LP38859-1.2EVAL National Semiconductor, LP38859-1.2EVAL Datasheet - Page 12

• Manufacturer Part Number: LP38859-1.2EVAL
• Description: BOARD EVALUATION LP38859-1.2
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LP38859-1.2EVAL

• Channels Per Ic: 1 - Single
• Voltage - Output: 1.2V
• Current - Output: 3A
• Voltage - Input: 3 ~ 5.5V
• Regulator Type: Positive Fixed
• Operating Temperature: -40°C ~ 125°C
• Board Type: Fully Populated
• Utilized Ic / Part: LP38859
• Lead Free Status / RoHS Status: Not applicable / Not applicable

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Heat-Sinking The TO-263 Package
The TO-263 package has a θ
rating of 3°C/W. These ratings are for the package only, no
additional heat-sinking, and with no airflow.
The TO-263 package uses the copper plane on the PCB as
a heat-sink. The tab of this package is soldered to the copper
plane for heat sinking. shows a curve for the θ
package for different copper area sizes, using a typical PCB
with 1 ounce copper and no solder mask over the copper area
for heat-sinking.
FIGURE 2. θ
JA
vs Copper (1 Ounce) Area for the TO-263
package
JA
rating of 60°C/W, and a θ
JA
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of TO-263
JC
12
Figure 2 shows that increasing the copper area beyond 1
square inch produces very little improvement. The minimum
value for θ
32°C/W.
Figure 3 shows the maximum allowable power dissipation for
TO-263 packages for different ambient temperatures, assum-
ing θ
125°C.
FIGURE 3. Maximum power dissipation vs ambient
JA
is 35°C/W and the maximum junction temperature is
temperature for the TO-263 package
JA
for the TO-263 package mounted to a PCB is
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