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參數(shù)資料
| 型號(hào)： | LT1521 |
| 廠商： | Linear Technology 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(wú)電容，NMOS管，150mA的低壓差穩(wěn)壓器的反向電流保護(hù) |
| 文件頁(yè)數(shù)： | 10/16頁(yè) |
| 文件大?。?/td> | 248K |
| 代理商： | LT1521 |
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LT1521/LT1521-3
LT1521-3.3/LT1521-5
output is turned off and the divider current will be zero.
Curves of Adjust Pin Voltage vs Temperature and Adjust
Pin Bias Current vs Temperature appear in the Typical
Performance Characteristics. The reference voltage at the
adjust pin has a positive temperature coefficient of ap-
proximately 15ppm/
°
C. The adjust pin bias current has a
negative temperature coefficient. These effects will tend to
cancel each other.
The adjustable device is specified with the adjust pin tied
to the output pin. This sets the output voltage to 3.75V.
Specifications for output voltages greater than 3.75V will
be proportional to the ratio of the desired output voltage
to 3.75V; (V
OUT
/3.75V). For example: load regulation for
an output current change of 1mA to 300mA is –20mV
typical at V
OUT
= 3.75V. At V
OUT
= 12V, load regulation
would be:
(12V/3.75V)(–20mV) = –64mV
Thermal Considerations
The power handling capability of the device will be limited
by the maximum rated junction temperature (125
°
C). The
power dissipated by the device will be made up of two
components:
1. Output current multiplied by the input/output voltage
differential: I
OUT
(V
IN
– V
OUT
), and
2. Ground pin current multiplied by the input voltage:
(I
GND
)(V
IN
)
APPLICATIO
S I
N
FOR
ATIO
U
W
U
Figure 2. Adjustable Operation
+
V
IN
V
OUT
LT1521
GND
IN
SHDN
OUT
ADJ
LT1521 F01
V
OUT
= 3.75V 1 + R1
ADJ
+ R2)
V
ADJ
= 3.75V
I
ADJ
= 50nA AT 25
°
C
OUTPUT RANGE = 3.75V TO 20V
)
)
R1
R2
The ground pin current can be found by examining the
Ground Pin Current curves in the Typical Performance
Characteristics. Power dissipation will be equal to the sum
of the two components listed above.
The LT1521 series regulators have internal thermal limit-
ing designed to protect the device during overload condi-
tions. For continuous normal load conditions the maxi-
mum junction temperature rating of 125
°
C must not be
exceeded. It is important to give careful consideration to
all sources of thermal resistance from junction to ambient.
Additional heat sources mounted nearby must also be
considered.
For surface mount devices, heat sinking is accomplished
by using the heat spreading capabilities of the PC board
and its copper traces. Copper board stiffeners and plated
through-holes can also be used to spread the heat gener-
ated by power devices.
The following tables list thermal resistance for each pack-
age. Measured values of thermal resistance for several
different board sizes and copper areas are listed for each
package. All measurements were taken in still air on
3/32" FR-4 board with one ounce copper. All NC leads were
connected to the ground plane.
Table 1. MS8 Package
COPPER AREA
TOPSIDE**
2500mm
2
1000mm
2
225mm
2
100mm
2
THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)
BACKSIDE
2500mm
2
2500mm
2
2500mm
2
2500mm
2
BOARD AREA
2500mm
2
2500mm
2
2500mm
2
2500mm
2
110
°
C/W
115
°
C/W
120
°
C/W
130
°
C/W
* Pin 4 is ground. ** Device is mounted on topside.
Table 2. S8 Package*
COPPER AREA
TOPSIDE** BACKSIDE
2500mm
2
1000mm
2
225mm
2
100mm
2
THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)
BOARD AREA
2500mm
2
2500mm
2
2500mm
2
2500mm
2
2500mm
2
2500mm
2
2500mm
2
2500mm
2
60
°
C/W
60
°
C/W
68
°
C/W
74
°
C/W
* Pins 3, 6, 7 are ground. ** Device is mounted on topside.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LT-1521-110-024 | 制造商:Carling Technologies 功能描述:LT-SERIES TOGGLE SWITCH - Bulk |
| LT-1521-111-006 | 制造商:Carling Technologies 功能描述:LT-SERIES TOGGLE SWITCH - Bulk |
| LT-1521-115-012 | 制造商:Carling Technologies 功能描述:LT-SERIES TOGGLE SWITCH - Bulk |
| LT-1521-151-012 | 制造商:Carling Technologies 功能描述:LT-SERIES TOGGLE SWITCH - Bulk |
| LT-1521-151-012/384-17131 | 制造商:Carling Technologies 功能描述:LT-SERIES TOGGLE SWITCH - Bulk |
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