Datasheet

SBVS025G
REG104
12
FIGURE 10. Thermal Resistance versus PCB Area for the Five-Lead DDPAK.
FIGURE 11. Thermal Resistance versus PCB Area for the Five Lead SOT-223.
50
40
30
20
10
0
Thermal Resistance, θ
JA
(°C/W)
012345
Copper Area (inches
2
)
REG104
Surface Mount Package
1 oz. copper
Circuit Board Copper Area
REG104
DDPAK Surface Mount Package
THERMAL RESISTANCE vs PCB COPPER AREA
THERMAL RESISTANCE vs PCB COPPER AREA
180
160
140
120
100
80
60
40
20
0
Thermal Resistance,
JA
(°C/W)
θ
012345
Copper Area (inches
2
)
Circuit Board Copper Area
REG104
SOT-223 Surface Mount Package
REG104
Surface Mount Package
1 oz. copper
REGULATOR MOUNTING
The tab of both packages is electrically connected to ground.
For best thermal performance, the tab of the DDPAK sur-
face-mount version should be soldered directly to a circuit-
board copper area. Increasing the copper area improves
heat dissipation. Figure 10 shows typical thermal resistance
from junction to ambient as a function of the copper area for
the DDPAK. Figure 11 shows the same relationship for the
SOT-223.
Although the tabs of the DDPAK and the SOT-223 are
electrically grounded, they are not intended to carry any
current. The copper pad that acts as a heat sink should be
isolated from the rest of the circuit to prevent current flow
through the device from the tab to the ground pin. Solder pad
footprint recommendations for the various REG104 devices
are presented in the Application Bulletin
Solder Pad Recom-
mendations for Surface-Mount Devices
(SBFA015A), avail-
able from the Texas Instruments web site (www.ti.com).