LM340T-12 National Semiconductor, LM340T-12 Datasheet - Page 12
![IC, LINEAR VOLT REGULATOR, 12V, TO-220-3](/photos/19/7/190743/3833580_sml.gif)
LM340T-12
Manufacturer Part Number
LM340T-12
Description
IC, LINEAR VOLT REGULATOR, 12V, TO-220-3
Manufacturer
National Semiconductor
Datasheet
1.LM340MP-5.0NOPB.pdf
(17 pages)
Specifications of LM340T-12
Primary Input Voltage
27V
Output Voltage Fixed
12V
Dropout Voltage Vdo
2V
No. Of Outputs
1
No. Of Pins
3
Output Current
1A
Operating Temperature Range
0°C To +125°C
Current Rating
1A
Rohs Compliant
No
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Part Number:
LM340T-12
Manufacturer:
NS/国半
Quantity:
20 000
Part Number:
LM340T-12/NOPB
Manufacturer:
NS/国半
Quantity:
20 000
www.national.com
Application Hints
HEATSINKING TO-263 AND SOT-223 PACKAGE PARTS
Both the TO-263 (“S”) and SOT-223 (“MP”) packages use a
copper plane on the PCB and the PCB itself as a heatsink.
To optimize the heat sinking ability of the plane and PCB,
solder the tab of the plane.
shows for the TO-263 the measured values of θ
different copper area sizes using a typical PCB with 1 ounce
copper and no solder mask over the copper area used for
heatsinking.
As shown in the figure, increasing the copper area beyond 1
square inch produces very little improvement. It should also
be observed that the minimum value of θ
package mounted to a PCB is 32˚C/W.
As a design aid, Figure 5 shows the maximum allowable
power dissipation compared to ambient temperature for the
TO-263 device (assuming θ
mum junction temperature is 125˚C).
FIGURE 5. Maximum Power Dissipation vs
FIGURE 4. θ
T
Area for the TO-263 Package
AMB
for the TO-263 Package
(J–A)
vs Copper (1 ounce)
(J–A)
(Continued)
is 35˚C/W and the maxi-
(J–A)
00778139
for the TO-263
00778140
(J–A)
for
12
Figures 6, 7 show the information for the SOT-223 package.
Figure 6 assumes a θ
51˚C/W for 2 ounce copper and a maximum junction tem-
perature of 125˚C.
Please see AN-1028 for power enhancement techniques to
be used with the SOT-223 package.
FIGURE 6. θ
FIGURE 7. Maximum Power Dissipation vs
T
AMB
for the SOT-223 Package
for the SOT-223 Package
(J–A)
(J–A)
vs Copper (2 ounce) Area
of 74˚C/W for 1 ounce copper and
00778141
00778142