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參數(shù)資料
| 型號(hào)： | NCV4276A |
| 廠商： | ON SEMICONDUCTOR |
| 英文描述： | 400 mA Low-Drop Voltage Regulator(400mA低壓降穩(wěn)壓器) |
| 中文描述： | 400毫安低壓降穩(wěn)壓器（400mA的低壓降穩(wěn)壓器） |
| 文件頁數(shù)： | 14/23頁 |
| 文件大?。?/td> | 199K |
| 代理商： | NCV4276A |
NCV4276, NCV4276A
http://onsemi.com
14
Circuit Description
The NCV4276 is an integrated low dropout regulator that
provides a regulated voltage at 400 mA to the output. It is
enabled with an input to the inhibit pin. The regulator
voltage is provided by a PNP pass transistor controlled by
an error amplifier with a bandgap reference, which gives it
the lowest possible dropout voltage. The output current
capability is 400 mA, and the base drive quiescent current
is controlled to prevent oversaturation when the input
voltage is low or when the output is overloaded. The
regulator is protected by both current limit and thermal
shutdown. Thermal shutdown occurs above 150
°
C to
protect the IC during overloads and extreme ambient
temperatures.
Regulator
The error amplifier compares the reference voltage to a
sample of the output voltage (V
Q
) and drives the base of a
PNP series pass transistor via a buffer. The reference is a
bandgap design to give it a temperature
stable output.
Saturation control of the PNP is a function of the load
current and input voltage. Oversaturation of the output
power device is prevented, and quiescent current in the
ground pin is minimized. See Figure 5, Test Circuit, for
circuit element nomenclature illustration.
Regulator Stability Considerations
The input capacitors (C
I1
and C
I2
) are necessary to
stabilize the input impedance to avoid voltage line
influences. Using a resistor of approximately 1.0
series with C
I2
can stop potential oscillations caused by
stray inductance and capacitance.
The output capacitor helps determine three main
characteristics of a linear regulator: startup delay, load
transient response and loop stability. The capacitor value
and type should be based on cost, availability, size and
temperature constraints. The aluminum electrolytic
capacitor is the least expensive solution, but, if the circuit
operates at low temperatures (
25
°
C to
40
°
C), both the
value and ESR of the capacitor will vary considerably. The
capacitor manufacturer’s data sheet usually provides this
information.
in
The value for the output capacitor C
Q
, shown in Figure 3,
should work for most applications; however, it is not
necessarily the optimized solution. Stability is guaranteed
for C
Q
22 F and an ESR
Adjustable regulator and C
Q
for the 1.8 V, 2.5 V, and 3.3 V regulators. See Figures 5 and
6 for output stability at various load and capacitive ESR
conditions.
2.5 for the 5.0 V and
10 F and an ESR
1.8
Inhibit Input
The inhibit pin is used to turn the regulator on or off. By
holding the pin down to a voltage less than 0.5 V, the output
of the regulator will be turned off. When the voltage on the
Inhibit pin is greater than 3.5 V, the output of the regulator
will be enabled to power its output to the regulated output
voltage. The inhibit pin may be connected directly to the
input pin to give constant enable to the output regulator.
Setting the Output Voltage (Adjustable Version)
The output voltage range of the adjustable version can be
set between 2.5 V and 20 V (Figure ). This is accomplished
with an external resistor divider feeding back the voltage
to the IC back to the error amplifier by the voltage adjust
pin VA. The internal reference voltage is set to a
temperature stable reference of 2.5 V.
The output voltage is calculated from the following
formula. Ignoring the bias current into the VA pin:
VQ
[(R1
R2) * Vref] R2
Use R2 < 50 k to avoid significant voltage output errors
due to VA bias current.
Connecting VA directly to Q without R1 and R2 creates
an output voltage of 2.5 V.
Designers should consider the tolerance of R1 and R2
during the design phase.
The input voltage range for operation (pin 1) of the
adjustable version is between (V
Q
+ 0.5 V) and 40 V.
Internal bias requirements dictate a minimum input voltage
of 4.5 V. The dropout voltage for output voltages less than
4.0 V is (4.5 V
V
Q
).
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| NCV4949 | 100 mA, 5.0 V, Low Dropout Voltage Regulator with Power-On Reset(100 mA, 5.0 V, 具有上電復(fù)位功能的低壓差穩(wěn)壓器) |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| NCV4276ADS50G | 功能描述:低壓差穩(wěn)壓器 - LDO ANA LDO REG 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: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| NCV4276ADS50R4G | 功能描述:低壓差穩(wěn)壓器 - LDO ANA LDO REG 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: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| NCV4276ADSADJG | 功能描述:低壓差穩(wěn)壓器 - LDO ANA LDO REG 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: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| NCV4276ADSADJG | 制造商:ON Semiconductor 功能描述:Linear Voltage Regulator IC |
| NCV4276ADSADJR4G | 功能描述:低壓差穩(wěn)壓器 - LDO ANA LDO REG 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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