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參數(shù)資料
| 型號(hào)： | LMV796 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | 17 MHz, Low Noise, CMOS Input, 1.8V Operational Amplifiers |
| 中文描述： | 17兆赫，低噪聲，CMOS輸入，1.8V的運(yùn)算放大器 |
| 文件頁數(shù)： | 13/19頁 |
| 文件大?。?/td> | 1152K |
| 代理商： | LMV796 |
Application Information
ADVANTAGES OF THE LMV796/LMV797
Wide Bandwidth at Low Supply Current
The LMV796 and LMV797 are high performance op amps
that provide a unity gain bandwidth of 17 MHz while drawing
a low supply current of 1.15 mA. This makes them ideal for
providing wideband amplification in portable applications.
Low Input Referred Noise and Low Input Bias Current
The LMV796/LMV797 have a very low input referred voltage
noise density (5.8 nV/
at 1 kHz). A CMOS input stage
ensures a small input bias current (100 fA) and low input
referred current noise (0.01 pA/
maintaining signal fidelity, and makes the LMV796 and
LMV797 ideal for audio and sensor based applications.
). This is very helpful in
Low Supply Voltage
The LMV796 and the LMV797 have performance guaran-
teed at 2.5V and 5V supply. The LMV796 family is guaran-
teed to be operational at all supply voltages between 2.0V
and 5.5V, for ambient temperatures ranging from 40C to
125C, thus utilizing the entire battery lifetime. The LMV796
and LMV797 are also guaranteed to be operational at 1.8V
supply voltage, for temperatures between 0C and 125C.
This makes the LMV796 family ideal for usage in low-voltage
commercial applications.
RRO and Ground Sensing
Rail-to-rail output swing provides maximum possible dy-
namic range at the output. This is particularly important
when operating at low supply voltages. An innovative posi-
tive feedback scheme is used to boost the current drive
capability of the output stage. This allows the LMV796 and
the LMV797 to source more than 40 mA of current at 1.8V
supply. This also limits the performance of the LMV796
family as comparators, and hence the usage of the LMV796
and the LMV797 in an open-loop configuration is not recom-
mended. The input common-mode range includes the nega-
tive supply rail which allows direct sensing at ground in
single supply operation.
Small Size
The small footprint of the LMV796 and the LMV797 package
saves space on printed circuit boards, and enables the
design of smaller electronic products, such as cellular
phones, pagers, or other portable systems. Long traces
between the signal source and the op amp make the signal
path susceptible to noise. By using the physically smaller
LMV796 or LMV797 package, the op amp can be placed
closer to the signal source, reducing noise pickup and in-
creasing signal integrity.
CAPACITIVE LOAD TOLERANCE
The LMV796 and LMV797 can directly drive 120 pF in
unity-gain without oscillation. The unity-gain follower is the
most sensitive configuration to capacitive loading. Direct
capacitive loading reduces the phase margin of amplifiers.
The combination of the amplifier’s output impedance and the
capacitive load induces phase lag. This results in either an
underdamped pulse response or oscillation. To drive a
heavier capacitive load, the circuit in
Figure 1
can be used.
In
Figure 1
, the isolation resistor R
and the load capacitor
C
form a pole to increase stability by adding more phase
margin to the overall system. The desired performance de-
pends on the value of R
ISO
. The bigger the R
ISO
resistor
value, the more stable V
will be. Increased R
would,
however, result in a reduced output swing and short circuit
current.
INPUT CAPACITANCE AND FEEDBACK CIRCUIT
ELEMENTS
The LMV796 family has a very low input bias current (100 fA)
and a low 1/f noise corner frequency (400 Hz), which makes
it ideal for sensor applications. However, to obtain this per-
formance a large CMOS input stage is used, which adds to
the input capacitance of the op amp, C
. Though this does
not affect the DC and low frequency performance, at higher
frequencies the input capacitance interacts with the input
and the feedback impedances to create a pole, which results
in lower phase margin and gain peaking. This can be con-
trolled by being selective in the use of feedback resistors, as
well as, by using a feedback capacitance, C
. For example,
in the inverting amplifier shown in
Figure 2
, if C
and C
are
ignored and the open loop gain of the op amp is considered
infinite then the gain of the circuit is R
/R
. An op amp,
however, usually has a dominant pole, which causes its gain
to drop with frequency. Hence, this gain is only valid for DC
and low frequency. To understand the effect of the input
capacitance coupled with the non-ideal gain of the op amp,
the circuit needs to be analyzed in the frequency domain
using a Laplace transform.
20183561
FIGURE 1. Isolation of C
L
to Improve Stability
20183564
FIGURE 2. Inverting Amplifier
L
www.national.com
13
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LMV796MF | 17 MHz, Low Noise, CMOS Input, 1.8V Operational Amplifiers |
| LMV796MFX | 17 MHz, Low Noise, CMOS Input, 1.8V Operational Amplifiers |
| LMV797 | 17 MHz, Low Noise, CMOS Input, 1.8V Operational Amplifiers |
| LMV797MM | 17 MHz, Low Noise, CMOS Input, 1.8V Operational Amplifiers |
| LMV797MMX | 17 MHz, Low Noise, CMOS Input, 1.8V Operational Amplifiers |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LMV796MF | 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 |
| LMV796MF/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 |
| LMV796MFX | 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 |
| LMV796MFX/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 |
| LMV796QMF/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 |
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