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| 型号： | AD8221 |
| 厂商： | Analog Devices, Inc. |
| 元件分类： | 运动控制电子 |
| 英文描述： | Single Supply, Rail-to-Rail, Low Cost Instrumentation Amplifier |
| 中文描述： | 单电源，轨至轨，低成本仪表放大器 |
| 文件页数： | 15/20页 |
| 文件大小： | 1283K |
| 代理商： | AD8221 |
AD8221
REFERENCE TERMINAL
As shown in Figure 42, the reference terminal, REF, is at one end
of a 10 kΩ resistor. The instrumentation amplifier’s output is
referenced to the voltage on the REF terminal; this is useful
when the output signal needs to be offset to a precise midsupply
level. For example, a voltage source can be tied to the REF pin to
level-shift the output so that the AD8221 can interface with an
ADC. The allowable reference voltage range is a function of the
gain, input and supply voltage. The REF pin should not exceed
either +V
S
or –V
S
by more than 0.5 V.
Rev. A | Page 15 of 20
For best performance, source impedance to the REF terminal
should be kept low, since parasitic resistance can adversely affect
CMRR and gain accuracy.
POWER SUPPLY REGULATION AND BYPASSING
A stable dc voltage should be used to power the instrumenta-
tion amplifier. Noise on the supply pins may adversely affect
performance. Bypass capacitors should be used to decouple the
amplifier.
A 0.1 μF capacitor should be placed close to each supply pin. As
shown in Figure 47, a 10 μF tantalum capacitor may be used
further away from the part. In most cases, it may be shared by
other precision integrated circuits.
Figure 46
AD8221
+V
S
+IN
–IN
LOAD
REF
0.1
μ
F
10
μ
F
0.1
μ
F
10
μ
F
–V
S
V
OUT
0
Figure 47. Supply Decoupling,. REF and Output Referred to Local Ground
INPUT BIAS CURRENT RETURN PATH
The AD8221’s input bias current must have a return path to
common. When the source, such as a thermocouple, cannot
provide a return current path, one should be created, as shown
in Figure 48.
+V
S
REF
TRANSFORMER
THERMOCOUPLE
–V
S
AD8221
+V
S
REF
–V
S
AD8221
CAPACITOR COUPLED
+V
S
REF
C
R
R
C
–V
S
AD8221
1
f
HIGH-PASS
=2
π
RC
0
Figure 48. Creating an I
BIAS
Path
INPUT PROTECTION
All terminals of the AD8221 are protected against ESD
1
. In
addition, the input structure allows for dc overload conditions
below the negative supply, –Vs. The internal 400 resistors
limit current in the event of a negative fault condition. However,
in the case of a dc overload voltage above the positive supply,
+Vs, a large current would flow directly through the ESD diode
to the positive rail. Therefore, an external resistor should be
used in series with the input to limit current for voltages above
+Vs. In either scenario, the AD8221 can safely handle a
continuous 6 mA current, I = V
IN
/R
EXT
for positive overvoltage
and I = V
IN
/(400 + R
EXT
) for negative overvoltage.
For applications where the AD8221 encounters extreme
overload voltages, as in cardiac defibrillators, external series
resistors and low leakage diode clamps such as BAV199Ls,
FJH1100s, or SP720s should be used.
1
1 kV—Human Body Model.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| AD8221AC-P7 | 制造商:AD 制造商全称:Analog Devices 功能描述:Precision Instrumentation Amplifier |
| AD8221AR | 功能描述:IC AMP INST PREC LN 18MA 8SOIC RoHS:否 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 标准包装:150 系列:- 放大器类型:音频 电路数:2 输出类型:- 转换速率:5 V/µs 增益带宽积:12MHz -3db带宽:- 电流 - 输入偏压:100nA 电压 - 输入偏移:500µV 电流 - 电源:6mA 电流 - 输出 / 通道:50mA 电压 - 电源，单路/双路(±):4 V ~ 32 V，±2 V ~ 16 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-TSSOP（0.173"，4.40mm 宽） 供应商设备封装:8-TSSOP 包装:管件 |
| AD8221ARM | 功能描述:IC AMP INST PREC LN 18MA 8MSOP RoHS:否 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 标准包装:50 系列:- 放大器类型:J-FET 电路数:2 输出类型:- 转换速率:13 V/µs 增益带宽积:3MHz -3db带宽:- 电流 - 输入偏压:65pA 电压 - 输入偏移:3000µV 电流 - 电源:1.4mA 电流 - 输出 / 通道:- 电压 - 电源，单路/双路(±):7 V ~ 36 V，±3.5 V ~ 18 V 工作温度:-40°C ~ 85°C 安装类型:通孔 封装/外壳:8-DIP（0.300"，7.62mm） 供应商设备封装:8-PDIP 包装:管件 |
| AD8221ARM-REEL | 功能描述:IC AMP INST PREC LN 18MA 8MSOP RoHS:否 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 标准包装:100 系列:- 放大器类型:通用 电路数:1 输出类型:- 转换速率:0.2 V/µs 增益带宽积:- -3db带宽:- 电流 - 输入偏压:100pA 电压 - 输入偏移:30µV 电流 - 电源:380µA 电流 - 输出 / 通道:- 电压 - 电源，单路/双路(±):±2 V ~ 18 V 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 供应商设备封装:8-SO 包装:管件 |
| AD8221ARMREEL7 | 制造商:AD 制造商全称:Analog Devices 功能描述:Precision Instrumentation Amplifier |
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