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參數(shù)資料
| 型號： | MAX4209 |
| 廠商： | Maxim Integrated Products, Inc. |
| 元件分類： | 運動控制電子 |
| 英文描述： | Ultra-Low Offset/Drift, Precision Instrumentation Amplifiers with REF Buffer |
| 中文描述： | 超低失調(diào)/漂移、高精度儀表放大器，提供REF緩沖器 |
| 文件頁數(shù)： | 13/17頁 |
| 文件大?。?/td> | 263K |
| 代理商： | MAX4209 |
M
Ultra-Low Offset/Drift, Precision
Instrumentation Amplifiers with REF Buffer
______________________________________________________________________________________
13
Applications Information
Setting the Gain (MAX4208)
Connect a resistive divider from OUT to REF with the cen-
ter tap connected to FB to set the gain for the MAX4208
(see the
Typical Application Circuit
). Calculate the gain
using the following formula:
Choose a value for R1
≤
1k
Ω
. Resistor accuracy ratio
directly affects gain accuracy. Resistor sum less than
10k
Ω
should not be used because their loading can
slightly affect output accuracy.
Input Common Mode vs.
Input Differential-Voltage Range
Traditional three-op amp instrumentation amplifiers
have a defined relationship between the maximum
input differential voltage and maximum input common-
mode voltage that arises from saturation of intermediate
amplifier stages. This correlation is frequently repre-
sented as a hexagon graph of input common-mode
voltage vs. output voltage for the instrumentation ampli-
fier shown in Figure 3. Application limitations hidden in
this graph are:
The input common-mode voltage range does not
include the negative supply rail, and so no amplifi-
cation is possible for inputs near ground for single-
supply applications.
Input differential voltages can be amplified with
maximum gain only over a limited range of input
common-mode voltages (i.e., range of y-axis for max
range of x-axis is limited).
If large amplitude common-mode voltages need to
be rejected, differential voltages cannot be amplified
with a maximum gain possible (i.e., range of x-axis
for a maximum range of y-axis is limited). As a con-
sequence, a secondary high-gain amplifier is
required to follow the front-end instrumentation
amplifier.
The indirect current-feedback architecture of the
MAX4208/MAX4209 instrumentation amplifiers do not
suffer from any of these drawbacks. Figure 4 shows the
input common-mode voltage vs. output voltage graph
of indirect current-feedback architecture.
In contrast to three-op amp instrumentation amplifiers,
the MAX4208/MAX4209 features:
The input common-mode voltage range, which
includes the negative supply rail and is ideal for sin-
gle-supply applications.
Input differential voltages that can be amplified with
maximum gain over the entire range of input com-
mon-mode voltages.
Large common-mode voltages that can be rejected
at the same time differential voltages are amplified
with maximum gain, and therefore, no secondary
amplifier is required to follow the front-end instru-
mentation amplifier.
Gain Error Drift Over Temperature
Adjustable gain instrumentation amplifiers typically use a
single external resistor to set the gain. However, due to
differences in temperature drift characteristics between
the internal and external resistors, this leads to large
gain-accuracy drift over temperature. The MAX4208 is
an adjustable gain instrumentation amplifier that uses
two external resistors to set its gain. Since both resistors
are external to the device, layout and temperature coeffi-
cient matching of these parts deliver a significantly more
stable gain over operating temperatures.
The fixed gain, MAX4209T/H/K has both internal resistors
for excellent matching and tracking.
Use of External Capacitor C
FB
for Noise Reduction
Zero-drift chopper amplifiers include circuitry that con-
tinuously compensates the input offset voltage to deliver
precision and ultra-low temperature drift characteristics.
This self-correction circuitry causes a small additional
noise contribution at its operating frequency (a psuedo-
random clock around 45kHz for MAX4208/MAX4209).
For high-bit resolution ADCs, external filtering can signif-
icantly attenuate this additional noise. Simply adding a
feedback capacitor (C
FB
) between OUT and FB
reduces high-frequency gain, while retaining the excel-
lent precision DC characteristics. Recommended values
for C
FB
are between 1nF and 10nF. Additional anti-alias-
ing filtering at the output can further reduce this auto-
correction noise.
Capacitive-Load Stability
The MAX4208/MAX4209 are capable of driving capaci-
tive loads up to 200pF. Applications needing higher
capacitive drive capability may use an isolation resistor
between OUT and the load to reduce ringing on the
output signal. However, this reduces the gain accuracy
due to the voltage drop across the isolation resistor.
GAIN
R
R
1
=
+
2
1
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX4209EVKIT+ | 功能描述:放大器 IC 開發(fā)工具 MAX4209 Eval Kit RoHS:否 制造商:International Rectifier 產(chǎn)品:Demonstration Boards 類型:Power Amplifiers 工具用于評估:IR4302 工作電源電壓:13 V to 23 V |
| MAX4209HAUA+ | 功能描述:儀表放大器 Low Offset/Drift Instrumentation Amp RoHS:否 制造商:Texas Instruments 通道數(shù)量: 輸入補(bǔ)償電壓:150 V 可用增益調(diào)整: 最大輸入電阻:10 kOhms 共模抑制比（最小值）:88 dB 工作電源電壓:2.7 V to 36 V 電源電流:200 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:MSOP-8 封裝:Bulk |
| MAX4209HAUA+T | 功能描述:儀表放大器 Low Offset/Drift Instrumentation Amp RoHS:否 制造商:Texas Instruments 通道數(shù)量: 輸入補(bǔ)償電壓:150 V 可用增益調(diào)整: 最大輸入電阻:10 kOhms 共模抑制比（最小值）:88 dB 工作電源電壓:2.7 V to 36 V 電源電流:200 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:MSOP-8 封裝:Bulk |
| MAX420C/D | 功能描述:運算放大器 - 運放 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 |
| MAX420CPA | 功能描述:運算放大器 - 運放 Integrated Circuits (ICs) 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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