LP3853ET-33 Datasheet, PDF (16/25 Pages) Texas Instruments – LP3853/LP3856 3A Fast Response Ultra Low Dropout Linear Regulators

LP3853, LP3856
SNVS173G – FEBRUARY 2003 – REVISED APRIL 2013
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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 32 shows a curve for the θ_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.
Figure 32. θ_JA vs Copper (1 Ounce) Area for TO-263 package
As shown in the figure, increasing the copper area beyond 1 square inch produces very little improvement. The
minimum value for θ_JA for the TO-263 package mounted to a PCB is 32°C/W.
Figure 33 shows the maximum allowable power dissipation for TO-263 packages for different ambient
temperatures, assuming θ_JA is 35°C/W and the maximum junction temperature is 125°C.
Figure 33. Maximum power dissipation vs ambient temperature for TO-263 package
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