lp3855et-3.3 National Semiconductor Corporation, lp3855et-3.3 Datasheet - Page 16

• Manufacturer Part Number: lp3855et-3.3
• Description: 1.5a Fast Response Ultra Low Dropout Linear Regulators
• Manufacturer: National Semiconductor Corporation

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Application Hints
θ
a typical PCB with 1 ounce copper and no solder mask over
the copper area for heat sinking.
As shown in the figure, increasing the copper area beyond 1
square inch produces very little improvement. The minimum
value for θ
32˚C/W.
JA
FIGURE 5. θ
of TO-263 package for different copper area sizes, using
JA
for the TO-263 package mounted to a PCB is
JA
vs Copper (1 Ounce) Area for TO-263
package
(Continued)
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Figure 6 shows the maximum allowable power dissipation
for TO-263 packages for different ambient temperatures,
assuming θ
ture is 125˚C.
FIGURE 6. Maximum power dissipation vs ambient
JA
temperature for TO-263 package
is 35˚C/W and the maximum junction tempera-
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