AD AD8546 18 v, micropower, cmos, rail-to-rail input/output operational amplifier Datasheet

18 V, Micropower, CMOS, Rail-to-Rail
Input/Output Operational Amplifier
AD8546
PIN CONFIGURATION
Micropower at high voltage (18 V): 18 μA typical
Single-supply operation: 2.7 V to 18 V
Dual-supply operation: ±1.35 V to ±9 V
Low input bias current: 20 pA
Gain bandwidth product: 200 kHz
Unity-gain stable
OUT A 1
–IN A 2
+IN A 3
AD8546
TOP VIEW
(Not to Scale)
V– 4
8
V+
7
OUT B
6
–IN B
5
+IN B
09585-001
FEATURES
Figure 1. 8-Lead MSOP
APPLICATIONS
Portable medical equipment
Current monitors
4 mA to 20 mA loop drivers
Buffer/level shifting
Multipole filters
Remote/wireless sensors
Low power transimpedance amplifiers
GENERAL DESCRIPTION
Table 1. Micropower Op Amps1
The AD8546 is a dual, micropower, high impedance, rail-to-rail
input/output amplifier optimized for low power and wide operating
supply voltage range applications.
Amplifier
Single
The AD8546 operates from 2.7 V up to 18 V with a typical supply
current of 18 μA. The combination of low supply current, high
input impedance, and rail-to-rail input and output makes the
AD8546 ideal for dc gain and buffering of sensor front ends or
high impedance input sources in wireless or remote sensors or
transmitters.
With its low power consumption and rail-to-rail input and
output, the AD8546 is ideally suited for a variety of batterypowered, portable applications such as ECGs, pulse monitors,
glucose meters, smoke and fire detectors, vibration monitors,
and backup battery sensors.
Dual
Quad
The AD8546 is specified over the extended industrial temperature
range of −40°C to +125°C and is available in an 8-lead MSOP.
1
5V
AD8500
ADA4505-1
AD8505
AD8541
AD8603
AD8502
ADA4505-2
AD8506
AD8542
AD8607
AD8504
ADA4505-4
AD8508
AD8544
AD8609
Supply Voltage
12 V to 16 V
36 V
AD8663
AD8667
OP281
OP295
ADA4062-2
AD8669
OP481
OP495
ADA4062-4
See www.analog.com for the latest selection of micropower op amps.
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 registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
©2011 Analog Devices, Inc. All rights reserved.
AD8546
TABLE OF CONTENTS
Features .............................................................................................. 1
Typical Performance Characteristics ..............................................7
Applications ....................................................................................... 1
Applications Information .............................................................. 17
Pin Configuration ............................................................................. 1
Input Stage ................................................................................... 17
General Description ......................................................................... 1
Output Stage................................................................................ 18
Revision History ............................................................................... 2
Rail-to-Rail Input and Output .................................................. 18
Specifications..................................................................................... 3
Resistive Load ............................................................................. 18
Electrical Characteristics—2.7 V Operation ............................ 3
Comparator Operation .............................................................. 18
Electrical Characteristics—10 V Operation ............................. 4
4 mA to 20 mA Process Control Current Loop Transmitter 19
Electrical Characteristics—18 V Operation ............................. 5
Outline Dimensions ....................................................................... 21
Absolute Maximum Ratings............................................................ 6
Ordering Guide .......................................................................... 21
Thermal Resistance ...................................................................... 6
ESD Caution .................................................................................. 6
REVISION HISTORY
1/11—Revision 0: Initial Version
Rev. 0 | Page 2 of 24
AD8546
SPECIFICATIONS
ELECTRICAL CHARACTERISTICS—2.7 V OPERATION
VSY = 2.7 V, VCM = VSY/2, TA = 25°C, unless otherwise specified.
Table 2.
Parameter
INPUT CHARACTERISTICS
Offset Voltage
Input Bias Current
Symbol
Test Conditions/Comments
VOS
VCM = 0 V to 2.7 V
VCM = 0.3 V to 2.4 V; −40°C ≤ TA ≤ +85°C
VCM = 0 V to 2.7 V; −40°C ≤ TA ≤ +85°C
VCM = 0.3 V to 2.4 V; −40°C ≤ TA ≤ +125°C
VCM = 0 V to 2.7 V; −40°C ≤ TA ≤ +125°C
Min
Typ
3
10
CINDM
CINCM
3.5
3.5
pF
pF
1
IOS
−40°C ≤ TA ≤ +125°C
CMRR
Large Signal Voltage Gain
AVO
Supply Current per Amplifier
DYNAMIC PERFORMANCE
Slew Rate
Settling Time to 0.1%
Gain Bandwidth Product
Phase Margin
Channel Separation
NOISE PERFORMANCE
Voltage Noise
Voltage Noise Density
Current Noise Density
3
4
5
4
12.5
10
2.6
20
500
2.7
ΔVOS/ΔT
RIN
IB
Input Voltage Range
Common-Mode Rejection Ratio
Offset Voltage Drift
Input Resistance
Input Capacitance
Differential Mode
Common Mode
OUTPUT CHARACTERISTICS
Output Voltage High
Output Voltage Low
Short-Circuit Current
Closed-Loop Output Impedance
POWER SUPPLY
Power Supply Rejection Ratio
Unit
mV
mV
mV
mV
mV
pA
nA
pA
pA
V
dB
dB
dB
dB
dB
dB
dB
dB
μV/°C
GΩ
−40°C ≤ TA ≤ +125°C
Input Offset Current
Max
VCM = 0 V to 2.7 V
VCM = 0.3 V to 2.4 V; −40°C ≤ TA ≤ +85°C
VCM = 0 V to 2.7 V; −40°C ≤ TA ≤ +85°C
VCM = 0.3 V to 2.4 V; −40°C ≤ TA ≤ +125°C
VCM = 0 V to 2.7 V; −40°C ≤ TA ≤ +125°C
RL = 100 kΩ; VO = 0.5 V to 2.2 V
−40°C ≤ TA ≤ +85°C
−40°C ≤ TA ≤ +125°C
VOH
VOL
ISC
ZOUT
RL = 100 kΩ to VCM; −40°C ≤ TA ≤ +125°C
RL = 100 kΩ to VCM; −40°C ≤ TA ≤ +125°C
PSRR
VSY = 2.7 V to 18 V
−40°C ≤ TA ≤ +125°C
IO = 0 mA
−40°C ≤ TA ≤ +125°C
ISY
0
60
59
57
58
49
92
75
65
75
105
2.69
10
±4
20
f = 1 kHz; AV = +1
90
70
120
18
22
33
V
mV
mA
Ω
dB
dB
μA
μA
SR
tS
GBP
ΦM
CS
RL = 1 MΩ; CL = 10 pF; AV = +1
VIN = 1 V step; RL = 100 kΩ; CL = 10 pF
RL = 1 MΩ; CL = 10 pF; AV = +1
RL = 1 MΩ; CL = 10 pF; AV = +1
f = 10 kHz; RL = 1 MΩ
38
14
170
69
105
V/ms
μs
kHz
Degrees
dB
en p-p
en
f = 0.1 Hz to 10 Hz
f = 1 kHz
f = 10 kHz
f = 1 kHz
6
60
56
0.1
μV p-p
nV/√Hz
nV/√Hz
pA/√Hz
in
Rev. 0 | Page 3 of 24
AD8546
ELECTRICAL CHARACTERISTICS—10 V OPERATION
VSY = 10 V, VCM = VSY/2, TA = 25°C, unless otherwise specified.
Table 3.
Parameter
INPUT CHARACTERISTICS
Offset Voltage
Input Bias Current
Symbol
Test Conditions/Comments
VOS
VCM = 0 V to 10 V
VCM = 0.3 V to 9.7 V; −40°C ≤ TA ≤ +85°C
VCM = 0 V to 10 V; −40°C ≤ TA ≤ +85°C
VCM = 0.3 V to 9.7 V; −40°C ≤ TA ≤ +125°C
VCM = 0 V to 10 V; −40°C ≤ TA ≤ +125°C
Min
Typ
3
10
CINDM
CINCM
3.5
3.5
pF
pF
2
IOS
−40°C ≤ TA ≤ +125°C
CMRR
Large Signal Voltage Gain
AVO
Supply Current per Amplifier
DYNAMIC PERFORMANCE
Slew Rate
Settling Time to 0.1%
Gain Bandwidth Product
Phase Margin
Channel Separation
NOISE PERFORMANCE
Voltage Noise
Voltage Noise Density
Current Noise Density
3
4.2
5
8.5
12.5
15
2.6
30
500
10
ΔVOS/ΔT
RIN
IB
Input Voltage Range
Common-Mode Rejection Ratio
Offset Voltage Drift
Input Resistance
Input Capacitance
Differential Mode
Common Mode
OUTPUT CHARACTERISTICS
Output Voltage High
Output Voltage Low
Short-Circuit Current
Closed-Loop Output Impedance
POWER SUPPLY
Power Supply Rejection Ratio
Unit
mV
mV
mV
mV
mV
pA
nA
pA
pA
V
dB
dB
dB
dB
dB
dB
μV/°C
GΩ
−40°C ≤ TA ≤ +125°C
Input Offset Current
Max
VCM = 0 V to 10 V
VCM = 0 V to 10 V; −40°C ≤ TA ≤ +85°C
VCM = 0 V to 10 V; −40°C ≤ TA ≤ +125°C
RL = 100 kΩ; VO = 0.5 V to 9.5 V
−40°C ≤ TA ≤ +85°C
−40°C ≤ TA ≤ +125°C
VOH
VOL
ISC
ZOUT
RL = 100 kΩ to VCM; −40°C ≤ TA ≤ +125°C
RL = 100 kΩ to VCM; −40°C ≤ TA ≤ +125°C
PSRR
VSY = 2.7 V to 18 V
−40°C ≤ TA ≤ +125°C
IO = 0 mA
−40°C ≤ TA ≤ +125°C
ISY
0
70
70
60
95
90
67
88
115
9.98
20
±11
15
f = 1 kHz; AV = +1
90
70
120
18
22
33
V
mV
mA
Ω
dB
dB
μA
μA
SR
tS
GBP
ΦM
CS
RL = 1 MΩ; CL = 10 pF; AV = +1
VIN = 1 V step; RL = 100 kΩ; CL = 10 pF
RL = 1 MΩ; CL = 10 pF; AV = +1
RL = 1 MΩ; CL = 10 pF; AV = +1
f = 10 kHz; RL = 1 MΩ
60
13
200
60
105
V/ms
μs
kHz
Degrees
dB
en p-p
en
f = 0.1 Hz to 10 Hz
f = 1 kHz
f = 10 kHz
f = 1 kHz
5
50
45
0.1
μV p-p
nV/√Hz
nV/√Hz
pA/√Hz
in
Rev. 0 | Page 4 of 24
AD8546
ELECTRICAL CHARACTERISTICS—18 V OPERATION
VSY = 18 V, VCM = VSY/2, TA = 25°C, unless otherwise specified.
Table 4.
Parameter
INPUT CHARACTERISTICS
Offset Voltage
Input Bias Current
Symbol
Test Conditions/Comments
VOS
VCM = 0 V to 18 V
VCM = 0.3 V to 17.7 V; −40°C ≤ TA ≤ +85°C
VCM = 0 V to 18 V; −40°C ≤ TA ≤ +85°C
VCM = 0.3 V to 17.7 V; −40°C ≤ TA ≤ +125°C
VCM = 0 V to 18 V; −40°C ≤ TA ≤ +125°C
Min
Typ
3
10
CINDM
CINCM
3.5
10.5
pF
pF
5
IOS
−40°C ≤ TA ≤ +125°C
CMRR
Large Signal Voltage Gain
AVO
Supply Current per Amplifier
DYNAMIC PERFORMANCE
Slew Rate
Settling Time to 0.1%
Gain Bandwidth Product
Phase Margin
Channel Separation
NOISE PERFORMANCE
Voltage Noise
Voltage Noise Density
Current Noise Density
3
4.5
5
11
14
20
2.9
40
500
18
ΔVOS/ΔT
RIN
IB
Input Voltage Range
Common-Mode Rejection Ratio
Offset Voltage Drift
Input Resistance
Input Capacitance
Differential Mode
Common Mode
OUTPUT CHARACTERISTICS
Output Voltage High
Output Voltage Low
Short-Circuit Current
Closed-Loop Output Impedance
POWER SUPPLY
Power Supply Rejection Ratio
Unit
mV
mV
mV
mV
mV
pA
nA
pA
pA
V
dB
dB
dB
dB
dB
dB
dB
dB
μV/°C
GΩ
−40°C ≤ TA ≤ +125°C
Input Offset Current
Max
VCM = 0 V to 18 V
VCM = 0.3 V to 17.7 V; −40°C ≤ TA ≤ +85°C
VCM = 0 V to 18 V; −40°C ≤ TA ≤ +85°C
VCM = 0.3 V to 17.7 V; −40°C ≤ TA ≤ +125°C
VCM = 0 V to 18 V; −40°C ≤ TA ≤ +125°C
RL = 100 kΩ; VO = 0.5 V to 17.5 V
−40°C ≤ TA ≤ +85°C
−40°C ≤ TA ≤ +125°C
VOH
VOL
ISC
ZOUT
RL = 100 kΩ to VCM; −40°C ≤ TA ≤ +125°C
RL = 100 kΩ to VCM; −40°C ≤ TA ≤ +125°C
PSRR
VSY = 2.7 V to 18 V
−40°C ≤ TA ≤ +125°C
IO = 0 mA
−40°C ≤ TA ≤ +125°C
ISY
0
80
77
72
65
63
88
82
73
95
100
17.97
30
±12
15
f = 1 kHz; AV = +1
90
70
120
18
22
33
V
mV
mA
Ω
dB
dB
μA
μA
SR
tS
GBP
ΦM
CS
RL = 1 MΩ; CL = 10 pF; AV = +1
VIN = 1 V step; RL = 100 kΩ; CL = 10 pF
RL = 1 MΩ; CL = 10 pF; AV = +1
RL = 1 MΩ; CL = 10 pF; AV = +1
f = 10 kHz; RL = 1 MΩ
70
12
200
60
105
V/ms
μs
kHz
Degrees
dB
en p-p
en
f = 0.1 Hz to 10 Hz
f = 1 kHz
f = 10 kHz
f = 1 kHz
5
50
45
0.1
μV p-p
nV/√Hz
nV/√Hz
pA/√Hz
in
Rev. 0 | Page 5 of 24
AD8546
ABSOLUTE MAXIMUM RATINGS
THERMAL RESISTANCE
Table 5.
Parameter
Supply Voltage
Input Voltage
Input Current1
Differential Input Voltage
Output Short-Circuit Duration
to GND
Storage Temperature Range
Operating Temperature Range
Junction Temperature Range
Lead Temperature
(Soldering, 60 sec)
1
Rating
20.5 V
(V−) − 300 mV to (V+) + 300 mV
±10 mA
±VSY
Indefinite
−65°C to +150°C
−40°C to +125°C
−65°C to +150°C
300°C
θJA is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages using a
standard 4-layer board.
Table 6. Thermal Resistance
Package Type
8-Lead MSOP (RM-8)
ESD CAUTION
The input pins have clamp diodes to the power supply pins. Limit the input
current to 10 mA or less whenever input signals exceed the power supply
rail by 0.3 V.
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 6 of 24
θJA
142
θJC
45
Unit
°C/W
AD8546
TYPICAL PERFORMANCE CHARACTERISTICS
TA = 25°C, unless otherwise noted.
40
VSY = 2.7V
VCM = VSY/2
35
NUMBER OF AMPLIFIERS
30
25
20
15
10
30
25
20
15
10
0
0
09585-002
VOS (mV)
–2.4
–2.2
–2.0
–1.8
–1.6
–1.4
–1.2
–1.0
–0.8
–0.6
–0.4
–0.2
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
5
–2.4
–2.2
–2.0
–1.8
–1.6
–1.4
–1.2
–1.0
–0.8
–0.6
–0.4
–0.2
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
5
VOS (mV)
Figure 2. Input Offset Voltage Distribution
Figure 5. Input Offset Voltage Distribution
12
TCVOS (µV/°C)
TCVOS (µV/°C)
Figure 3. Input Offset Voltage Drift Distribution
Figure 6. Input Offset Voltage Drift Distribution
3.0
3.0
VSY = 2.7V
VSY = 18V
2.5
2.0
1.5
1.5
1.0
1.0
0.5
0.5
VOS (mV)
2.0
0
–0.5
0
–0.5
–1.5
–1.5
–2.0
–2.0
–2.5
–2.5
0
0.3
0.6
0.9
1.2
1.5
1.8
2.1
2.4
VCM (V)
2.7
–3.0
0
2
4
6
8
10
12
14
16
VCM (V)
Figure 7. Input Offset Voltage vs. Common-Mode Voltage
Figure 4. Input Offset Voltage vs. Common-Mode Voltage
Rev. 0 | Page 7 of 24
18
09585-007
–1.0
–1.0
09585-004
VOS (mV)
2.5
–3.0
4.0
0
0.2
4.0
09585-003
3.6
3.8
3.4
3.0
3.2
2.4
2.6
2.8
2.2
1.6
1.8
2.0
0
1.4
0
0.8
1.0
1.2
2
0.4
0.6
2
09585-006
4
2.2
2.4
2.6
2.8
4
6
1.4
1.6
1.8
2.0
6
8
0.8
1.0
1.2
NUMBER OF AMPLIFIERS
10
8
0
0.2
NUMBER OF AMPLIFIERS
10
VSY = 18V
–40°C ≤ TA ≤ +125°C
3.4
3.6
3.8
VSY = 2.7V
–40°C ≤ TA ≤ +125°C
3.0
3.2
12
0.4
0.6
NUMBER OF AMPLIFIERS
VSY = 18V
VCM = VSY/2
35
09585-005
40
AD8546
3.0
3.0
VSY = 2.7V
–40°C ≤ TA ≤ +85°C
2.0
2.0
1.5
1.5
1.0
1.0
0.5
0.5
0
–0.5
–1.0
–0.5
–1.5
–1.5
–2.0
–2.5
–2.5
0.3
0.6
0.9
1.2
1.5
1.8
2.1
2.4
2.7
VCM (V)
–3.0
09585-008
0
2
4
6
8
10
12
14
16
18
VCM (V)
Figure 8. Input Offset Voltage vs. Common-Mode Voltage
Figure 11. Input Offset Voltage vs. Common-Mode Voltage
3.0
8.0
7.0
VSY = 2.7V
–40°C ≤ TA ≤ +125°C
2.5
0
09585-011
–1.0
–3.0
VSY = 18V
–40°C ≤ TA ≤ +125°C
6.0
2.0
5.0
1.5
4.0
1.0
3.0
2.0
1.0
0
0.5
VOS (mV)
0
–0.5
–1.0
–1.0
–2.0
–3.0
–1.5
–4.0
–2.0
–5.0
0.3
0.6
0.9
1.2
1.5
1.8
2.1
2.4
2.7
VCM (V)
09585-009
0
–7.0
–8.0
8
10
12
14
16
18
VSY = 18V
1000
100
IB+
IB–
IB (pA)
IB (pA)
6
10000
VSY = 2.7V
10
1
1
50
75
100
TEMPERATURE (°C)
125
09585-010
10
0.1
25
4
Figure 12. Input Offset Voltage vs. Common-Mode Voltage
1000
100
2
VCM (V)
Figure 9. Input Offset Voltage vs. Common-Mode Voltage
10000
0
09585-012
–6.0
–2.5
0.1
25
IB+
IB–
50
75
100
TEMPERATURE (°C)
Figure 13. Input Bias Current vs. Temperature
Figure 10. Input Bias Current vs. Temperature
Rev. 0 | Page 8 of 24
125
09585-013
VOS (mV)
0
–2.0
–3.0
VSY = 18V
–40°C ≤ TA ≤ +85°C
2.5
VOS (mV)
VOS (mV)
2.5
AD8546
4
4
VSY = 18V
3
2
2
1
1
125°C
85°C
25°C
–1
–2
–2
–3
–3
0
0.3
0.6
0.9
1.2
1.5
1.8
2.1
2.4
2.7
VCM (V)
–4
0
2
4
6
8
10
12
14
16
Figure 17. Input Bias Current vs. Common-Mode Voltage
10
10
OUTPUT VOLTAGE (VOH) TO SUPPLY RAIL (V)
Figure 14. Input Bias Current vs. Common-Mode Voltage
VSY = 2.7V
1
–40°C
+25°C
+85°C
+125°C
100m
10m
1m
0.1m
0.01m
0.001
0.01
0.1
1
LOAD CURRENT (mA)
10
100
18
VCM (V)
VSY = 18V
1
–40°C
+25°C
+85°C
+125°C
100m
10m
1m
0.1m
0.01m
0.001
09585-015
Figure 15. Output Voltage (VOH) to Supply Rail vs. Load Current
0.01
0.1
1
LOAD CURRENT (mA)
10
100
Figure 18. Output Voltage (VOH) to Supply Rail vs. Load Current
10
OUTPUT VOLTAGE (VOL) TO SUPPLY RAIL (V)
10
VSY = 2.7V
1
100m
10m
–40°C
+25°C
+85°C
+125°C
1m
0.01m
0.001
0.01
0.1
1
LOAD CURRENT (mA)
10
100
09585-016
0.1m
Figure 16. Output Voltage (VOL) to Supply Rail vs. Load Current
VSY = 18V
1
100m
10m
–40°C
+25°C
+85°C
+125°C
1m
0.1m
0.01m
0.001
0.01
0.1
1
LOAD CURRENT (mA)
10
100
Figure 19. Output Voltage (VOL) to Supply Rail vs. Load Current
Rev. 0 | Page 9 of 24
09585-019
OUTPUT VOLTAGE (VOH) TO SUPPLY RAIL (V)
125°C
85°C
25°C
–1
–4
OUTPUT VOLTAGE (VOL) TO SUPPLY RAIL (V)
0
09585-018
0
09585-017
IB (nA)
3
09585-014
IB (nA)
VSY = 2.7V
AD8546
18.000
2.700
RL = 1MΩ
RL = 1MΩ
OUTPUT VOLTAGE, VOH (V)
2.698
2.697
RL = 100kΩ
2.696
17.990
17.985
RL = 100kΩ
17.980
VSY = 2.7V
0
25
50
75
100
125
17.975
–50
TEMPERATURE (°C)
0
25
75
100
125
Figure 23. Output Voltage (VOH) vs. Temperature
6
12
VSY = 18V
VSY = 2.7V
5
4
3
RL = 100kΩ
2
RL = 100kΩ
8
6
4
2
RL = 1MΩ
RL = 1MΩ
–25
0
25
50
75
100
125
TEMPERATURE (°C)
0
–50
09585-021
0
–50
0
25
50
75
100
125
18
TEMPERATURE (°C)
Figure 21. Output Voltage (VOL) vs. Temperature
Figure 24. Output Voltage (VOL) vs. Temperature
35
35
VSY = 2.7V
VSY = 18V
30
25
25
ISY PER AMP (µA)
30
20
15
10
20
15
10
–40°C
+25°C
+85°C
+125°C
0
0.3
0.6
0.9
1.2
1.5
VCM (V)
1.8
2.1
2.4
–40°C
+25°C
+85°C
+125°C
5
2.7
09585-022
5
0
–25
09585-024
OUTPUT VOLTAGE, VOL (mV)
10
1
ISY PER AMP (µA)
50
TEMPERATURE (°C)
Figure 20. Output Voltage (VOH) vs. Temperature
OUTPUT VOLTAGE, VOL (mV)
–25
Figure 22. Supply Current per Amplifier vs. Common-Mode Voltage
0
0
3
6
9
VCM (V)
12
15
Figure 25. Supply Current per Amplifier vs. Common-Mode Voltage
Rev. 0 | Page 10 of 24
09585-023
–25
09585-020
2.695
–50
VSY = 18V
09585-025
OUTPUT VOLTAGE, VOH (V)
2.699
17.995
AD8546
60
35
30
50
VSY = 2.7V
VSY = 18V
40
ISY PER AMP (µA)
ISY PER AMP (µA)
25
20
15
10
30
20
–40°C
+25°C
5
10
+85°C
9
12
15
18
VSY (V)
0
–50
135
0
–45
–20
CL = 10pF
135
VSY = 18V
RL = 1MΩ
40
90
20
45
0
–45
–20
CL = 10pF
–40
–135
1M
100k
FREQUENCY (Hz)
–90
CL = 100pF
–60
1k
10k
–135
1M
100k
FREQUENCY (Hz)
Figure 30. Open-Loop Gain and Phase vs. Frequency
Figure 27. Open-Loop Gain and Phase vs. Frequency
60
60
VSY = 2.7V
0
40
AV = +10
AV = +1
–20
–40
0
AV = +10
AV = +1
–20
–40
1k
10k
100k
FREQUENCY (Hz)
1M
09585-028
–60
100
20
AV = +100
Figure 28. Closed-Loop Gain vs. Frequency
–60
100
1k
10k
100k
FREQUENCY (Hz)
Figure 31. Closed-Loop Gain vs. Frequency
Rev. 0 | Page 11 of 24
1M
09585-031
20
VSY = 18V
AV = +100
CLOSED-LOOP GAIN (dB)
40
125
GAIN
09585-027
10k
100
0
–90
CL = 100pF
–60
1k
OPEN-LOOP GAIN (dB)
45
PHASE (Degrees)
20
GAIN
75
60
PHASE
90
CLOSED-LOOP GAIN (dB)
OPEN-LOOP GAIN (dB)
PHASE
–40
25
50
TEMPERATURE (°C)
VSY = 2.7V
RL = 1MΩ
40
0
0
Figure 29. Supply Current per Amplifier vs. Temperature
Figure 26. Supply Current per Amplifier vs. Supply Voltage
60
–25
PHASE (Degrees)
6
09585-030
3
09585-026
0
09585-029
+125°C
0
AD8546
1000
1000
AV = +100
AV = +100
AV = +10
AV = +10
100
100
AV = +1
ZOUT (Ω)
ZOUT (Ω)
AV = +1
10
10
1k
10k
FREQUENCY (Hz)
100k
09585-032
100
1
100
Figure 32. Output Impedance vs. Frequency
140
VSY = 2.7V
VCM = 2.4V
100
60
80
60
40
40
20
20
1k
10k
100k
1M
FREQUENCY (Hz)
0
100
1k
10k
100k
Figure 33. CMRR vs. Frequency
Figure 36. CMRR vs. Frequency
100
100
VSY = 18V
80
60
60
PSRR (dB)
80
PSRR+
PSRR–
40
PSRR+
PSRR–
40
20
1k
10k
100k
FREQUENCY (Hz)
1M
Figure 34. PSRR vs. Frequency
0
100
1k
10k
100k
FREQUENCY (Hz)
Figure 37. PSRR vs. Frequency
Rev. 0 | Page 12 of 24
1M
09585-037
20
09585-034
PSRR (dB)
VSY = 2.7V
0
100
1M
FREQUENCY (Hz)
09585-036
CMRR (dB)
80
09585-033
CMRR (dB)
VSY = 18V
VCM = VSY/2
120
100
0
100
100k
Figure 35. Output Impedance vs. Frequency
140
120
1k
10k
FREQUENCY (Hz)
09585-035
VSY = 18V
VSY = 2.7V
1
AD8546
70
70
VSY = 2.7V
VIN = 10mV p-p
RL = 1MΩ
60
60
50
OVERSHOOT (%)
50
40
30
OS+
OS–
20
40
30
20
OS+
OS–
100
1000
CAPACITANCE (pF)
0
10
09585-038
100
1000
CAPACITANCE (pF)
Figure 38. Small Signal Overshoot vs. Load Capacitance
Figure 41. Small Signal Overshoot vs. Load Capacitance
VSY = ±1.35V
AV = +1
RL = 1MΩ
CL = 100pF
TIME (100µs/DIV)
09585-042
09585-039
VOLTAGE (5V/DIV)
VOLTAGE (500mV/DIV)
VSY = ±9V
AV = +1
RL = 1MΩ
CL = 100pF
TIME (100µs/DIV)
Figure 39. Large Signal Transient Response
Figure 42. Large Signal Transient Response
VSY = ±1.35V
AV = +1
RL = 1MΩ
CL = 100pF
TIME (100µs/DIV)
09585-040
VOLTAGE (5mV/DIV)
VSY = ±9V
AV = +1
RL = 1MΩ
CL = 100pF
TIME (100µs/DIV)
Figure 40. Small Signal Transient Response
Figure 43. Small Signal Transient Response
Rev. 0 | Page 13 of 24
09585-043
0
10
09585-041
10
10
VOLTAGE (5mV/DIV)
OVERSHOOT (%)
VSY = 18V
VIN = 10mV p-p
RL = 1MΩ
AD8546
INPUT
1
–1
–2
10
5
OUTPUT
OUTPUT
09585-044
0
TIME (40µs/DIV)
TIME (40µs/DIV)
Figure 44. Positive Overload Recovery
Figure 47. Positive Overload Recovery
VSY = ±1.35V
AV = –10
RL = 1MΩ
0.4
VSY = ±9V
AV = –10
RL = 1MΩ
2
OUTPUT
0
–1
INPUT VOLTAGE (V)
INPUT
0
OUTPUT
0
–5
TIME (40µs/DIV)
TIME (40µs/DIV)
Figure 45. Negative Overload Recovery
Figure 48. Negative Overload Recovery
INPUT
VOLTAGE (500mV/DIV)
VOLTAGE (500mV/DIV)
INPUT
VSY = 2.7V
RL = 100kΩ
CL = 10pF
+5mV
0
ERROR BAND
09585-048
–10
09585-045
–2
VSY = 18V
RL = 100kΩ
CL = 10pF
+5mV
0
ERROR BAND
OUTPUT
OUTPUT
–5mV
09585-046
TIME (10µs/DIV)
–5mV
Figure 46. Positive Settling Time to 0.1%
TIME (10µs/DIV)
Figure 49. Positive Settling Time to 0.1%
Rev. 0 | Page 14 of 24
09585-049
0
OUTPUT VOLTAGE (V)
1
INPUT
OUTPUT VOLTAGE (V)
0.2
INPUT VOLTAGE (V)
0
09585-047
2
INPUT VOLTAGE (V)
VSY = ±1.35V
AV = –10
RL = 1MΩ
–0.4
OUTPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT
0
–0.2
VSY = ±9V
AV = –10
RL = 1MΩ
OUTPUT VOLTAGE (V)
0
AD8546
VSY = 18V
RL = 100kΩ
CL = 10pF
VOLTAGE (500mV/DIV)
INPUT
+5mV
OUTPUT
0
ERROR BAND
+5mV
OUTPUT
TIME (10µs/DIV)
–5mV
TIME (10µs/DIV)
Figure 50. Negative Settling Time to 0.1%
Figure 53. Negative Settling Time to 0.1%
1000
1000
VSY = 18V
100
1
100
1k
10k
FREQUENCY (Hz)
100k
1M
1
10
Figure 51. Voltage Noise Density vs. Frequency
100
1k
10k
FREQUENCY (Hz)
100k
1M
Figure 54. Voltage Noise Density vs. Frequency
VSY = 18V
VOLTAGE (2µV/DIV)
TIME (2s/DIV)
09585-052
VOLTAGE (2µV/DIV)
VSY = 2.7V
TIME (2s/DIV)
Figure 52. 0.1 Hz to 10 Hz Noise
Figure 55. 0.1 Hz to 10 Hz Noise
Rev. 0 | Page 15 of 24
09585-055
10
10
09585-051
10
100
09585-054
VOLTAGE NOISE DENSITY (nV/ Hz)
VSY = 2.7V
VOLTAGE NOISE DENSITY (nV/ Hz)
0
ERROR BAND
09585-050
–5mV
INPUT
09585-053
VOLTAGE (500mV/DIV)
VSY = 2.7V
RL = 100kΩ
CL = 10pF
AD8546
20
3.0
VSY = 2.7V
VIN = 2.6V
RL = 1MΩ
AV = +1
16
OUTPUT SWING (V)
OUTPUT SWING (V)
2.5
VSY = 18V
VIN = 17.9V
RL = 1MΩ
AV = +1
18
2.0
1.5
1.0
14
12
10
8
6
4
0.5
1k
10k
100k
1M
FREQUENCY (Hz)
0
09585-056
100
10
100
Figure 56. Output Swing vs. Frequency
100
100k
1M
VSY = 18V
VIN = 0.5V rms
RL = 1MΩ
AV = +1
10
THD + N (%)
1
1
100
1k
10k
100k
FREQUENCY (Hz)
0.01
10
09585-057
0.01
10
100
Figure 57. THD + N vs. Frequency
0
1MΩ
10kΩ
–20
CHANNEL SEPARATION (dB)
–20
RL
–40
–60
VIN = 0.5V p-p
–80
10k
100k
Figure 60. THD + N vs. Frequency
0
VSY = 2.7V
RL = 1MΩ
AV = –100
1k
FREQUENCY (Hz)
09585-060
0.1
VIN = 1.5V p-p
VIN = 2.6V p-p
–100
1MΩ
VSY = 18V
RL = 1MΩ
AV = –100
10kΩ
RL
–40
VIN = 1V p-p
VIN = 5V p-p
VIN = 10V p-p
VIN = 15V p-p
VIN = 17V p-p
–60
–80
–100
–120
–140
100
1k
10k
FREQUENCY (Hz)
100k
09585-058
–120
–140
100
1k
10k
FREQUENCY (Hz)
Figure 61. Channel Separation vs. Frequency
Figure 58. Channel Separation vs. Frequency
Rev. 0 | Page 16 of 24
100k
09585-061
THD + N (%)
100
0.1
CHANNEL SEPARATION (dB)
10k
Figure 59. Output Swing vs. Frequency
VSY = 2.7V
VIN = 0.2V rms
RL = 1MΩ
AV = +1
10
1k
FREQUENCY (Hz)
09585-059
2
0
10
AD8546
APPLICATIONS INFORMATION
The AD8546 is a low input bias current, micropower CMOS
amplifier that operates over a wide supply voltage range of 2.7 V
to 18 V. The AD8546 also employs unique input and output
stages to achieve a rail-to-rail input and output range with a
very low supply current.
drain impedances contributes to the offset voltage of the amplifier. This problem is exacerbated at high temperatures due to
the decrease in the threshold voltage of the input transistors.
Refer to Figure 8, Figure 9, Figure 11, and Figure 12 for typical
performance data.
INPUT STAGE
Current Source I1 drives the PMOS transistor pair. As the input
common-mode voltage approaches the upper rail, I1 is steered
away from the PMOS differential pair through the M5 transistor.
The bias voltage, VB1, controls the point where this transfer occurs.
Figure 62 shows the simplified schematic of the AD8546. The
input stage comprises two differential transistor pairs, an NMOS
pair (M1, M2) and a PMOS pair (M3, M4). The input commonmode voltage determines which differential pair turns on and is
more active than the other.
M5 diverts the tail current into a current mirror consisting of the
M6 and M7 transistors. The output of the current mirror then
drives the NMOS transistor pair. Note that the activation of this
current mirror causes a slight increase in supply current at high
common-mode voltages (see Figure 22 and Figure 25).
The PMOS differential pair is active when the input voltage
approaches and reaches the lower supply rail. The NMOS pair
is needed for input voltages up to and including the upper
supply rail. This topology allows the amplifier to maintain a
wide dynamic input voltage range and maximize signal swing
to both supply rails.
The AD8546 achieves its high performance by using low voltage
MOS devices for its differential inputs. These low voltage MOS
devices offer excellent noise and bandwidth per unit of current.
Each differential input pair is protected by proprietary regulation
circuitry (not shown in the simplified schematic). The regulation
circuitry consists of a combination of active devices that maintain
the proper voltages across the input pairs during normal operation and passive clamping devices that protect the amplifier during
fast transients. However, these passive clamping devices begin
to forward-bias as the common-mode voltage approaches either
power supply rail. This causes an increase in the input bias
current (see Figure 14 and Figure 17).
For the majority of the input common-mode voltage range, the
PMOS differential pair is active. Differential pairs commonly
exhibit different offset voltages. The handoff from one pair to
the other creates a step-like characteristic that is visible in the
VOS vs. VCM graphs (see Figure 4 and Figure 7). This characteristic
is inherent in all rail-to-rail amplifiers that use the dual differential
pair topology. Therefore, always choose a common-mode voltage
that does not include the region of handoff from one input
differential pair to the other.
The input devices are also protected from large differential input
voltages by clamp diodes (D1 and D2). These diodes are buffered
from the inputs with two 10 kΩ resistors (R1 and R2). The differential diodes turn on whenever the differential voltage exceeds
approximately 600 mV; in this condition, the differential input
resistance drops to 20 kΩ.
Additional steps in the VOS vs. VCM curves are also visible as the
input common-mode voltage approaches the power supply rails.
These changes are a result of the load transistors (M8, M9, M14,
and M15) running out of headroom. As the load transistors are
forced into the triode region of operation, the mismatch of their
V+
VB1
I1
M5
+IN x
M3
R1
D1
–IN x
M8
M9
M10
M11
M4
M16
D2
VB2
R2
M1
OUT x
M2
M7
M6
M13
M14
M15
V–
Figure 62. Simplified Schematic
Rev. 0 | Page 17 of 24
09585-062
M17
M12
AD8546
The AD8546 features a complementary output stage consisting
of the M16 and M17 transistors (see Figure 62). These transistors
are configured in Class AB topology and are biased by the voltage
source, VB2. This topology allows the output voltage to go within
millivolts of the supply rails, achieving a rail-to-rail output swing.
The output voltage is limited by the output impedance of the
transistors, which are low RON MOS devices. The output voltage
swing is a function of the load current and can be estimated using
the output voltage to supply rail vs. load current diagrams (see
Figure 15, Figure 16, Figure 18, and Figure 19).
To avoid loading the output, use a larger feedback resistor, but
consider the effect of resistor thermal noise on the overall circuit.
R2
VIN
+VSY
R1
AD8546
VOUT
1/2
RL
–VSY
09585-064
OUTPUT STAGE
RL, EFF = RL || R2
Figure 64. Inverting Op Amp Configuration
RAIL-TO-RAIL INPUT AND OUTPUT
Noninverting Configuration
The AD8546 features rail-to-rail input and output with a supply
voltage from 2.7 V to 18 V. Figure 63 shows the input and output
waveforms of the AD8546 configured as a unity-gain buffer with
a supply voltage of ±9 V and a resistive load of 1 MΩ. With an
input voltage of ±9 V, the AD8546 allows the output to swing
very close to both rails. Additionally, it does not exhibit phase
reversal.
Figure 65 shows the AD8546 in a noninverting configuration
with a resistive load, RL, at the output. The actual load seen by
the amplifier is the parallel combination of R1 + R2 and RL.
R2
AD8546
VIN
VSY = ±9V
RL = 1MΩ
VOUT
1/2
RL
–VSY
09585-065
INPUT
OUTPUT
+VSY
R1
RL, EFF = RL || (R1 + R2)
VOLTAGE (5V/DIV)
Figure 65. Noninverting Op Amp Configuration
Figure 63. Rail-to-Rail Input and Output
RESISTIVE LOAD
The feedback resistor alters the load resistance that an amplifier
sees. It is, therefore, important to be aware of the value of the
feedback resistors selected for use with the AD8546. The AD8546
is capable of driving resistive loads down to 100 kΩ. The following
two examples, inverting and noninverting configurations, show
how the feedback resistor changes the actual load resistance seen
at the output of the amplifier.
An op amp is designed to operate in a closed-loop configuration
with feedback from its output to its inverting input. Figure 66
shows the AD8546 configured as a voltage follower with an input
voltage that is always kept at midpoint of the power supplies.
The same configuration is applied to the unused channel. A1 and
A2 indicate the placement of ammeters to measure supply current.
ISY+ refers to the current flowing from the upper supply rail to the
op amp, and ISY− refers to the current flowing from the op amp to
the lower supply rail. As expected, Figure 67 shows that in normal
operating condition, the total current flowing into the op amp is
equivalent to the total current flowing out of the op amp, where
ISY+ = ISY− = 36 μA for the dual AD8546 at VSY = 18 V.
Inverting Configuration
+VSY
A1
100kΩ
Figure 64 shows the AD8546 in an inverting configuration with a
resistive load, RL, at the output. The actual load seen by the amplifier is the parallel combination of the feedback resistor, R2, and
the load, RL. The combination of a feedback resistor of 1 kΩ and
a load of 1 MΩ results in an equivalent load resistance of 999 Ω at
the output. In this condition, the AD8546 is incapable of driving
such a heavy load; therefore, its performance degrades greatly.
Rev. 0 | Page 18 of 24
ISY+
AD8546
VOUT
1/2
100kΩ
A2
–VSY
ISY–
09585-066
TIME (200µs/DIV)
09585-063
COMPARATOR OPERATION
Figure 66. Voltage Follower Configuration
AD8546
40
The AD8546 has input devices that are protected from large differential input voltages by Diode D1 and Diode D2 (see Figure 62).
These diodes consist of substrate PNP bipolar transistors and
conduct whenever the differential input voltage exceeds approximately 600 mV; however, these diodes also allow a current path
from the input to the lower supply rail, thus resulting in an increase
in the total supply current of the system. As shown in Figure 70,
both configurations yield the same result. At 18 V of power supply,
ISY+ remains at 36 μA per dual amplifier, but ISY− increases to
140 μA in magnitude per dual amplifier.
30
25
20
15
ISY–
ISY+
10
160
5
2
4
6
8
10
VSY (V)
12
14
16
18
140
Figure 67. Supply Current vs. Supply Voltage (Voltage Follower)
In contrast to op amps, comparators are designed to work in an
open-loop configuration and to drive logic circuits. Although
op amps are different from comparators, occasionally an unused
section of a dual op amp is used as a comparator to save board
space and cost; however, this is not recommended.
ISY PER DUAL AMPLIFIER (µA)
0
09585-067
0
A1
60
40
0
0
2
4
6
8
10
12
14
16
18
VSY (V)
Note that 100 kΩ resistors are used in series with the input of
the op amp. If smaller resistor values are used, the supply current
of the system increases much more. For more information about
using op amps as comparators, see the AN-849 Application
Note, Using Op Amps as Comparators.
ISY+
AD8546
VOUT
1/2
4 mA TO 20 mA PROCESS CONTROL CURRENT
LOOP TRANSMITTER
ISY–
A 2-wire current transmitter is often used in distributed control
systems and process control applications to transmit analog signals
between sensors and process controllers. Figure 71 shows a 4 mA
to 20 mA current loop transmitter.
09585-068
A2
–VSY
Figure 68. Comparator A
The transmitter is powered directly from the control loop power
supply, and the current in the loop carries signal from 4 mA to
20 mA. Thus, 4 mA establishes the baseline current budget
within which the circuit must operate.
+VSY
A1
ISY+
100kΩ
AD8546
VOUT
1/2
A2
ISY–
–VSY
09585-069
100kΩ
ISY–
ISY+
80
Figure 70. Supply Current vs. Supply Voltage (AD8546 as a Comparator)
+VSY
100kΩ
100
20
Figure 68 and Figure 69 show the AD8546 configured as a comparator, with 100 kΩ resistors in series with the input pins. Any
unused channels are configured as buffers with the input voltage
kept at the midpoint of the power supplies.
100kΩ
120
09585-070
ISY PER DUAL AMPLIFIER (µA)
35
The AD8546 is an excellent choice due to its low supply current
of 33 μA per amplifier over temperature and supply voltage. The
current transmitter controls the current flowing in the loop, where
a zero-scale input signal is represented by 4 mA of current and a
full-scale input signal is represented by 20 mA. The transmitter
also floats from the control loop power supply, VDD, whereas
signal ground is in the receiver. The loop current is measured
at the load resistor, RL, at the receiver side.
Figure 69. Comparator B
Rev. 0 | Page 19 of 24
AD8546
With a zero-scale input, a current of VREF/RNULL flows through
R´. This creates a current flowing through the sense resistor,
ISENSE, determined by the following equation:
ISENSE, MIN = (VREF × R´)/(RNULL × RSENSE)
The AD8546 and ADR125 together consume only 160 μA
quiescent current, making 3.34 mA current available to power
additional signal conditioning circuitry or to power a bridge
circuit.
ADR125
VREF
With a full-scale input voltage, current flowing through R´ is
increased by the full-scale change in VIN/RSPAN. This creates an
increase in the current flowing through the sense resistor.
RNULL
1MΩ
1%
VOUT
C2
C3
10µF 0.1µF
VIN
GND
C4
C5
0.1µF 10µF
ISENSE, DELTA = (Full-Scale Change in VIN × R´)/(RSPAN × RSENSE)
VIN
0V TO 5V
ISENSE, MAX = ISENSE, MIN + ISENSE, DELTA
R1
68kΩ
1%
When R´ >> RSENSE, the current through the load resistor at the
receiver side is almost equivalent to ISENSE.
Figure 71 shows a design for a full-scale input voltage of 5 V. At
0 V of input, loop current is 3.5 mA, and at a full-scale input of
5 V, the loop current is 21 mA. This allows software calibration
to fine-tune the current loop to the 4 mA to 20 mA range.
RSPAN
200kΩ
1%
R2
2kΩ
1%
1/2
AD8546
Q1
R4
3.3kΩ
R3
1.2kΩ
VDD
18V
D1
C1
390pF
4mA
TO
20mA
RSENSE
100Ω
1%
NOTES
1. R1 + R2 = R´.
Figure 71. 4 mA to 20 mA Current Loop Transmitter
Rev. 0 | Page 20 of 24
RL
100Ω
09585-072
Therefore
AD8546
OUTLINE DIMENSIONS
3.20
3.00
2.80
3.20
3.00
2.80
8
1
5.15
4.90
4.65
5
4
PIN 1
IDENTIFIER
0.65 BSC
0.95
0.85
0.75
15° MAX
1.10 MAX
0.40
0.25
6°
0°
0.23
0.09
COMPLIANT TO JEDEC STANDARDS MO-187-AA
0.80
0.55
0.40
10-07-2009-B
0.15
0.05
COPLANARITY
0.10
Figure 72. 8-Lead Mini Small Outline Package [MSOP]
(RM-8)
Dimensions shown in millimeters
ORDERING GUIDE
Model 1
AD8546ARMZ
AD8546ARMZ-RL
AD8546ARMZ-R7
1
Temperature Range
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
Package Description
8-Lead Mini Small Outline Package [MSOP]
8-Lead Mini Small Outline Package [MSOP]
8-Lead Mini Small Outline Package [MSOP]
Z = RoHS Compliant Part.
Rev. 0 | Page 21 of 24
Package Option
RM-8
RM-8
RM-8
Branding
A2V
A2V
A2V
AD8546
NOTES
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AD8546
NOTES
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AD8546
NOTES
©2011 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D09585-0-1/11(0)
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