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參數(shù)資料
| 型號： | LP3883ET-1.8/NOPB |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 固定正電壓單路輸出LDO穩(wěn)壓器 |
| 英文描述： | 1.8 V FIXED POSITIVE LDO REGULATOR, 0.42 V DROPOUT, PZFM5 |
| 封裝： | TO-220, 5 PIN |
| 文件頁數(shù)： | 3/14頁 |
| 文件大?。?/td> | 819K |
| 代理商： | LP3883ET-1.8/NOPB |
Application Hints (Continued)
POWER DISSIPATION/HEATSINKING
A heatsink may be required depending on the maximum
power dissipation and maximum ambient temperature of the
application. Under all possible conditions, the junction tem-
perature must be within the range specified under operating
conditions. The total power dissipation of the device is given
by:
P
D =(VINVOUT)IOUT+(VIN)IGND
where I
GND is the operating ground current of the device.
The maximum allowable temperature rise (T
Rmax) depends
on the maximum ambient temperature (T
Amax) of the appli-
cation, and the maximum allowable junction temperature
(T
Jmax):
T
Rmax =TJmaxTAmax
The maximum allowable value for junction to ambient Ther-
mal Resistance,
θ
JA, can be calculated using the formula:
θ
JA =TRmax /PD
These parts are available in TO-220 and TO-263 packages.
The thermal resistance depends on amount of copper area
or heat sink, and on air flow. If the maximum allowable value
of
θ
JA calculated above is
≥ 60 C/W for TO-220 package
and
≥ 60 C/W for TO-263 package no heatsink is needed
since the package can dissipate enough heat to satisfy these
requirements. If the value for allowable
θ
JA falls below these
limits, a heat sink is required.
HEATSINKING TO-220 PACKAGE
The thermal resistance of a TO220 package can be reduced
by attaching it to a heat sink or a copper plane on a PC
board. If a copper plane is to be used, the values of
θ
JA will
be same as shown in next section for TO263 package.
The heatsink to be used in the application should have a
heatsink to ambient thermal resistance,
θ
HA
≤θ
JA
θ
CH
θ
JC.
In this equation,
θ
CH is the thermal resistance from the case
to the surface of the heat sink and
θ
JC is the thermal resis-
tance from the junction to the surface of the case.
θ
JC is
about 3C/W for a TO220 package. The value for
θ
CH de-
pends on method of attachment, insulator, etc.
θ
CH varies
between 1.5C/W to 2.5C/W. If the exact value is unknown,
2C/W can be assumed.
HEATSINKING TO-263 PACKAGE
The TO-263 package uses the copper plane on the PCB as
a heatsink. The tab of these packages are soldered to the
copper plane for heat sinking. The graph below shows a
curve for the
θ
JA of TO-263 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.
20062425
FIGURE 1.
θ
JA vs Copper (1 Ounce) Area for TO-263
package
LP3883
www.national.com
11
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LP38841 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:0.8A Ultra Low Dropout Linear Regulators Stable with Ceramic Output Capacitors |
| LP38841-ADJ | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:0.8A Ultra Low Dropout Adjustable Linear Regulators Stable with Ceramic Output Capacitors |
| LP38841EVAL | 功能描述:電源管理IC開發(fā)工具 LP38841 EVAL BOARD RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| LP38841MR | 制造商:Rochester Electronics LLC 功能描述: 制造商:Texas Instruments 功能描述: |
| LP38841MR-ADJ | 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 |
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