LP38511_14 Datasheet, PDF (12/19 Pages) Texas Instruments – 800 mA Fast-Transient Response Low-Dropout Linear Voltage Regulator with Error Flag

LP38511
SNOSAU6D – NOVEMBER 2007 – REVISED MARCH 2009
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HEATSINKING DDPAK/TO-263 PACKAGE
The DDPAK/TO-263 and the PFM packages use the copper plane on the PCB as a heatsink. The tab, or DAP,
of these packages are soldered to the copper plane for heat sinking. Figure 25 shows a curve for the θ_JA of
DDPAK/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 25. θ_JA vs Copper (1 Ounce) Area for DDPAK/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 DDPAK/TO-263 package mounted to a two-layer PCB is 32°C/W.
Figure 26 shows the maximum allowable power dissipation for DDPAK/TO-263 packages for different ambient
temperatures, assuming θ_JA is 35°C/W and the maximum junction temperature is 125°C.
Figure 26. Maximum Power Dissipation vs Ambient Temperature for DDPAK/TO-263 Package
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