LP3883

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SNVS223F – NOVEMBER 2002 – REVISED APRIL 2013

(6)

These parts are available in TO-220 and DDPAK/TO-263 packages. The thermal resistance depends on amount

of copper area or heat sink, and on air flow. If the maximum allowable value of

for TO-220 package and

≥ 60 °C/W for DDPAK/TO-263 package no heatsink is needed since the package can

dissipate enough heat to satisfy these requirements. If the value for allowable

sink is required.

HEATSINKING TO-220 PACKAGE

The thermal resistance of a TO220 package can be reduced by attaching it to a heat sink or a copper plane on a

PC board. If a copper plane is to be used, the values of

package.

The heatsink to be used in the application should have a heatsink to ambient thermal resistance,

(7)

In this equation,

resistance from the junction to the surface of the case.

is unknown, 2°C/W can be assumed.

HEATSINKING DDPAK/TO-263 PACKAGE

The DDPAK/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. The graph below shows a curve for the

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.

Figure 34.

As shown in the graph below, increasing the copper area beyond 1 square inch produces very little improvement.

The minimum value for

Figure 35 shows the maximum allowable power dissipation for DDPAK/TO-263 packages for different ambient

temperatures, assuming

Figure 35. Maximum power dissipation vs ambient temperature for DDPAK/TO-263 package

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