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參數(shù)資料
| 型號： | LP3881ET-1.8 |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 基準(zhǔn)電壓源/電流源 |
| 英文描述： | 0.8A Fast-Response Ultra Low Dropout Linear |
| 中文描述： | 1.8 V FIXED POSITIVE LDO REGULATOR, 0.16 V DROPOUT, PZFM5 |
| 封裝： | MOLDED, STAGGER BEND, TO-220, 5 PIN |
| 文件頁數(shù)： | 9/12頁 |
| 文件大?。?/td> | 318K |
| 代理商： | LP3881ET-1.8 |
Application Hints
(Continued)
UNDER VOLTAGE LOCKOUT
The bias voltage is monitored by a circuit which prevents the
regulator output from turning on if the bias voltage is below
approximately 4V.
SHUTDOWN OPERATION
Pulling down the shutdown (S/D) pin will turn-off the regula-
tor. Pin S/D must be actively terminated through a pull-up
resistor (10 k
to 100 k
) for a proper operation. If this pin
is driven from a source that actively pulls high and low (such
as a CMOS rail to rail comparator), the pull-up resistor is not
required. This pin must be tied to Vin if not used.
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
= (V
IN
V
OUT
)I
OUT
+ (V
IN
)I
GND
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
= T
Jmax
T
Amax
The maximum allowable value for junction to ambient Ther-
mal Resistance,
θ
JA
, can be calculated using the formula:
θ
JA
= T
Rmax
/ P
D
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
is the thermal resistance from the case
to the surface of the heat sink and
θ
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
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.
20063025
FIGURE 1.
θ
JA
vs Copper (1 Ounce) Area for TO-263
package
L
www.national.com
9
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LP3882 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:1.5A Fast-Response Ultra Low Dropout Linear |
| LP3882EMR-1.2 | 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 |
| LP3882EMR-1.2/NOPB | 功能描述:低壓差穩(wěn)壓器 - LDO High Performance Dual-Rail 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 |
| LP3882EMR-1.2/NOPB | 制造商:Texas Instruments 功能描述:Voltage Regulator IC |
| LP3882EMR-1.5 | 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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