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參數(shù)資料
| 型號： | LMV761MA |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 比較器 |
| 英文描述： | Low Voltage, Precision Comparator with Push-Pull Output |
| 中文描述： | COMPARATOR, 1000 uV OFFSET-MAX, 225 ns RESPONSE TIME, PDSO8 |
| 封裝： | SOIC-8 |
| 文件頁數(shù)： | 8/10頁 |
| 文件大?。?/td> | 346K |
| 代理商： | LMV761MA |
Application Hints
Basic Comparator
A basic comparator circuit is used to convert analog input
signals to digital output signals. The comparator compares
an input voltage (V
IN
) at the non-inverting input to the refer-
ence voltage (V
REF
) at the inverting pin. If V
IN
is less than
V
REF
the output (V
O
) is low (V
OL
). However, if V
IN
is greater
than V
REF
, the output voltage (V
O
) is high (V
OH
).
Hysteresis
The basic comparator configuration may oscillate or produce
a noisy output if the applied differential input is near the
comparator’s input offset voltage. This tends to occur when
the voltage on one input is equal or very close to the other
input voltage. Adding hysteresis can prevent this problem.
Hysteresis creates two switching thresholds (one for the
rising input voltage and the other for the falling input volt-
age). Hysteresis is the voltage difference between the two
switching thresholds. When both inputs are nearly equal,
hysteresis causes one input to effectively move quickly past
the other. Thus, moving the input out of the region in which
oscillation may occur.
Hysteresis can easily be added to a comparator in a non-
inverting configuration with two resistors and positive feed-
back
Figure 2
. The output will switch from low to high when
V
IN
rises up to V
IN1
, where V
IN1
is calculated by
V
IN1
= (V
REF
(R
1
+R
2
))/R
2
The output will switch from high to low when V
IN
falls to V
IN2
,
where V
IN2
is calculated by
V
IN2
= (V
REF
(R
1
+R
2
) – V
CC
R
1
)/R
2
The Hysteresis is the difference between V
IN1
and V
IN2
.
V
IN
= V
IN1
- V
= ((V
REF
(R
1
+R
2
))/R
2
)-((V
REF
(R
1
+R
2
)) - (V
CC
R
1
))/R
2
)
= V
CC
R
1
/R
2
Input
The LMV761/762 have near zero input bias current. This
allows very high resistance circuits to be used without any
concern for matching input resistances. This also allows the
use of very small capacitors in R-C type timing circuits. This
reduces the cost of the capacitors and amount of board
space used.
Shutdown Mode
The LMV761 features a low-power shutdown pin that is
activated by driving SD low. In shutdown mode, the output is
in a high impedance state, supply current is reduced to 20nA
and the comparator is disabled. Driving SD high will turn the
comparator on. The SD pin should not be left unconnected
due to the fact that it is a high impedance input. When left
unconnected, the output will be at an unknown voltage. Also
do not three-state the SD pin.
The maximum input voltage for SD is 5.5V, referred to
ground and is not limited by V
. This allows the use of 5V
logic to drive SD while V
operates at a lower voltage, such
as 3V. The logic threshold limits for SD are proportional to
V
CC
.
Board Layout and Bypassing
The LMV761/762 is designed to be stable and oscillation
free, but it is still important to include the proper bypass
capacitors and ground pickups. Ceramic 0.1μF capacitors
should be placed at both supplies to provide clean switching.
Minimize the length of signal traces to reduce stray capaci-
tance.
20037028
20037031
FIGURE 1. Basic Comparator
20037026
20037027
FIGURE 2. Non-Inverting Comparator Configuration
L
www.national.com
8
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LMV761MA | 制造商:Texas Instruments 功能描述:IC COMPARATOR SMD SOIC8 761 |
| LMV761MA/NOPB | 功能描述:校驗器 IC Low Vltg,Prec Comp RoHS:否 制造商:STMicroelectronics 產(chǎn)品: 比較器類型: 通道數(shù)量: 輸出類型:Push-Pull 電源電壓-最大:5.5 V 電源電壓-最小:1.1 V 補償電壓（最大值）:6 mV 電源電流（最大值）:1350 nA 響應(yīng)時間: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SC-70-5 封裝:Reel |
| LMV761MAX | 功能描述:校驗器 IC RoHS:否 制造商:STMicroelectronics 產(chǎn)品: 比較器類型: 通道數(shù)量: 輸出類型:Push-Pull 電源電壓-最大:5.5 V 電源電壓-最小:1.1 V 補償電壓（最大值）:6 mV 電源電流（最大值）:1350 nA 響應(yīng)時間: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SC-70-5 封裝:Reel |
| LMV761MAX/NOPB | 功能描述:校驗器 IC RoHS:否 制造商:STMicroelectronics 產(chǎn)品: 比較器類型: 通道數(shù)量: 輸出類型:Push-Pull 電源電壓-最大:5.5 V 電源電壓-最小:1.1 V 補償電壓（最大值）:6 mV 電源電流（最大值）:1350 nA 響應(yīng)時間: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SC-70-5 封裝:Reel |
| LMV761MF | 功能描述:校驗器 IC RoHS:否 制造商:STMicroelectronics 產(chǎn)品: 比較器類型: 通道數(shù)量: 輸出類型:Push-Pull 電源電壓-最大:5.5 V 電源電壓-最小:1.1 V 補償電壓（最大值）:6 mV 電源電流（最大值）:1350 nA 響應(yīng)時間: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SC-70-5 封裝:Reel |
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