Datasheet

1 oz. Copper
Power Plane
1 oz. Copper
Ground Plane
2 oz. Copper Solder Pad
with 25 Thermal Vias
Thermal Vias, 0,3 mm
Diameter, 1,5 mm Pitch
− Maximum Junction Temperature − 125
T
JM
C
°
1
2
3
4
5
0.1 1 10 100
− Maximum Power Dissipation − W
P
D
Copper Heatsink Area − cm
2
T
A
= 55°C
No Air Flow
150 LFM
250 LFM
P
D
max +
(
3.3 * 2.5
)
V x 1 A + 800 mW
TPS726126
TPS72615, TPS72616
TPS72618, TPS72625
www.ti.com SLVS403H –MAY 2002–REVISED JUNE 2010
Figure 21. DDPAK Thermal Resistance
From the data in Figure 22 and rearranging Equation 4, the maximum power dissipation for a different ground
plane area and a specific ambient temperature can be computed.
Figure 22. Maximum Power Dissipation vs Copper Heatsink Area
SOT223 Power Dissipation
The SOT223 package provides an effective means of managing power dissipation in surface mount applications.
The SOT223 package dimensions are provided in the Mechanical Data section at the end of the data sheet. The
addition of a copper plane directly underneath the SOT223 package enhances the thermal performance of the
package.
To illustrate, the TPS72625 in a SOT223 package was chosen. For this example, the average input voltage is
3.3 V, the output voltage is 2.5 V, the average output current is 1 A, the ambient temperature 55°C, no air flow is
present, and the operating environment is the same as documented below. Neglecting the quiescent current, the
maximum average power is:
(7)
Substituting T
J
max for T
J
into Equation 4 gives Equation 8:
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Product Folder Link(s): TPS726126 TPS72615 TPS72616 TPS72618 TPS72625