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參數(shù)資料
| 型號(hào)： | LM2984CT |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類(lèi)： | 電源管理 |
| 英文描述： | LM2984C Microprocessor Power Supply System |
| 中文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PZFM11 |
| 封裝： | POWER, PLASTIC, TO-220, 11 PIN |
| 文件頁(yè)數(shù)： | 11/14頁(yè) |
| 文件大?。?/td> | 284K |
| 代理商： | LM2984CT |
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Typical Performance Characteristics
(Continued)
Output Voltage
TL/H/8821–8
Device Dissipation vs
Ambient Temperature
TL/H/8821–9
Output Capacitor ESR
(Standby Output, Pin 9)
TL/H/8821–13
Output Capacitor ESR
(Buffer Output, Pin 10)
TL/H/8821–14
Output Capacitor ESR
(Main Output, Pin 11)
TL/H/8821–15
Application Hints
OUTPUT CAPACITORS
The LM2984C output capacitors are required for stability.
Without them, the regulator outputs will oscillate, sometimes
by many volts. Though the 10
m
F shown are the minimum
recommended values, actual size and type may vary de-
pending upon the application load and temperature range.
Capacitor effective series resistance (ESR) also affects the
IC stability. Since ESR varies from one brand to the next,
some bench work may be required to determine the mini-
mum capacitor value to use in production. Worst case is
usually determined at the minimum ambient temperature
and the maximum load expected.
Output capacitors can be increased in size to any desired
value above the minimum. One possible purpose of this
would be to maintain the output voltages during brief condi-
tions of negative input transients that might be characteris-
tic of a particular system.
Capacitors must also be rated at all ambient temperatures
expected in the system. Many aluminum type electrolytics
will freeze at temperatures less than
b
30
§
C, reducing their
effective capacitance to zero. To maintain regulator stability
down to
b
40
§
C, capacitors rated at that temperature (such
as tantalums) must be used.
Each output
must
be terminated by a capacitor, even if it is
not used.
STANDBY OUTPUT
The standby output is intended for use in systems requiring
standby memory circuits. While the high current regulator
outputs are controlled with the ON/OFF pin described later,
the standby output remains on under all conditions as long
as sufficient input voltage is supplied to the IC. Thus, memo-
ry and other circuits powered by this output remain unaffect-
ed by positive line transients, thermal shutdown, etc.
The standby regulator circuit is designed so that the quies-
cent current to the IC is very low (
k
1.5 mA) when the other
regulator outputs are off.
The capacitor on the output of this regulator can be in-
creased without bound. This will help maintain the output
voltage during negative input transients and will also help to
reduce the noise on all three outputs. Because the other
two track the standby output: therefore any noise reduction
here will also reduce the other two noise voltages.
BUFFER OUTPUT
The buffer output is designed to drive peripheral sensor cir-
cuitry in a
m
P system. It will track the standby and main
regulator within a few millivolts in normal operation. There-
fore, a peripheral sensor can be powered off this supply and
have the same operating voltage as the
m
P system. This is
important if a ratiometric sensor system is being used.
The buffer output can be short circuited while the other two
outputs are in normal operation. This protects the
m
P sys-
tem from disruption of power when a sensor wire, etc. is
temporarily shorted to ground, i.e. only the sensor signal
would be interrupted, while the
m
P and memory circuits
would remain operational.
The buffer output is similar to the main output in that it is
controlled by the ON/OFF switch in order to save power in
11
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM2984CT/NOPB | 功能描述:低壓差穩(wěn)壓器 - 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(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 |
| LM2984T | 功能描述:低壓差穩(wěn)壓器 - 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(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 |
| LM2984T/NOPB | 功能描述:低壓差穩(wěn)壓器 - 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(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 |
| LM2990J-12-QML | 制造商:National Semiconductor Corporation 功能描述:LDO Regulator Neg -12V 1.8A 16-Pin CDIP Tray 制造商:National Semiconductor 功能描述:LDO Regulator Neg -12V 1.8A 16-Pin CDIP Tray |
| LM2990J-15-QML | 制造商:Texas Instruments 功能描述:LDO Regulator Neg -15V 1.8A 16-Pin CDIP Tray |
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