Datasheet

AMBIENT TEMPERATURE (°C)
–50
–25 0 25 50 75 100 125
PFM Package
1 Sq Inch of 1 oz. Copper
q
JA
= 35°C/W
T
J
=125°C
T
J
< 125°C
5
4
3
2
1
0
MAXIMUM POWER DISSIPATION (W)
LP38853
www.ti.com SNVS335D –DECEMBER 2006–REVISED APRIL 2013
Figure 33. θ
JA
vs Copper (1 Ounce) Area for the Figure 34. 101Maximum Power Dissipation vs
DDPAK package 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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