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參數(shù)資料
| 型號(hào)： | FAN2519 |
| 廠商： | Fairchild Semiconductor Corporation |
| 英文描述： | 50 mA CMOS LDO Regulators with Fast Start Enable |
| 中文描述： | 50毫安的CMOS LDO穩(wěn)壓器的快速啟動(dòng)功能 |
| 文件頁(yè)數(shù)： | 3/10頁(yè) |
| 文件大?。?/td> | 246K |
| 代理商： | FAN2519 |
FAN2518/FAN2519
PRODUCT SPECIFICATION
REV. 1.0.6 2/14/03
3
An Enable pin, available on all devices, allows the user to
shut down the regulator output to conserve power, reducing
supply current to less than 1μA. The output can then be
re-Enabled within 500μSec, fulfilling the fast power-cycling
needs of CDMA applications. Depending on the model
selected, other control and status functions are available at
pin 4 to enhance the operation of the device. The adjustable-
voltage versions utilize pin 4 to connect to an external
voltage divider which feeds back to the regulator error
amplifier, thereby setting the voltage as desired. Two other
functions are available in the fixed-voltage versions: in
noise-sensitive applications, an external Bypass capacitor
connection is provided that allows the user to achieve opti-
mal noise performance at the output, while the Error output
functions as a diagnostic flag to indicate that the output
voltage has dropped more than 5% below the nominal fixed
voltage.
Applications Information
External Capacitors – Selection
The FAN2518/19 allows the user to utilize a wide variety of
capacitors compared to other LDO products. An innovative
design approach offers significantly reduced sensitivity to
ESR (Effective Series Resistance), which degrades regulator
loop stability in older designs. While the improvements fea-
tured in the FAN2518/19 family greatly simplify the design
task, capacitor quality still must be considered if the designer
is to achieve optimal circuit performance. In general,
ceramic capacitors offer superior ESR performance, at a
lower cost and a smaller case size than tantalums. Those with
X7R or Y5Vdielectric offer the best temperature coefficient
characteristics. The combination of tolerance and variation
over temperature in some capacitor types can result in signif-
icant variations, resulting in unstable performance over rated
conditions.
Input Capacitor
An input capacitor of 2.2μF (nominal value) or greater,
connected between the Input pin and Ground, located in
close proximity to the device, will improve transient
response and noise rejection. Higher values will offer supe-
rior input ripple rejection and transient response. An input
capacitor is recommended when the input source, either a
battery or a regulated AC voltage, is located far from the
device. Any good quality ceramic, tantalum, or metal film
capacitor will give acceptable performance, however tanta-
lum capacitors with a surge current rating appropriate to the
application must be selected to avoid catastrophic failure.
Output Capacitor
An output capacitor is required to maintain regulator loop
stability. Unlike many other LDO regulators, the FAN2518/19
family of products are nearly insensitive to output capacitor
ESR. Stable operation will be achieved with a wide variety
of capacitors with ESR values ranging from 10m
to 10
or
more. Tantalum or aluminum electrolytic, or multilayer
ceramic types can all be used. A nominal value of at least
1μF is recommended.
Bypass Capacitor (FAN2518 Only)
In the fixed-voltage configuration, connecting a capacitor
between the bypass pin and ground can significantly reduce
noise on the output. Values ranging from 470pF to 10nF can
be used, depending on the sensitivity to output noise in the
application.
At the high-impedance Bypass pin, care must be taken in the
circuit layout to minimize noise pickup, and capacitors must
be selected to minimize current loading (leakage). Noise
pickup from external sources can be considerable. Leakage
currents into the Bypass pin will directly affect regulator
accuracy and should be kept as low as possible; thus, high-
quality ceramic and film types are recommended for their
low leakage characteristics. Cost-sensitive applications not
concerned with noise can omit this capacitor.
Control Functions
Enable Pin
Applying a voltage of 0.4V or less at the Enable pin will dis-
able the output, reducing the quiescent output current to less
than 1μA, while a voltage of 2.0V or greater will enable the
device. If this shutdown function is not needed, the pin can
simply be connected to the V
IN
will cause erratic operation.
pin. Allowing this pin to float
Error Flag (FAN2519 Only)
To indicate conditions such as input voltage dropout
(low V
IN
), overheating, or overloading (excessive output
current), the ERR pin indicates a fault condition. It is an
open-drain output which is HIGH when the voltage at V
is greater than 95% of the nominal rated output voltage and
LOW when V
OUT
is less than 95% or the rated output volt-
age, as specified in the error trip level characteristics.
OUT
A logic pullup resistor of 100K
output. The pin can be left disconnected if unused.
is recommended at this
Thermal Protection
The FAN2518/19 is designed to supply high peak output
currents of up to 1A for brief periods, however this output
load will cause the device temperature to increase and
exceed maximum ratings due to power dissipation. During
output overload conditions, when the die temperature
exceeds the shutdown limit temperature of 150°C, onboard
thermal protection will disable the output until the tempera-
ture drops below this limit, at which point the output is
then re-enabled. During a thermal shutdown situation the
user may assert the power-down function at the Enable
pin, reducing power consumption to the minimum level
I
GND
· V
IN
.
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| FAN2519285 | 制造商:未知廠家 制造商全稱(chēng):未知廠家 功能描述:Positive Fixed Voltage Regulator |
| FAN2519S25 | 制造商:未知廠家 制造商全稱(chēng):未知廠家 功能描述:Positive Fixed Voltage Regulator |
| FAN2519S25X | 功能描述:低壓差穩(wěn)壓器 - LDO LDO Voltage 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(dòng)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(lèi)型:Fixed 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| FAN2519S25X_Q | 功能描述:低壓差穩(wěn)壓器 - LDO LDO Voltage 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(dòng)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(lèi)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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