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參數(shù)資料
| 型號： | L4949E |
| 廠商： | 意法半導(dǎo)體 |
| 元件分類： | 基準電壓源/電流源 |
| 英文描述： | Multifunction Very Low Drop Voltage Regulator(多功能低壓差電壓穩(wěn)壓器) |
| 中文描述： | 多功能非常低壓降穩(wěn)壓器（多功能低壓差電壓穩(wěn)壓器） |
| 文件頁數(shù)： | 5/10頁 |
| 文件大?。?/td> | 92K |
| 代理商： | L4949E |
With this structure very low dropout voltage at
currents up to 100mA is obtained. The dropout
operation of the standby regulator is maintained
down to 3V input supply voltage. The output volt-
age is regulated up to the transient input supply
voltage of 40V. With this feature no functional in-
terruptiondue to overvoltagepulses is generated.
The typical curve showing the standby output
voltage as a functionof theinput supply voltage is
shown in Fig. 2. The current consumption of the
device (quiescentcurrent) is less than 300
μ
A.
To reduce the quiescent current peak in the un-
dervoltage region and to improve the transient re-
sponse in this region, the dropout voltage is con-
trolled, the quiescent current as a function of the
supply input voltageis shown in Fig. 3.
Preregulator
To improve the transient immunity a preregulator
stabilized the internal supply voltage to 5V. This
internal voltage is present at Pin 3 (V
Z
). This volt-
age should not be used as an output because the
output capabilityis very small (
≤
10
μ
A).
This output may be used as an option when a
better transient behaviour for supply voltages less
than 8V is required(see alsoapplication note).
In this case a capacitor (100nF - 1
μ
F) must be
connectedbetween Pin 3 andGND. If thisfeature
is not used Pin 3 must be left open.
Reset Circuit
The block circuit diagram of the reset circuit is
shown in Fig. 4. The reset circuit supervises the
output voltage.
The reset thereshold of 4.5V is defined with the
internal reference voltage and standby output
drivider.
The reset pulse delay time t
RD
, is defined with the
chargetime of an externalcapacitor C
T
:
t
RD
=
C
T
2V
2
μ
A
The reaction time of the reset circuit originates
from the discharge time limitation of the reset ca-
pacitorC
T
and is proportionalto the value of C
T
.
The reaction time of thereset circuit increasesthe
noise immunity. Standby output voltage drops be-
low the reset threshold only a bit longer than the
reactiontime results in a shorterreset delay time.
The nominal reset delay time will be generated for
standby output voltage drops longer than approxi-
mately 50
μ
s.
The typical reset output waveforms are shown in
Fig. 5.
Sense Comparator
The sense comparator compares an input signal
with an internalvoltage reference of typical 1.23V.
The use of an external voltage divider makes this
comparatorvery flexible in the application.
It can be used to supervise the input voltage
either before or after the protection diode and to
give additional informations to the microprocessor
like low voltagewarnings.
Figure 3:
QuiescentCurrent vs. Supply Voltage
Figure 2:
OutputVoltage vs. Input Voltage
40V
L4949E
5/10
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| L4949ED | 功能描述:低壓差穩(wěn)壓器 - LDO 5V Multifunction 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 |
| L4949ED013TR | 功能描述:低壓差穩(wěn)壓器 - LDO 5V Multifunction 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 |
| L4949ED013TR-1LF | 制造商:STMicroelectronics 功能描述:REG LDO LIN FIX POS 5V 0.1A 8SOIC - Tape and Reel |
| L4949ED013TR-5 | 制造商:STMicroelectronics 功能描述:REG LDO LIN FIX POS 5V 0.1A 8SOIC NON ROHS - Tape and Reel |
| L4949ED013TR-VI | 制造商:STMicroelectronics 功能描述:REG LDO LIN FIX POS 5V 0.1A 8SOIC LEADED - Tape and Reel |
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