LM340-N, LM78xx
www.ti.com
SNOSBT0I –FEBRUARY 2000–REVISED MARCH 2013
Operating Conditions(1) (continued)
LM140
−55°C to +125°C
0°C to +125°C
0°C to +125°C
Temperature Range (TA)(2)
LM340A, LM340-N
LM7808C
(2) The maximum allowable power dissipation at any ambient temperature is a function of the maximum junction temperature for operation
(TJMAX = 125°C or 150°C), the junction-to-ambient thermal resistance (θJA), and the ambient temperature (TA). PDMAX = (TJMAX
−
TA)/θJA. If this dissipation is exceeded, the die temperature will rise above TJMAX and the electrical specifications do not apply. If the die
temperature rises above 150°C, the device will go into thermal shutdown. For the TO-3 package (NDS), the junction-to-ambient thermal
resistance (θJA) is 39°C/W. When using a heatsink, θJA is the sum of the 4°C/W junction-to-case thermal resistance (θJC) of the TO-3
package and the case-to-ambient thermal resistance of the heatsink. For the TO-220 package (NDE), θJA is 54°C/W and θJC is 4°C/W. If
SOT-223 is used, the junction-to-ambient thermal resistance is 174°C/W and can be reduced by a heatsink (see Applications Hints on
heatsinking).If the DDPAK\TO-263 package is used, the thermal resistance can be reduced by increasing the PC board copper area
thermally connected to the package: Using 0.5 square inches of copper area, θJA is 50°C/W; with 1 square inch of copper area, θJAis
37°C/W; and with 1.6 or more inches of copper area, θJA is 32°C/W.
Copyright © 2000–2013, Texas Instruments Incorporated
Submit Documentation Feedback
3
Product Folder Links: LM340-N LM78xx
TI [ TEXAS INSTRUMENTS ]
