LP3964ET-1.8/NOPB National Semiconductor, LP3964ET-1.8/NOPB Datasheet - Page 16

• Manufacturer Part Number: LP3964ET-1.8/NOPB
• Description: IC REGULATOR ULTR LDO TO-220-5
• Manufacturer: National Semiconductor

Specifications of LP3964ET-1.8/NOPB

• Regulator Topology: Positive Fixed
• Voltage - Output: 1.8V
• Voltage - Input: 2.5 ~ 7 V
• Number Of Regulators: 1
• Current - Output: 800mA
• Current - Limit (min): 1.2A
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Through Hole
• Package / Case: TO-220-5 (Bent and Staggered Leads)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Dropout (typical): -
• Other names: *LP3964ET-1.8; *LP3964ET-1.8/NOPB; LP3964ET-1.8

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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
JA
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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10112933
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
JA
vs Copper(1 Ounce) Area for SOT-223
package
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JA
= 148˚C/W
= 125˚C/W
10112919
10112921
10112920