AD8622ARMZ [ADI]
Dual, Low Power, Precision Rail-to-Rail Output Op Amp; 双通道，低功耗，精密，轨到轨输出运算放大器
| 型号： | AD8622ARMZ |
| 厂家： | 
ADI |
| 描述： | Dual, Low Power, Precision Rail-to-Rail Output Op Amp |
| 文件： | 总20页 (文件大小：591K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Dual, Low Power, Precision
Rail-to-Rail Output Op Amp
AD8622
FEATURES
PIN CONFIGURATIONS
Very low offset voltage
125 μV maximum
OUT A
–IN A
+IN A
V–
1
2
3
4
8
7
6
5
V+
AD8622
OUT B
–IN B
+IN B
TOP VIEW
(Not to Scale)
Supply current: 215 μA/amp typical
Input bias current: 200 pA maximum
Low input offset voltage drift: 1.2 μV/°C maximum
Very low voltage noise: 11 nV/√Hz
Operating temperature: −40°C to +125°C
Rail-to-rail output swing
Figure 1. 8-Lead Narrow-Body SOIC
OUT A
–IN A
+IN A
V–
1
2
3
4
8
7
6
5
V+
AD8622
OUT B
–IN B
+IN B
TOP VIEW
(Not to Scale)
Unity gain stable
2.5 V to 15 V operation
Figure 2. 8-Lead MSOP
APPLICATIONS
Portable precision instrumentation
Laser diode control loops
Strain gage amplifiers
Medical instrumentation
Thermocouple amplifiers
GENERAL DESCRIPTION
Table 1. Low Power Op Amps
The AD8622 is a dual, precision rail-to-rail output operational
amplifier with a low supply current of only 350 μA maximum
over temperature and supply voltages. It also offers ultralow
offset, drift, and voltage noise combined with very low input
bias current over the full operating temperature range.
Supply
40 V
36 V
12 V to 16 V
5 V
Single
OP97
OP777
OP1177
OP727
OP2177
AD706
OP747
OP4177
AD704
OP196
AD8663
OP296
AD8603
Dual
OP297
OP497
AD8607
AD8609
AD8667
With typical offset voltage of only 10 μV, offset drift of 0.5 μV/°C,
and noise of only 0.2 ꢀV p-p (0.1 Hz to 10 Hz), it is perfectly
suited for applications where large error sources cannot be
tolerated. Many systems can take advantage of the low noise,
dc precision, and rail-to-rail output swing provided by the
AD8622 to maximize the signal-to-noise ratio and dynamic
range for low power operation. The AD8622 is specified for the
extended industrial temperature range of −40°C to +125°C and
is available in lead-free SOIC and MSOP packages.
Quad
OP496
AD8669
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registeredtrademarks arethe property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.461.3113
www.analog.com
©2009 Analog Devices, Inc. All rights reserved.
AD8622
TABLE OF CONTENTS
Features .............................................................................................. 1
ESD Caution...................................................................................5
Typical Performance Characteristics ..............................................6
Applications Information.............................................................. 15
Input Protection ......................................................................... 15
Phase Reversal ............................................................................ 15
Micropower Instrumentation Amplifier................................. 15
Hall Sensor Signal Conditioning.............................................. 16
Simplified Schematic...................................................................... 17
Outline Dimensions....................................................................... 18
Ordering Guide .......................................................................... 18
Applications....................................................................................... 1
Pin Configurations ........................................................................... 1
General Description......................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Electrical Characteristics— 15 V Operation........................... 3
Electrical Characteristics— 2.5 V Operation.......................... 4
Absolute Maximum Ratings............................................................ 5
Thermal Resistance ...................................................................... 5
REVISION HISTORY
7/09—Revision 0: Initial Version
Rev. 0 | Page 2 of 20
AD8622
SPECIFICATIONS
ELECTRICAL CHARACTERISTICS— 15 V OPERATION
VS = 15 V, VCM = 0 V, TA = +25°C, unless otherwise specified.
Table 2.
Parameter
Symbol Conditions
Min
Typ
Max
Unit
INPUT CHARACTERISTICS
Offset Voltage
VOS
10
125
230
1.2
200
500
200
500
+13.8
μV
μV
μV/°C
pA
pA
pA
pA
V
dB
dB
dB
dB
GΩ
TΩ
pF
−40°C ≤ TA ≤ +125°C
Offset Voltage Drift
Input Bias Current
ΔVOS/ΔT −40°C ≤ TA ≤ +125°C
IB
0.5
45
−40°C ≤ TA ≤ +125°C
Input Offset Current
IOS
35
−40°C ≤ TA ≤ +125°C
Input Voltage Range
Common-Mode Rejection Ratio
−13.8
125
112
125
120
CMRR
AVO
VCM = −13.8 V to +13.8 V
−40°C ≤ TA ≤ +125°C
RL = 10 kΩ, VO = −13.5 V to +13.5 V
−40°C ≤ TA ≤ +125°C
135
137
Open-Loop Gain
Input Resistance, Differential Mode
Input Resistance, Common Mode
Input Capacitance, Differential Mode
Input Capacitance, Common Mode
OUTPUT CHARACTERISTICS
RINDM
RINCM
CINDM
CINCM
1
1
5.5
3
pF
Output Voltage High
VOH
RL = 100 kΩ to ground
−40°C ≤ TA ≤ +125°C
RL = 10 kΩ to ground
−40°C ≤ TA ≤ +125°C
RL = 100 kΩ to ground
−40°C ≤ TA ≤ +125°C
RL = 10 kΩ to ground
−40°C ≤ TA ≤ +125°C
14.94 14.97
14.84
14.86 14.89
14.75
V
V
V
V
V
V
V
V
Output Voltage Low
VOL
−14.97 −14.94
−14.92
−14.89 −14.90
−14.80
Short-Circuit Current
Closed-Loop Output Impedance
POWER SUPPLY
ISC
ZOUT
40
1.5
mA
Ω
f = 1 kHz, AV = 1
Power Supply Rejection Ratio
PSRR
ISY
VS = 2.0 V to 18.0 V
−40°C ≤ TA ≤ +125°C
IO = 0 mA
125
120
145
dB
dB
μA
μA
Supply Current/Amplifier
215
250
350
−40°C ≤ TA ≤ +125°C
DYNAMIC PERFORMANCE
Slew Rate
Gain Bandwidth Product
SR
GBP
ΦM
RL = 10 kΩ, AV = 1
CL = 35 pF, AV = 1
CL = 35 pF, AV = 1
0.48
600
72
V/μs
kHz
Degrees
Phase Margin
NOISE PERFORMANCE
Voltage Noise
Voltage Noise Density
Uncorrelated Current Noise Density
Correlated Current Noise Density
en p-p
en
in
f = 0.1 Hz to 10 Hz
f = 1 kHz
f = 1 kHz
0.2
11
0.15
0.06
μV p-p
nV/√Hz
pA/√Hz
pA/√Hz
in
f = 1 kHz
Rev. 0 | Page 3 of 20
AD8622
ELECTRICAL CHARACTERISTICS— 2.5 V OPERATION
VS = 2.5 V, VCM = 0 V, TA = +25°C, unless otherwise specified.
Table 3.
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
INPUT CHARACTERISTICS
Offset Voltage
VOS
10
125
230
1.2
μV
μV
μV/°C
pA
pA
pA
pA
V
dB
dB
dB
dB
GΩ
TΩ
pF
−40°C ≤ TA ≤ +125°C
−40°C ≤ TA ≤ +125°C
Offset Voltage Drift
Input Bias Current
ΔVOS/ΔT
IB
0.5
30
200
400
200
300
+1.3
−40°C ≤ TA ≤ +125°C
Input Offset Current
IOS
25
−40°C ≤ TA ≤ +125°C
−40°C ≤ TA ≤ +125°C
VCM = −1.3 V to +1.3 V
−40°C ≤ TA ≤ +125°C
RL = 10 kΩ, VO = −2.0 V to +2.0 V
−40°C ≤ TA ≤ +125°C
Input Voltage Range
Common-Mode Rejection Ratio
−1.3
110
107
118
109
CMRR
AVO
120
135
Open-Loop Gain
Input Resistance, Differential Mode
Input Resistance, Common Mode
Input Capacitance, Differential Mode
Input Capacitance, Common Mode
OUTPUT CHARACTERISTICS
RINDM
RINDM
CINDM
CINCM
1
1
5.5
3
pF
Output Voltage High
VOH
RL = 100 kΩ to ground
−40°C ≤ TA ≤ +125°C
RL = 10 kΩ to ground
−40°C ≤ TA ≤ +125°C
RL = 100 kΩ to ground
−40°C ≤ TA ≤ +125°C
RL = 10 kΩ to ground
−40°C ≤ TA ≤ +125°C
2.45
2.41
2.40
2.36
2.49
2.45
V
V
V
V
V
V
V
V
Output Voltage Low
VOL
−2.49 −2.45
−2.41
−2.45 −2.40
−2.36
Short-Circuit Current
Closed-Loop Output Impedance
POWER SUPPLY
ISC
ZOUT
30
2
mA
Ω
f = 1 kHz, AV = 1
Power Supply Rejection Ratio
PSRR
ISY
VS = 2.0 V to 18.0 V
−40°C ≤ TA ≤ +125°C
IO = 0 mA
125
120
145
dB
dB
μA
μA
Supply Current/Amplifier
175
225
310
−40°C ≤ TA ≤ +125°C
DYNAMIC PERFORMANCE
Slew Rate
Gain Bandwidth Product
SR
GBP
ΦM
RL = 10 kΩ, AV = 1
CL = 35 pF, AV = 1
CL = 35 pF, AV = 1
0.28
580
72
V/μs
kHz
Degrees
Phase Margin
NOISE PERFORMANCE
Voltage Noise
Voltage Noise Density
Uncorrelated Current Noise Density
Correlated Current Noise Density
en p-p
en
in
f = 0.1 Hz to 10 Hz
f = 1 kHz
f = 1 kHz
0.2
12
0.15
0.07
μV p-p
nV/√Hz
pA/√Hz
pA/√Hz
in
f = 1 kHz
Rev. 0 | Page 4 of 20
AD8622
ABSOLUTE MAXIMUM RATINGS
Table 4.
Parameter
THERMAL RESISTANCE
Rating
θJA is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages. This
was measured using a standard 4-layer board.
Supply Voltage
Input Voltage
Input Current1
Differential Input Voltage2
Output Short-Circuit Duration to GND
Storage Temperature Range
Operating Temperature Range
Junction Temperature Range
Lead Temperature (Soldering, 60 sec)
18 V
V supply
10 mA
10 V
Indefinite
−65°C to +150°C
−40°C to +125°C
−65°C to +150°C
300°C
Table 5. Thermal Resistance
Package Type
θJA
θJC
43
53
Unit
°C/W
°C/W
8-Lead SOIC_N (R-8)
8-Lead MSOP (RM-8)
158
185
ESD CAUTION
1 The input pins have clamp diodes to the power supply pins. The input
current should be limited to 10 mA or less whenever input signals exceed
the power supply rail by 0.5 V.
2 Differential input voltage is limited to 10 V or the supply voltage, whichever is less.
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
Rev. 0 | Page 5 of 20
AD8622
TYPICAL PERFORMANCE CHARACTERISTICS
TA = 25°C, unless otherwise noted.
60
60
50
40
30
V
V
= ±15V
= 0V
V
V
= ±2.5V
= 0V
SY
SY
CM
CM
50
40
30
20
10
0
20
10
0
–100 –80 –60 –40 –20
0
20
(µV)
40
60
80
100
–100 –80 –60 –40 –20
0
20
(µV)
40
60
80 100
V
V
OS
OS
Figure 3. Input Offset Voltage Distribution
Figure 6. Input Offset Voltage Distribution
60
50
40
30
60
50
40
30
V
= ±15V
V
= ±2.5V
SY
–40°C ≤ T ≤ +125°C
SY
–40°C ≤ T ≤ +125°C
A
A
20
10
0
20
10
0
0
0.2
0.4
0.6
(µV/°C)
0.8
1.0
1.2
0
0.2
0.4
0.6
TCV (µV/°C)
OS
0.8
1.0
1.2
TCV
OS
Figure 4. Input Offset Voltage Drift Distribution
Figure 7. Input Offset Voltage Drift Distribution
50
40
50
40
V
= ±15V
SY
V
= ±2.5V
SY
–40°C
+25°C
30
30
20
20
–40°C
10
10
0
0
+25°C
+85°C
–10
–20
–30
–40
–50
–10
–20
–30
–40
–50
+85°C
+125°C
+125°C
0
5
10
15
(V)
20
25
30
–2.5
–1.5
–0.5
0.5
1.5
2.5
V
V
(V)
CM
CM
Figure 5. Input Offset Voltage vs. Common-Mode Voltage
Figure 8. Input Offset Voltage vs. Common-Mode Voltage
Rev. 0 | Page 6 of 20
AD8622
40
30
40
20
V
= ±15V
V
= ±2.5V
SY
SY
I
I
+
B
20
0
I
I
+
–
B
10
0
–20
–40
–60
–80
–
B
–10
–20
–30
–40
B
–50
–25
0
25
50
75
100
125
–50
–25
0
25
50
75
100
125
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 9. Input Bias Current vs. Temperature
Figure 12. Input Bias Current vs. Temperature
60
40
50
25
V
= ±15V
V
= ±2.5V
SY
SY
0
20
–25
–50
–75
–100
–125
–150
0
–20
–40
–60
0
5
10
15
20
25
30
0
1
2
3
4
5
V
(V)
V
(V)
CM
CM
Figure 10. Input Bias Current vs. Common-Mode Voltage
Figure 13. Input Bias Current vs. Common-Mode Voltage
100k
10k
1k
100k
10k
1k
V
= ±15V
V
= ±2.5V
SY
SY
V
– V
OH
CC
V
– V
OH
CC
100
100
V
– V
EE
OL
V
– V
EE
OL
10
1
10
1
0.001
0.01
0.1
1
10
100
0.001
0.01
0.1
1
10
100
LOAD CURRENT (mA)
LOAD CURRENT (mA)
Figure 11. Output Voltage to Supply Rail vs. Load Current
Figure 14. Output Voltage to Supply Rail vs. Load Current
Rev. 0 | Page 7 of 20
AD8622
0.16
0.06
0.05
0.04
0.03
0.02
V
R
= ±15V
= 10kΩ
V
= ±2.5V
SY
SY
R
= 10kΩ
L
L
0.14
0.12
0.10
0.08
V
– V
OH
V
– V
OH
CC
CC
0.06
0.04
0.02
V
– V
EE
OL
V
– V
EE
OL
0.01
0
0
–50
–25
0
25
50
75
100
125
–50
–25
0
25
50
75
100
125
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 15. Output Voltage to Supply Rail vs. Temperature
Figure 18. Output Voltage to Supply Rail vs. Temperature
100
80
100
80
100
80
100
80
V
R
= ±15V
= 10kΩ
V
R
= ±2.5V
= 10kΩ
SY
SY
L
L
PHASE
PHASE
60
60
60
60
40
40
40
40
GAIN
GAIN
20
0
20
0
20
0
20
0
–20
–20
–20
–20
–40
1k
–40
10M
–40
1k
–40
10M
10k
100k
FREQUENCY (Hz)
1M
10k
100k
FREQUENCY (Hz)
1M
Figure 16. Open-Loop Gain and Phase vs. Frequency
Figure 19. Open-Loop Gain and Phase vs. Frequency
60
50
40
30
20
10
0
60
50
40
30
20
10
0
V
R
= ±15V
= 10kΩ
V
R
= ±2.5V
SY
SY
= 10kΩ
L
L
A
= 100
= 10
A
= 100
= 10
V
V
A
A
V
V
A
= 1
A = 1
V
V
–10
–20
–30
–10
–20
–30
–40
100
–40
100
1k
10k
100k
1M
10M
1k
10k
100k
1M
10M
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 17. Closed-Loop Gain vs. Frequency
Figure 20. Closed-Loop Gain vs. Frequency
Rev. 0 | Page 8 of 20
AD8622
10k
1k
10k
1k
V
= ±15V
V
= ±2.5V
SY
SY
A
= 100
V
A
= 100
V
A
= 10
V
A
= 10
V
100
10
100
10
A
= 1
V
A
= 1
V
1
1
0.1
100
0.1
100
1k
10k
FREQUENCY (Hz)
100k
1M
1k
10k
FREQUENCY (Hz)
100k
1M
Figure 21. Output Impedance vs. Frequency
Figure 24. Output Impedance vs. Frequency
120
100
80
120
100
80
V
= ±15V
V
= ±2.5V
SY
SY
60
60
40
40
20
0
20
0
10
100
1k
10k
100k
1M
10
100
1k
10k
100k
1M
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 22. CMRR vs. Frequency
Figure 25. CMRR vs. Frequency
120
100
80
120
100
80
V
= ±15V
V
= ±2.5V
SY
SY
PSRR+
PSRR–
PSRR+
PSRR–
60
60
40
40
20
0
20
0
10
100
1k
10k
100k
1M
10
100
1k
10k
100k
1M
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 23. PSRR vs. Frequency
Figure 26. PSRR vs. Frequency
Rev. 0 | Page 9 of 20
AD8622
50
50
45
V
A
R
= ±15V
= 1
= 10kΩ
V
= ±2.5V
SY
SY
45
A
R
= 1
= 10kΩ
V
L
V
L
40
35
30
25
40
35
30
25
OS–
OS–
OS+
OS+
20
15
10
20
15
10
5
0
5
0
0.01
0.1
1
10
100
0.01
0.1
1
10
100
CAPACITANCE (nF)
CAPACITANCE (nF)
Figure 27. Small-Signal Overshoot vs. Load Capacitance
Figure 30. Small-Signal Overshoot vs. Load Capacitance
V
= ±2.5V
= 1
= 10kΩ
= 100pF
SY
V
= ±15V
= 1
= 10kΩ
= 100pF
SY
A
R
C
V
L
L
A
R
C
V
L
L
TIME (40µs/DIV)
TIME (40µs/DIV)
Figure 28. Large-Signal Transient Response
Figure 31. Large-Signal Transient Response
V
= ±15V
V
= ±2.5V
SY
SY
A
R
C
= 1
= 10kΩ
= 100pF
A
R
C
= 1
= 10kΩ
= 100pF
V
L
L
V
L
L
TIME (10µs/DIV)
TIME (10µs/DIV)
Figure 29. Small-Signal Transient Response
Figure 32. Small-Signal Transient Response
Rev. 0 | Page 10 of 20
AD8622
0.4
0.2
0
0.4
0.2
0
V
A
R
= ±15V
= –100
= 10kΩ
V
A
R
= ±2.5V
= –100
= 10kΩ
SY
SY
V
L
V
L
INPUT
INPUT
OUTPUT
OUTPUT
0
0
–10
–20
–1
–2
–3
TIME (20µs/DIV)
TIME (20µs/DIV)
Figure 33. Negative Overload Recovery
Figure 36. Negative Overload Recovery
0.2
0
0.2
0
INPUT
INPUT
–0.2
–0.2
20
10
0
3
2
1
OUTPUT
OUTPUT
V
A
R
= ±15V
= –100
= 10kΩ
V
A
R
= ±2.5V
= –100
= 10kΩ
SY
SY
–10
–20
0
V
L
V
L
–1
TIME (20µs/DIV)
TIME (20µs/DIV)
Figure 34. Positive Overload Recovery
Figure 37. Positive Overload Recovery
12
12
V
= ±15V
V
= ±15V
SY
SY
A
= –1
A = +1
V
V
10
8
10
8
0.1%
0.1%
0.01%
0.01%
6
6
4
4
2
2
0
0
0
5
10
15
20
25
30
35
0
5
10
15
20
25
30
35
SETTLING TIME (µs)
SETTLING TIME (µs)
Figure 35. Output Step vs. Settling Time
Figure 38. Output Step vs. Settling Time
Rev. 0 | Page 11 of 20
AD8622
100
100
V
= ±2.5V
V
= ±15V
SY
SY
10
10
1
1
1
1
10
100
1k
10
100
1k
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 39. Voltage Noise Density vs. Frequency
Figure 42. Voltage Noise Density vs. Frequency
1
1
R
R
S1
V
= ±15V
S1
V
= ±2.5V
SY
SY
R
R
S2
S2
UNCORRELATED
S1
UNCORRELATED
S1
R
= 0Ω
R
= 0Ω
CORRELATED
0.1
0.1
CORRELATED
R
= R
S1
S2
R
= R
S1
S2
0.01
0.01
1
10
100
1k
1
10
100
1k
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 40. Current Noise Density vs. Frequency
Figure 43. Current Noise Density vs. Frequency
V
= ±15V
V
= ±2.5V
SY
SY
TIME (1s/DIV)
TIME (1s/DIV)
Figure 41. 0.1 Hz to 10 Hz Noise
Figure 44. 0.1 Hz to 10 Hz Noise
Rev. 0 | Page 12 of 20
AD8622
0.35
0.30
0.35
0.30
+125°C
0.25
0.20
0.15
0.10
0.05
0
+85°C
+25°C
0.25
0.20
0.15
V
= ±15V
SY
–40°C
V
= ±2.5V
SY
0.10
0.05
–0.05
0
2
4
6
8
10
(±V)
12
14
16
18
–50
–25
0
25
50
75
100
125
V
TEMPERATURE (°C)
SY
Figure 45. Supply Current vs. Supply Voltage
Figure 48. Supply Current vs. Temperature
1
0.1
1
0.1
V
= ±2.5V
V
= ±15V
SY
SY
f = 1kHz
R
f = 1kHz
R
= 10kΩ
= 10kΩ
L
L
0.01
0.01
0.001
0.001
0.0001
0.0001
0.001
0.01
0.1
1
10
0.001
0.01
0.1
1
10
AMPLITUDE (V rms)
AMPLITUDE (V rms)
Figure 49. THD + Noise vs. Amplitude
Figure 46. THD + Noise vs. Amplitude
0.1
0.1
V
= ±15V
SY
V
R
V
= ±2.5V
= 10kΩ
= 300mV rms
SY
R
= 10kΩ
= 300mV rms
L
L
V
IN
IN
0.01
0.001
0.01
0.001
0.0001
0.0001
10
100
1k
10k
100k
10
100
1k
10k
100k
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 47. THD + Noise vs. Frequency
Figure 50. THD + Noise vs. Frequency
Rev. 0 | Page 13 of 20
AD8622
0
–20
–40
–60
100kΩ
1kΩ
R
L
–80
–100
–120
V
= ±2.5V TO ±15V
SY
R
= 10kΩ
L
–140
10
100
1k
FREQUENCY (Hz)
10k
100k
Figure 51. Channel Separation vs. Frequency
Rev. 0 | Page 14 of 20
AD8622
APPLICATIONS INFORMATION
V
INPUT PROTECTION
IN
V
= ±15V
SY
The maximum differential input voltage that can be applied to
the AD8622 is determined by the internal diodes connected
across its inputs and series resistors at each input. These internal
diodes and series resistors limit the maximum differential input
voltage to 10 V and are needed to prevent base-emitter junction
breakdown from occurring in the input stage of the AD8622
when very large differential voltages are applied. In addition,
the internal resistors limit the currents that flow through the
diodes. However, in applications where large differential voltages
can be inadvertently applied to the device, large currents may
still flow through these diodes. In such a case, external resistors
must be placed at both inputs of the op amp to limit the input
currents to 10 mA (see Figure 52).
V
OUT
TIME (200µs/DIV)
Figure 53. No Phase Reversal
MICROPOWER INSTRUMENTATION AMPLIFIER
The AD8622 is a dual, high precision, rail-to-rail output op amp
operating at just 215 ꢀA quiescent current per amplifier. Its
ultralow offset, offset drift, and voltage noise, combined with its
very low bias current and high common-mode rejection ratio
(CMRR), are ideally suited for high accuracy and micropower
instrumentation amplifier.
R1
R2
500Ω
500Ω
2
3
1/2
AD8622
1
Figure 54 shows the classic 2-op-amp instrumentation amplifier
with four resistors using the AD8622. The key to high CMRR
for this instrumentation amplifier are resistors that are well
matched from both the resistive ratio and the relative drift. For
true difference amplification, matching of the resistor ratio is
very important, where R3/R4 = R1/R2. Assuming perfectly
matched resistors, the gain of the circuit is 1 + R2/R1, which is
approximately 100. Tighter matching of two op amps in one
package, like the AD8622, offers a significant boost in
Figure 52. Input Protection
PHASE REVERSAL
An undesired phenomenon, phase reversal (also known as
phase inversion) occurs in many op amps when one or both of
the inputs are driven beyond the specified input voltage range
(IVR), in effect reversing the polarity of the output. In some
cases, phase reversal can induce lockups and even cause
equipment damage as well as self destruction.
performance over the classical 3-op-amp configuration. Overall,
The AD8622 amplifiers have been carefully designed to prevent
output phase reversal when both inputs are maintained within
the specified input voltage range. In addition, even if one or
both inputs exceed the input voltage range but remain within
the supply rails, the output still does not phase reverse. Figure 53
shows the input/output waveforms of the AD8622 configured as a
unity-gain buffer with a supply voltage of 15 V.
the circuit only requires about 430 μA of supply current.
R3
10.1kΩ
R2
1MΩ
+15V
R4
1MΩ
+15V
–
R1
10.1kΩ
1/2
–
AD8622
1/2
V
V1
AD8622
+
+
O
V2
–15V
NOTES
1. V = 100(V2 – V1)
–15V
O
2. TYPICAL: 0.01mV < |V2 – V1| < 149.7mV
3. TYPICAL: –14.97V < V < +14.97V
O
4. USE MATCHED RESISTORS.
Figure 54. Micropower Instrumentation Amplifier
Rev. 0 | Page 15 of 20
AD8622
The ADR121 is a precision micropower 2.5 V voltage reference.
A precision voltage reference is required to hold a constant current
so that the Hall voltage only depends on the intensity of the mag-
netic field. Using the 4.12k:98.8k resistive divider, the bias
voltage of the Hall element is reduced to 100 mV, leading to only
250 μA of power consumption. The 3-op-amp in-amp
configuration of the AD8622 then increases the sensitivity to
55 mV/mT. Using the AD8622 to amplify the sensor signal can
reduce power while also achieving higher sensitivity. The total
current consumed is just 1.2 mA, resulting in 21× improvement in
sensitivity/power.
HALL SENSOR SIGNAL CONDITIONING
The AD8622 is also highly suitable for high accuracy, low power
signal conditioning circuits. One such use is in Hall sensor
signal conditioning (see Figure 55). The magnetic sensitivity of
a Hall element is proportional to the bias voltage applied across
it. With 1 V bias voltage, the Hall element consumes about
2.5 mA of supply current and has a sensitivity of 5.5 mV/mT
typical. To reduce power consumption, bias voltage must be
reduced, but at the risk of lower sensitivity. The only way to
achieve higher sensitivity is by introducing a gain using a
precision micropower amplifier. The AD8622, with all its
features, is well suited to amplify the sensitivity of the Hall
element.
V
V
SY
SY
+
C1
1/2
9.9kΩ
1µF TO 10µF
AD8622
HALL
ELEMENT
V
–
SY
ADR121 –2.5V
9.9kΩ
9.9kΩ
9.9kΩ
–
V
SY
4.12kΩ
98.8kΩ
1/2
400Ω
×4
C3
0.1µF
TO 10µF
200Ω
AD8622
+
C2
0.1µF
+
55mV
mT
9.9kΩ
1/2
AD8622
V
= 2.5V +
× MAGNETIC FIELD (mT)
OUT
+
V
SY
–
–
1/2
AD8622
9.9kΩ
+
NOTES
1. USE MATCHED RESISTORS FOR IN-AMP.
2. FOR INFORMATION ON C1, C2, AND C3, REFER TO ADR121 DATA SHEET.
Figure 55. Hall Sensor Signal Conditioning
Rev. 0 | Page 16 of 20
AD8622
SIMPLIFIED SCHEMATIC
V+
R3
R2
R1
Q10
Q11
C1
V
Q6
B2
Q3
V
B1
Q5
INPUT BIAS
CANCELLATION
CIRCUITRY
Q4
Q8
OUT x
500Ω
Q1
Q2
+IN x
D1
D2
500Ω
–IN x
Q7
Q12
Q9
D4
D3
V–
Figure 56. Simplified Schematic
Rev. 0 | Page 17 of 20
AD8622
OUTLINE DIMENSIONS
3.20
3.00
2.80
8
1
5
4
5.15
4.90
4.65
3.20
3.00
2.80
PIN 1
0.65 BSC
0.95
0.85
0.75
1.10 MAX
0.80
0.60
0.40
8°
0°
0.15
0.00
0.38
0.22
0.23
0.08
SEATING
PLANE
COPLANARITY
0.10
COMPLIANT TO JEDEC STANDARDS MO-187-AA
Figure 57. 8-Lead Mini Small Outline Package [MSOP]
(RM-8)
Dimensions shown in millimeters
5.00 (0.1968)
4.80 (0.1890)
8
1
5
4
6.20 (0.2441)
5.80 (0.2284)
4.00 (0.1574)
3.80 (0.1497)
0.50 (0.0196)
0.25 (0.0099)
1.27 (0.0500)
BSC
45°
1.75 (0.0688)
1.35 (0.0532)
0.25 (0.0098)
0.10 (0.0040)
8°
0°
0.51 (0.0201)
0.31 (0.0122)
COPLANARITY
0.10
1.27 (0.0500)
0.40 (0.0157)
0.25 (0.0098)
0.17 (0.0067)
SEATING
PLANE
COMPLIANT TO JEDEC STANDARDS MS-012-AA
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
Figure 58. 8-Lead Standard Small Outline Package [SOIC_N]
Narrow Body
(R-8)
Dimensions shown in millimeters and (inches)
ORDERING GUIDE
Model
Temperature Range
Package Description
8-Lead MSOP
8-Lead MSOP
Package Option
Branding
A1P
A1P
AD8622ARMZ1
AD8622ARMZ-REEL1
AD8622ARMZ-R71
AD8622ARZ1
AD8622ARZ-REEL1
AD8622ARZ-REEL71
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
RM-8
RM-8
RM-8
R-8
R-8
R-8
8-Lead MSOP
A1P
8-Lead SOIC_N
8-Lead SOIC_N
8-Lead SOIC_N
1 Z = RoHS Compliant Part.
Rev. 0 | Page 18 of 20
AD8622
NOTES
Rev. 0 | Page 19 of 20
AD8622
NOTES
©2009 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D07527-0-7/09(0)
Rev. 0 | Page 20 of 20
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