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參數(shù)資料
| 型號： | LM9074 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | Rheostat; Series:MP; Power Rating:300W; Resistance Max:200ohm; Terminal Type:Lugs; Resistance:200ohm; Type:Rheostat |
| 中文描述： | 系統(tǒng)電壓調(diào)節(jié)與保持活動開/關(guān) |
| 文件頁數(shù)： | 6/9頁 |
| 文件大小： | 193K |
| 代理商： | LM9074 |
Application Information
(Continued)
battery drops to less than 60 μA. With the possibility in many
applications for V
and the ON/OFF input pins to be con-
nected in a system through long lengths of wire, the ESD
protection of these pins has been increased to 12 kV with the
addition of small input bypass capacitors.
An output bypass capacitor of at least 0.1μF is required for
stability (47 μF is recommended). An input capacitor of 1 μF
or larger is recommended to improve line transient and noise
performance.
With the Keep-Alive input, a system microprocessor has the
ability to keep the regulator ON (with a logic “0” on
Keep-Alive) after the ON/OFF input has been commanded
OFF. A power-down sequence, when system variables are
typically stored in programmable memory, can be executed
and take as much time as necessary. At the end of the op-
eration the micro then pulls Keep-Alive high and the regula-
tor and system turn OFF and revert to the low quiescent cur-
rent standby mode.
For additional system reliability, consideration has been
made for the possibility of a short circuited load at the output
of the regulator. When the regulator is switched ON, conven-
tional current limiting and thermal shutdown protect the regu-
lator. When the regulator is switched OFF however, a
grounded V
supply to the micro (due to the shorted regu-
lator output) will force the Keep-Alive input to be low and
thus try to maintain the Keep-Alive mode of operation. With
a shorted load, the drain on the battery could be as high as
1.5A. A separate internal circuit monitors the output voltage
of the regulator. If V
OUT
is less than 4V, as would be the case
with a shorted load, the Keep-Alive function is logically dis-
abled to ensure that the regulator turns OFF and reverts to
less than a 60 μA load on the battery.
Conventional load dump protection is built in to withstand up
to +60V and 50V transients. A 1 k
resistor in series with
the ON/OFF and Keep-Alive inputs are recommended to
provide the same level of transient protection for these pins
if required. Protection against reverse polarity battery con-
nections is also built in. With a reversed battery the output of
the LM9074 will not go more negative than one diode drop
below ground. This will prevent damage to any of the 5V load
circuits.
For applications where the control logic is not required the
logic pins should be configured as shown in Figure 2 A
separate device, called the LM9071, can be used. The
LM9071 is available in a 5-lead TO-220 package and does
not provide control logic functions, but still retains all of the
protection features of the LM9074.
RESET FLAG
Excessive loading of the output to the point where the output
voltage drops by 300 mV to 500 mV will signal a reset flag to
the micro. This will warn of a V
supply that may produce
unpredictable operation of the system. On power-up and re-
covery from a fault condition the delay capacitor is used to
hold the micro in a reset condition for a programmable time
interval to allow the system operating voltages and
clock to stabilize before executing code. The typical delay
time interval can be estimated using the following equation:
DS101305-23
FIGURE 1. Typical Application Circuit
DS101305-24
FIGURE 2. Control Logic Not Used
L
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| LM9074EP | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Enhanced Plastic System Voltage Regulator with Keep-Alive ON/OFF Control |
| LM9074M | 功能描述:線性穩(wěn)壓器 - 標準 RoHS:否 制造商:STMicroelectronics 輸出類型: 極性: 輸出電壓:1.8 V 輸出電流:150 mA 負載調(diào)節(jié): 最大輸入電壓:5.5 V 線路調(diào)整率: 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:SOT-323-5L |
| LM9074M/NOPB | 功能描述:線性穩(wěn)壓器 - 標準 RoHS:否 制造商:STMicroelectronics 輸出類型: 極性: 輸出電壓:1.8 V 輸出電流:150 mA 負載調(diào)節(jié): 最大輸入電壓:5.5 V 線路調(diào)整率: 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:SOT-323-5L |
| LM9074MEP | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Enhanced Plastic System Voltage Regulator with Keep-Alive ON/OFF Control |
| LM9074MX | 功能描述:線性穩(wěn)壓器 - 標準 RoHS:否 制造商:STMicroelectronics 輸出類型: 極性: 輸出電壓:1.8 V 輸出電流:150 mA 負載調(diào)節(jié): 最大輸入電壓:5.5 V 線路調(diào)整率: 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:SOT-323-5L |
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