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參數(shù)資料
| 型號(hào)： | LM1946 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | LM1946 Over/Under Current Limit Diagnostic Circuit |
| 中文描述： | LM1946超過(guò)/診斷下電流限制電路 |
| 文件頁(yè)數(shù)： | 9/12頁(yè) |
| 文件大?。?/td> | 216K |
| 代理商： | LM1946 |
Application Hints
(Continued)
TL/H/8707–13
FIGURE 12. Comparator Input Stage
THE OUTPUT SECTION
The output section of the LM1946 is different from most
automotive comparators as it employs high beta proprietary
PNP transistors which are very rugged and capable of high-
er output currents. Each of the five comparator outputs is
capable of at least 20 mA of drive and are internally current
limited and protected against supply overvoltage. The
LM1946 is therefore capable of driving LED’s directly and
larger bulbs via an external grounded base NPN (see Fig-
ures 13 and 14). The outputs can also be wired-or together
without harm.
For use in systems with a microprocessor flag instead of a
dashboard indicator, the LM1946 can be powered by a stan-
dard 5V logic supply. This prevents the LM1946 output from
swinging above the microprocessor supply which might
cause latch problems. Since the input common mode range
is independent of supply, the inputs can still operate at any
level up to 26V. Since the outputs can source current only,
pull-down resistors as in Figure 15 are required, their value
depending on the input drive requirements of the particular
microprocessor used. When operating with a V
CC
supply
less than 7V, it is important to connect the V
REF
pin to V
CC
.
This forces V
REF
to a fixed voltage which is used for bias of
internal circuitry.
TL/H/8707–19
FIGURE 13
TL/H/8707–14
FIGURE 14
TEST PIN
The test pin is a high impedance logic input. Forcing this pin
high (
t
2V) forces all five comparator outputs on. This is
used to test the indicator LED display (or other output load).
The usual application circuit connects this pin to the ignition
crank line. During engine crank, therefore, the LM1946 out-
put display will light, similar to the usual dashboard indica-
tors. The test pin was designed to operate with the usual
transient voltages found on the crank line as long as a limit-
ing resistor (e.g. 30k) separates them (Figure 1).
Minimum pulse width (ms)
&
0.01
a
1.5
#
C1 (
m
F)
TL/H/8707–15
FIGURE 15
9
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PDF描述 |
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| LM1946M | LM1946 Over/Under Current Limit Diagnostic Circuit |
| LM1946N | LM1946 Over/Under Current Limit Diagnostic Circuit |
| LM194 | LM194/LM394 Supermatch Pair |
| LM1950 | 750 mA High Side Switch |
| LM1950T | 750 mA High Side Switch |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM1946M | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:LM1946 Over/Under Current Limit Diagnostic Circuit |
| LM1946N | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:LM1946 Over/Under Current Limit Diagnostic Circuit |
| LM1949 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:LM1949 Injector Drive Controller |
| LM1949M | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:LM1949 Injector Drive Controller |
| LM1949N | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
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