LM340T-12/NOPB National Semiconductor, LM340T-12/NOPB Datasheet - Page 12

• Manufacturer Part Number: LM340T-12/NOPB
• Description: IC REGULATOR POSIT 12V TO220-3
• Manufacturer: National Semiconductor
• Type: Voltage Regulatorr

Specifications of LM340T-12/NOPB

• Regulator Topology: Positive Fixed
• Voltage - Output: 12V
• Voltage - Input: 14.6 ~ 35 V
• Voltage - Dropout (typical): 2V @ 1A
• Number Of Regulators: 1
• Current - Output: 1.5A
• Current - Limit (min): 2.4A
• Operating Temperature: 0°C ~ 125°C
• Mounting Type: Through Hole
• Package / Case: TO-220-3 (Straight Leads)
• Current, Output: 1 A
• Current, Supply: 6 mA
• Package Type: TO-220
• Regulation, Line: 4 mV
• Regulation, Load: 12 mV
• Regulator Type: Positive Voltage Out
• Resistance, Thermal, Junction To Case: 4 °C/W
• Temperature, Operating, Range: 0 to +125 °C
• Voltage, Dropout: 2 V
• Voltage, Input: 19 V
• Voltage, Noise: 75 μV
• Voltage, Output: 12 V
• Voltage, Supply, Rejection Ratio: 72 dB
• Primary Input Voltage: 27V
• Output Voltage Fixed: 12V
• No. Of Outputs: 1
• No. Of Pins: 3
• Output Current: 1A
• Operating Temperature Range: 0°C To +125°C
• Msl: MSL 1 - Unlimited
• Current Rating: 1A
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: *LM340T-12; *LM340T-12/NOPB; LM340T-12; LM7812; LM7812CT; LM7812T; UA7812; UA7812CT; UA7812CU

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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)
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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