA vs Copper (1 Ounce) Area for the SO PowerPAD-8 Package
Increasing the copper area soldered to the DAP to 1 square inch of 1 ounce copper, using a dog-bone type
layout, will improve the θ_JA rating to 98°C/W. Figure 35 shows that increasing the copper area beyond 1 square
inch produces very little improvement.
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