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參數資料
| 型號： | AD8221 |
| 廠商： | Analog Devices, Inc. |
| 元件分類： | 運動控制電子 |
| 英文描述： | Single Supply, Rail-to-Rail, Low Cost Instrumentation Amplifier |
| 中文描述： | 單電源，軌至軌，低成本儀表放大器 |
| 文件頁數： | 13/20頁 |
| 文件大?。?/td> | 1283K |
| 代理商： | AD8221 |
AD8221
THEORY OF OPERATION
Rev. A | Page 13 of 20
C1
C2
+V
S
+V
S
+IN
–IN
–V
S
–V
S
10k
10k
10k
400
400
10k
REF
OUTPUT
I
B
COMPENSATION
I
B
COMPENSATION
+V
S
–V
S
+V
S
–V
S
+V
S
V
B
I
I
R1
24.7k
24.7k
R
G
Q1
R2
Q2
–V
S
+V
S
–V
S
A2
A1
A3
0
Figure 42. Simplified Schematic
The AD8221 is a monolithic instrumentation amplifier based
on the classic 3-op amp topology. Input transistors Q1 and Q2
are biased at a fixed current, so that any differential input signal
will force the output voltages of A1 and A2 to change accor-
dingly. A signal applied to the input creates a current through
R
G
, R1, and R2, such that the outputs of A1 and A2 deliver the
correct voltage. Topologically, Q1, A1, R1 and Q2, A2, R2 can be
viewed as precision current feedback amplifiers. The amplified
differential and common-mode signals are applied to a dif-
ference amplifier that rejects the common-mode voltage but
amplifies the differential voltage. The difference amplifier
employs innovations that result in low output offset voltage as
well as low output offset voltage drift. Laser-trimmed resistors
allow for a highly accurate in-amp with gain error typically less
than 20 ppm and CMRR that exceeds 90 dB (G = 1).
Using superbeta input transistors and an I
B
compensation
scheme, the AD8221 offers extremely high input impedance,
low I
B
, low I
B
drift, low I
OS
, low input bias current noise, and
extremely low voltage noise of 8 nV/√Hz.
The transfer function of the AD8221 is
G
R
G
kΩ
4
49
1
+
=
Users can easily and accurately set the gain using a single,
standard resistor.
Since the input amplifiers employ a current feedback architec-
ture, the AD8221’s gain-bandwidth product increases with gain,
resulting in a system that does not suffer from the expected
bandwidth loss of voltage feedback architectures at higher gains.
In order to maintain precision even at low input levels, special
attention was given to the AD8221’s design and layout, resulting
in an in-amp whose performance satisfies the most demanding
applications.
A unique pinout enables the AD8221 to meet a CMRR
specification of 80 dB at 10 kHz (G = 1) and 110 dB at 1 kHz
(G = 1000). The balanced pinout, shown in Figure 43, reduces
the parasitics that had, in the past, adversely affected CMRR
performance. In addition, the new pinout simplifies board
layout because associated traces are grouped together. For
example, the gain setting resistor pins are adjacent to the inputs,
and the reference pin is next to the output.
8
7
6
5
1
2
3
4
–IN
R
G
R
G
+V
S
V
OUT
REF
–V
S
+IN
TOP VIEW
AD8221
0
Figure 43. Pinout Diagram
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相關代理商/技術參數 |
參數描述 |
|---|---|
| AD8221AC-P7 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Precision Instrumentation Amplifier |
| AD8221AR | 功能描述:IC AMP INST PREC LN 18MA 8SOIC RoHS:否 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標準包裝:150 系列:- 放大器類型:音頻 電路數:2 輸出類型:- 轉換速率:5 V/µs 增益帶寬積:12MHz -3db帶寬:- 電流 - 輸入偏壓:100nA 電壓 - 輸入偏移:500µV 電流 - 電源:6mA 電流 - 輸出 / 通道:50mA 電壓 - 電源，單路/雙路(±):4 V ~ 32 V，±2 V ~ 16 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-TSSOP（0.173"，4.40mm 寬） 供應商設備封裝:8-TSSOP 包裝:管件 |
| AD8221ARM | 功能描述:IC AMP INST PREC LN 18MA 8MSOP RoHS:否 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標準包裝:50 系列:- 放大器類型:J-FET 電路數:2 輸出類型:- 轉換速率:13 V/µs 增益帶寬積:3MHz -3db帶寬:- 電流 - 輸入偏壓:65pA 電壓 - 輸入偏移:3000µV 電流 - 電源:1.4mA 電流 - 輸出 / 通道:- 電壓 - 電源，單路/雙路(±):7 V ~ 36 V，±3.5 V ~ 18 V 工作溫度:-40°C ~ 85°C 安裝類型:通孔 封裝/外殼:8-DIP（0.300"，7.62mm） 供應商設備封裝:8-PDIP 包裝:管件 |
| AD8221ARM-REEL | 功能描述:IC AMP INST PREC LN 18MA 8MSOP RoHS:否 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標準包裝:100 系列:- 放大器類型:通用 電路數:1 輸出類型:- 轉換速率:0.2 V/µs 增益帶寬積:- -3db帶寬:- 電流 - 輸入偏壓:100pA 電壓 - 輸入偏移:30µV 電流 - 電源:380µA 電流 - 輸出 / 通道:- 電壓 - 電源，單路/雙路(±):±2 V ~ 18 V 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 供應商設備封裝:8-SO 包裝:管件 |
| AD8221ARMREEL7 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Precision Instrumentation Amplifier |
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