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參數(shù)資料
| 型號(hào)： | LMC6042AIM |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 運(yùn)動(dòng)控制電子 |
| 英文描述： | CMOS Dual Micropower Operational Amplifier |
| 中文描述： | DUAL OP-AMP, 3000 uV OFFSET-MAX, 0.1 MHz BAND WIDTH, PDSO8 |
| 封裝： | SOIC-8 |
| 文件頁數(shù)： | 7/13頁 |
| 文件大?。?/td> | 401K |
| 代理商： | LMC6042AIM |
Typical Performance Characteristics
V
S
=
±
7.5V, T
A
= 25C unless otherwise specified (Continued)
Applications Hints
AMPLIFIER TOPOLOGY
The LMC6042 incorporates a novel op-amp design topology
that enables it to maintain rail-to-rail output swing even when
driving a large load. Instead of relying on a push-pull unity
gain output buffer stage, the output stage is taken directly
from the internal integrator, which provides both low output
impedance and large gain. Special feed-forward compensa-
tion design techniques are incorporated to maintain stability
over a wider range of operating conditions than traditional
micropower op-amps. These features make the LMC6042
both easier to design with, and provide higher speed than
products typically found in this ultra-low power class.
COMPENSATING FOR INPUT CAPACITANCE
It is quite common to use large values of feedback resis-
tance with amplifiers with ultra-low input curent, like the
LMC6042.
Although the LMC6042 is highly stable over a wide range of
operating conditions, certain precautions must be met to
achieve the desired pulse response when a large feedback
resistor is used. Large feedback resistors and even small
values of input capacitance, due to transducers, photo-
diodes, and circuit board parasitics, reduce phase margins.
When high input impedances are demanded, guarding of the
LMC6042 is suggested. Guarding input lines will not only re-
duce leakage, but lowers stray input capacitance as well.
(See
Printed-Circuit-Board Layout for High Impedance
Work).
The effect of input capacitance can be compensated for by
adding a capacitor. Place a capacitor, C
f
, around the feed-
back resistor (as in Figure 1 ) such that:
or
R1 C
IN
≤
R2 C
f
Since it is often difficult to know the exact value of C
, C
can
be experimentally adjusted so that the desired pulse re-
sponse is achieved. Refer to the LMC660 and the LMC662
for a more detailed discussion on compensating for input ca-
pacitance.
CAPACITIVE LOAD TOLERANCE
Direct capacitive loading will reduce the phase margin of
many op-amps. A pole in the feedback loop is created by the
combination of the op-amp’s output impedance and the ca-
pacitive load. This pole induces phase lag at the unity-gain
crossover frequency of the amplifier resulting in either an os-
cillatory or underdamped pulse response. With a few exter-
nal components, op amps can easily indirectly drive capaci-
tive loads, as shown in Figure 2
In the circuit of Figure 2 R1 and C1 serve to counteract the
loss of phase margin by feeding the high frequency compo-
Stability vs Capacitive Load
DS011137-43
Stability vs Capacitive Load
DS011137-44
DS011137-5
FIGURE 1. Cancelling the Effect of Input Capacitance
DS011137-6
FIGURE 2. LMC6042 Noninverting Gain of 10 Amplifier,
Compensated to Handle Capacitive Loads
www.national.com
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相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LMC6042AIN | CMOS Dual Micropower Operational Amplifier |
| LMC6042IM | CMOS Dual Micropower Operational Amplifier |
| LMC6042IN | CMOS Dual Micropower Operational Amplifier |
| LMC6044 | CMOS Quad Micropower Operational Amplifier |
| LMC6044AIM | CMOS Quad Micropower Operational Amplifier |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LMC6042AIM | 制造商:Texas Instruments 功能描述:OP AMP DUAL MICROPOWER POWERWISE |
| LMC6042AIM/NOPB | 功能描述:運(yùn)算放大器 - 運(yùn)放 MicroPwr CMOS Op Amp RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補(bǔ)償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| LMC6042AIMX | 功能描述:運(yùn)算放大器 - 運(yùn)放 RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補(bǔ)償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| LMC6042AIMX/NOPB | 功能描述:運(yùn)算放大器 - 運(yùn)放 RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補(bǔ)償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| LMC6042AIN | 功能描述:運(yùn)算放大器 - 運(yùn)放 RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補(bǔ)償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
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