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參數(shù)資料
| 型號： | LM2940IMP |
| 廠商： | National Semiconductor Corporation |
| 元件分類： | 基準(zhǔn)電壓源/電流源 |
| 英文描述： | Cap-Free, NMOS, 150mA Low Dropout Regulator with Reverse Current Protection |
| 中文描述： | 無電容，NMOS管，150mA的低壓差穩(wěn)壓器的反向電流保護(hù) |
| 文件頁數(shù)： | 14/20頁 |
| 文件大?。?/td> | 410K |
| 代理商： | LM2940IMP |
θ
(
CH)
is defined as the thermal resistance between
the case and the surface of the heatsink. The
value of
θ
(
will vary from about 1.5°C/W to
about 2.5°C/W (depending on method of at-
tachment, insulator, etc.). If the exact value is
unknown, 2°C/W should be assumed for
θ
(
C
H)
.
When a value for
θ
(
is found using the equation shown,
a
heatsink must be selected that has a value that is less than
or equal to this number.
θ
(
is specified numerically by the heatsink manufacturer
in the catalog, or shown in a curve that plots temperature rise
vs power dissipation for the heatsink.
HEATSINKING TO-263 PACKAGE PARTS
The TO-263 (“S”) package uses 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 package to
the plane.
Figure 3
shows for the TO-263 the measured values of
θ
(
for different copper area sizes using a typical PCB with 1
ounce copper
and no solder mask over the copper area used
for heatsinking.
882238
FIGURE 3.
θ
(
JA)
vs. Copper (1 ounce) Area for the TO-263
Package
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
(
JA)
for the TO-263
package mounted to a PCB is 32°C/W.
As a design aid,
Figure 4
shows the maximum allowable pow-
er dissipation compared to ambient temperature for the
TO-263 device. This assumes a
θ
(
of 35°C/W for 1 square
inch of 1 ounce copper and a maximum junction temperature
(T
J
) of 125°C.
882239
FIGURE 4. Maximum Power Dissipation vs. T
A
for the
TO-263 Package
HEATSINKING SOT-223 PACKAGE PARTS
The 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
package to the plane.
Figure 5
and
Figure 6
show the information for the SOT-223
package.
Figure 6
assumes a
θ
(
of 74°C/W for 1 square
inch of 1 ounce copper and 51°C/W for 1 square inch of 2
ounce copper, with a maximum ambient temperature (T
A
) of
85°C and a maximum junction temperature (T
J
) of 125°C.
For techniques for improving the thermal resistance and pow-
er dissipation for the SOT-223 package, please refer to Ap-
plication Note AN-1028.
882240
FIGURE 5.
θ
(
JA)
vs. Copper (2 ounce) Area for the SOT-223
Package
www.national.com
14
L
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM2940IMP-10 | 功能描述:低壓差穩(wěn)壓器 - LDO RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓（最大值）:307 mV 輸出電流:1 A 負(fù)載調(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| LM2940IMP-10/NOPB | 功能描述:低壓差穩(wěn)壓器 - LDO RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓（最大值）:307 mV 輸出電流:1 A 負(fù)載調(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| LM2940IMP-10/NOPB | 制造商:Texas Instruments 功能描述:Linear Voltage Regulator IC |
| LM2940IMP-12 | 功能描述:低壓差穩(wěn)壓器 - LDO RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓（最大值）:307 mV 輸出電流:1 A 負(fù)載調(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| LM2940IMP-12/LF01 | 制造商:Texas Instruments 功能描述:LDO Regulator Pos 12V 1A 4-Pin(3+Tab) SOT-223 T/R |
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