LM340 datasheet(19/33 Pages) TI1

19 / 33 page

LM340, LM340A, LM7805, LM7812, LM7815

www.ti.com

SNOSBT0K – FEBRUARY 2000 – REVISED JULY 2016

Product Folder Links: LM340 LM340A LM7805 LM7812 LM7815

Submit Documentation Feedback

Heat Sinking DDPAK/TO-263 and SOT-223 Package Parts (continued)

As shown in Figure 29, increasing the copper area beyond 1 square inch produces very little improvement. It

should also be observed that the minimum value of θ(J–A) for the DDPAK/TO-263 package mounted to a PCB is

32°C/W.

As a design aid, Figure 30 shows the maximum allowable power dissipation compared to ambient temperature

for the DDPAK/TO-263 device (assuming θ(J–A) is 35°C/W and the maximum junction temperature is 125°C).

Figure 30. Maximum Power Dissipation vs TAMB for the DDPAK/TO-263 Package

Figure 31 and Figure 32 show the information for the SOT-223 package. Figure 31 assumes a θ(J–A) of 74°C/W

for 1-oz. copper and 51°C/W for 2-oz. copper and a maximum junction temperature of 125°C.

Figure 31. θ(J–A) vs Copper (2 Ounce) Area

for the SOT-223 Package

Figure 32. Maximum Power Dissipation vs

TAMB for the SOT-223 Package

See AN-1028 LMX2370 PLLatinum Dual Freq Synth for RF Pers Comm LMX2370 2.5GHz/1.2GHz (SNVA036)

for power enhancement techniques to be used with the SOT-223 package.

LM340 Datasheet(PDF) 19 Page - Texas Instruments