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LM340, LM340A, LM7805, LM7812, LM7815

SNOSBT0L – FEBRUARY 2000 – REVISED SEPTEMBER 2016

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Product Folder Links: LM340 LM340A LM7805 LM7812 LM7815

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Copyright © 2000–2016, Texas Instruments Incorporated

Layout Example (continued)

Figure 28. Layout Example SOT-223

10.3 Heat Sinking DDPAK/TO-263 and SOT-223 Package Parts

Both the DDPAK/TO-263 (KTT) and SOT-223 (DCY) packages use a copper plane on the PCB and the PCB

itself as a heat sink. To optimize the heat sinking ability of the plane and PCB, solder the tab of the plane.

Figure 29 shows for the DDPAK/TO-263 the measured values of θ(J–A) for different copper area sizes using a

typical PCB with 1-oz copper and no solder mask over the copper area used for heat sinking.

Figure 29. θ(J–A) vs Copper (1 Ounce) Area for the DDPAK/TO-263 Package