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參數(shù)資料
| 型號： | LT1963-3.3 |
| 廠商： | Linear Technology Corporation |
| 英文描述： | 1.5A, Low Noise, Fast Transient Response LDO Regulators(3.3V輸出,1.5A,低噪聲,快速瞬變響應,低壓差輸出穩(wěn)壓器) |
| 中文描述： | 1.5A的，低噪聲，快速瞬態(tài)響應LDO穩(wěn)壓器（3.3V輸出，1.5A的，低噪聲，快速瞬變響應，低壓差輸出穩(wěn)壓器） |
| 文件頁數(shù)： | 10/16頁 |
| 文件大?。?/td> | 222K |
| 代理商： | LT1963-3.3 |
10
LT1963 Series
Figure 2. Adjustable Operation
IN
1963 F02
R2
OUT
V
IN
V
OUT
ADJ
GND
LT1963
R1
+
V
V
R
R
I
R
V
I
ADJ
OUTPUT RANGE = 1.21V TO 20V
V
A
OUT
ADJ
ADJ
=
+
(
1
)( )
=
=
1 21
.
1
2
2
1 21
3
μ
AT 25 C
.
Figure 3. Ceramic Capacitor DC Bias Characteristics
APPLICATIU
The LT1963 series are 1.5A low dropout regulators opti-
mized for fast transient response. The devices are capable
of supplying 1.5A at a dropout voltage of 350mV. The low
operating quiescent current (1mA) drops to less than 1
μ
A
in shutdown. In addition to the low quiescent current, the
LT1963 regulators incorporate several protection features
which make them ideal for use in battery-powered sys-
tems. The devices are protected against both reverse input
and reverse output voltages. In battery backup applica-
tions where the output can be held up by a backup battery
when the input is pulled to ground, the LT1963-X acts like
it has a diode in series with its output and prevents reverse
current flow. Additionally, in dual supply applications
where the regulator load is returned to a negative supply,
the output can be pulled below ground by as much as 20V
and still allow the device to start and operate.
W
U
U
DC BIAS VOLTAGE (V)
C
1963 F03
20
0
–20
–40
–60
–80
–1000
4
8
10
2
6
12
14
X5R
Y5V
16
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10
μ
F
Adjustable Operation
The adjustable version of the LT1963 has an output
voltage range of 1.21V to 20V. The output voltage is set by
the ratio of two external resistors as shown in Figure 2. The
device servos the output to maintain the voltage at the ADJ
pin at 1.21V referenced to ground. The current in R1 is
then equal to 1.21V/R1 and the current in R2 is the current
in R1 plus the ADJ pin bias current. The ADJ pin bias
current, 3
μ
A at 25
°
C, flows through R2 into the ADJ pin.
The output voltage can be calculated using the formula in
Figure 2. The value of R1 should be less than 4.17k to
minimize errors in the output voltage caused by the ADJ
pin bias current. Note that in shutdown the output is turned
off and the divider current will be zero.
The adjustable device is tested and specified with the ADJ
pin tied to the OUT pin for an output voltage of 1.21V.
Specifications for output voltages greater than 1.21V will
be proportional to the ratio of the desired output voltage to
1.21V: V
OUT
/1.21V. For example, load regulation for an
output current change of 1mA to 1.5A is –3mV typical at
V
OUT
= 1.21V. At V
OUT
= 5V, load regulation is:
(5V/1.21V)(–3mV) = –12.4mV
Output Capacitance and Transient Response
The LT1963 regulators are designed to be stable with a
wide range of output capacitors. The ESR of the output
capacitor affects stability, most notably with small capaci-
tors. A minimum output capacitor of 10
μ
F with an ESR of
3
or less is recommended to prevent oscillations. Larger
values of output capacitance can decrease the peak devia-
tions and provide improved transient response for larger
load current changes. Bypass capacitors, used to decouple
individual components powered by the LT1963, will in-
crease the effective output capacitor value.
Extra consideration must be given to the use of ceramic
capacitors. Ceramic capacitors are manufactured with a
variety of dielectrics, each with different behavior over
temperature and applied voltage. The most common
dielectrics used are Z5U, Y5V, X5R and X7R. The Z5U and
Y5V dielectrics are good for providing high capacitances
in a small package, but exhibit strong voltage and tem-
perature coefficients as shown in Figures 3 and 4. When
used with a 5V regulator, a 10
μ
F Y5V capacitor can exhibit
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相關代理商/技術參數(shù) |
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|---|---|
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| LT1963A-1.5 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:1.5A, Low Noise, Fast Transient Response LDO Regulators |
| LT1963A-1.8 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:1.5A, Low Noise, Fast Transient Response LDO Regulators |
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