參數(shù)資料
型號(hào): MAX4208
廠商: Maxim Integrated Products, Inc.
元件分類(lèi): 運(yùn)動(dòng)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(yè)數(shù): 14/17頁(yè)
文件大?。?/td> 263K
代理商: MAX4208
M
Ultra-Low Offset/Drift, Precision
Instrumentation Amplifiers with REF Buffer
14
______________________________________________________________________________________
Power-Supply Bypass and Layout
Good layout technique optimizes performance by
decreasing the amount of stray capacitance at the
instrumentation amplifier’s gain-setting pins (OUT, FB,
and REF). Excess capacitance produces peaking in
the amplifier’s frequency response. To decrease stray
capacitance, minimize trace lengths by placing exter-
nal components as close as possible to the instrumen-
tation amplifier. Unshielded long traces at the inputs of
the instrumentation amplifier degrade the CMRR and
pick-up noise. This produces inaccurate output in high-
gain configurations. Use shielded or coax cables to
connect the inputs of the instrumentation amplifier.
Since the MAX4208/MAX4209 feature ultra-low input
offset voltage, board leakage and thermocouple effects
can easily introduce errors in the input offset voltage
readings when used with high-impedance signal
sources. Minimize board leakage current and thermo-
couple effects by thoroughly cleaning the board and
placing the matching components very close to each
other and with appropriate orientation. For best perfor-
mance, bypass each power supply to ground with a
separate 0.1μF capacitor.
For noisy digital environments, the use of multilayer
PCB with separate ground and power-supply planes is
recommended. Keep digital signals far away from the
sensitive analog inputs.
Refer to the MAX4208 or MAX4209 Evaluation Kit data
sheets for good layout examples.
Low-Side Current-Sense Amplifier
The use of indirect current-feedback architecture
makes the MAX4208/MAX4209 ideal for low-side cur-
rent-sensing applications, i.e., where the current in the
circuit ground needs to be measured by means of a
small sense resistor. In these situations, the input com-
mon-mode voltage is allowed to be at or even slightly
below ground (V
SS
- 0.1V).
If the currents to be measured are bidirectional, con-
nect REFIN/MODE to V
DD
/2 to get full dynamic range
for each direction. If the currents to be measured are
unidirectional, both REFIN/MODE and REF can be tied
to GND. However, VOL limitations can limit low-current
measurement. If currents need to be measured down to
0A, bias REFIN/MODE to a voltage above 0.2V to acti-
vate the internal buffer and to stay above amplifier VOL,
and measure both OUT and REF with a differential
input ADC.
Low-Voltage, High-Side
Current-Sense Amplifier
Power management is a critical area in high-perfor-
mance portable devices such as notebook computers.
Modern digital processors and ASICs are using smaller
transistor geometries to increase speed, reduce size,
and also lower their operating core voltages (typically
0.9V to 1.25V). The MAX4208/MAX4209 instrumentation
amplifiers can be used as a nearly zero voltage-drop,
current-sense amplifier (see Figure 5).
V
CM
V
CC
V
CM-MAX
3/4 V
CC
1/2 V
CC
1/4 V
CC
0
V
CC
/2
V
CC
V
OUT
( = GAIN x V
DIFF
+ V
REF
)
V
REF
= 1/2 V
CC
CLASSIC THREE OP-AMP INA
V
CM
V
DD
V
CM-MAX
0
V
DD
/2
V
DD
V
OUT
( = GAIN x V
DIFF
+ V
REF
)
V
REF
= 1/2 V
DD
MAX4208/MAX4209
Figure 3. Limited Common Mode vs. Output Voltage of a
Three Op-Amp INA
Figure 4. Input Common Mode vs. Output Voltage of
MAX4208/MAX4209 Includes 0V (GND)
相關(guān)PDF資料
PDF描述
MAX4209 Ultra-Low Offset/Drift, Precision Instrumentation Amplifiers with REF Buffer
MAX4215ESA High-Speed, Single-Supply, Gain of @, Closed-Loop, Rail-to-Rail Buffers with Enable
MAX4219EEE High-Speed, Single-Supply, Gain of @, Closed-Loop, Rail-to-Rail Buffers with Enable
MAX4217ESA High-Speed, Single-Supply, Gain of @, Closed-Loop, Rail-to-Rail Buffers with Enable
MAX4214 High-Speed, Single-Supply, Gain of @, Closed-Loop, Rail-to-Rail Buffers with Enable
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX4208AUA+ 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
MAX4208AUA+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
MAX4208EVKIT+ 功能描述:放大器 IC 開(kāi)發(fā)工具 MAX4208 Eval Kit RoHS:否 制造商:International Rectifier 產(chǎn)品:Demonstration Boards 類(lèi)型:Power Amplifiers 工具用于評(píng)估:IR4302 工作電源電壓:13 V to 23 V
MAX4209EVKIT+ 功能描述:放大器 IC 開(kāi)發(fā)工具 MAX4209 Eval Kit RoHS:否 制造商:International Rectifier 產(chǎn)品:Demonstration Boards 類(lèi)型:Power Amplifiers 工具用于評(píng)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