LP3961EMP-3.3 National Semiconductor, LP3961EMP-3.3 Datasheet - Page 16

• Manufacturer Part Number: LP3961EMP-3.3
• Manufacturer: National Semiconductor

Specifications of LP3961EMP-3.3

• Voltage Regulator Type: Linear
• Topology: LDO
• Regulator Output Type: Fixed
• Polarity Type: Positive
• Number Of Outputs: Single
• Input Voltage (min): 2.5V
• Input Voltage (max): 7V
• Output Voltage: 3.3V
• Package Type: SOT-223
• Output Current: 800mA
• Load Regulation: 0.02%
• Line Regulation: 0.02%
• Output Voltage Accuracy: ±1.5%
• Operating Temp Range: -40C to 125C
• Operating Temperature Classification: Automotive
• Dropout Voltage@current (max): 0.03@80mA/0.3@800mA
• Pin Count: 4 +Tab
• Mounting: Surface Mount
• Lead Free Status / Rohs Status: Not Compliant

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Application Hints
HEATSINKING TO-263 AND SOT-223 PACKAGES
The TO-263 and SOT223 packages use the copper plane on
the PCB as a heatsink. The tab of these packages are
soldered to the copper plane for heat sinking. Figure 3
shows a curve for the θ
copper area sizes, using a typical PCB with 1 ounce copper
and no solder mask over the copper area for heat sinking.
As shown in the figure, increasing the copper area beyond 1
square inch produces very little improvement. The minimum
value for θ
32˚C/W.
Figure 4 shows the maximum allowable power dissipation
for TO-263 packages for different ambient temperatures,
assuming θ
ture is 125˚C.
Figure 5 shows a curve for the θ
different copper area sizes, using a typical PCB with 1 ounce
copper and no solder mask over the copper area for heat
sinking.
FIGURE 3. θ
FIGURE 4. Maximum power dissipation vs ambient
JA
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temperature for TO-263 package
for the TO-263 packag mounted to a PCB is
is 35˚C/W and the maximum junction tempera-
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vs Copper(1 Ounce) Area for TO-263
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package
of TO-263 package for different
(Continued)
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of SOT-223 package for
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16
The following figures show different layout scenarios for
SOT-223 package.
FIGURE 5. θ
FIGURE 6. SCENARIO A, θ
FIGURE 7. SCENARIO B, θ
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vs Copper(1 Ounce) Area for SOT-223
package
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JA
= 148˚C/W
= 125˚C/W
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10112921
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