LP3881 Datasheet, PDF (11/18 Pages) National Semiconductor (TI) – 0.8A Fast-Response Ultra Low Dropout Linear Regulators

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LP3881
SNVS224F – MARCH 2003 – REVISED APRIL 2013
Figure 21. Maximum power dissipation vs ambient temperature for TO-263 package
HEATSINKING SOIC PACKAGE
Heatsinking for the SOIC-8 package is accomplished by allowing heat to flow through the ground slug on the
bottom of the package into the copper on the PC board. The heat slug must be soldered down to a copper plane
to get good heat transfer. It can also be connected through vias to internal copper planes. Since the heat slug is
at ground potential, traces must not be routed under it which are not at ground potential. Under all possible
conditions, the junction temperature must be within the range specified under operating conditions.
Figure 22 shows a curve for the θ_JA of the SOIC package for different copper area sizes using a typical PCB with
one ounce copper in still air.
180
130
80
30
0
0.5
1
1.5
COPPER AREA (sq. in.)
Figure 22. θ_JA vs. Copper (1 ounce) Area for SOIC Package
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