LP3966ES-5.0 datasheet(15/17 Pages) NSC

Part #	LP3966ES-5.0

Description	3A Fast Ultra Low Dropout Linear Regulators

PDF	17 Pages

Scroll/Zoom	100%

Manufacturer	NSC [National Semiconductor (TI)]

Direct Link	http://www.national.com

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15 / 17 page

Application Hints (Continued)

HEATSINKING TO-263 PACKAGE

The TO-263 package uses the copper plane on the PCB as

a heatsink. The tab of these packages are soldered to the

copper plane for heat sinking. Figure 3 shows a curve for the

JA of TO-263 package for different copper area sizes, using

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

JA for the TO-263 package mounted to a PCB is

32˚C/W.

Figure 4 shows the maximum allowable power dissipation

for TO-263 packages for different ambient temperatures,

assuming

JA is 35˚C/W and the maximum junction tempera-

ture is 125˚C.

10126732

FIGURE 3.

JA vs Copper (1 Ounce) Area for TO-263

package

10126733

FIGURE 4. Maximum power dissipation vs ambient

temperature for TO-263 package

LP3966ES-5.0 Datasheet(PDF) 15 Page - National Semiconductor (TI)