Datasheet

R
θJA
max + (125 * 55)°Cń800 mW + 87.5°CńW
0
100
120
140
160
180
PCB Copper Area − in
2
− Thermal Resistance −
θJA
R C/W
°
No Air Flow
80
60
40
20
0.1 1 10
0
1
2
3
6
0 25 50 75 100 150
− Maximum Power Dissipation − W
P
D
125
T
A
= 25°C
T
A
− Ambient Temperature − °C
4
5
4 in
2
PCB Area
0.5 in
2
PCB Area
TPS726126
TPS72615, TPS72616
TPS72618, TPS72625
SLVS403H –MAY 2002–REVISED JUNE 2010 www.ti.com
(8)
From Figure 23, R
qJA
vs PCB Copper Area, the ground plane needs to be 0.55 in
2
for the part to dissipate 800
mW. The operating environment used to construct Figure 23 consisted of a board with 1 oz. copper planes. The
package is soldered to a 1 oz. copper pad on the top of the board. The pad is tied through thermal vias to the 1
oz. ground plane.
Figure 23. SOT223 Thermal Resistance vs PCB AREA
From the data in Figure 23 and rearranging Equation 4, the maximum power dissipation for a different ground
plane area and a specific ambient temperature can be computed (as shown in Figure 24).
Figure 24. SOT223 Power Dissipation
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