LP38853_15 Datasheet, PDF (17/28 Pages) Texas Instruments – LP38853 3A Fast-Response High-Accuracy Adjustable LDO Linear Regulator with Enable and Soft-Start

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LP38853
SNVS335D – DECEMBER 2006 – REVISED APRIL 2013
5
PFM Package
1 Sq Inch of 1 oz. Copper
4
q_JA = 35°C/W
3
2
T_J < 125°C
T_J=125°C
1
Figure 33. θ_JA vs Copper (1 Ounce) Area for the
DDPAK package
0
–50 –25 0 25 50 75 100 125
AMBIENT TEMPERATURE (°C)
Figure 34. 101Maximum Power Dissipation vs
Ambient Temperature for the DDPAK Package
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.
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.
Figure 36 shows the maximum allowable power dissipation for the SO PowerPAD-8 package for a range of
ambient temperatures, assuming θ_JA is 98°C/W and the maximum junction temperature is 125°C.
Figure 35. θ_JA vs Copper (1 Ounce) Area for the SO Figure 36. Maximum Power Dissipation vs Ambient
PowerPAD-8 Package
Temperature for the SO PowerPAD-8 Package
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