AD AD8601 Precision cmos single supply rail-to-rail input/output wideband operational amplifier Datasheet

a
Precision CMOS Single Supply
Rail-to-Rail Input/Output Wideband
Operational Amplifiers
AD8601/AD8602
FEATURES
Low Offset Voltage: 500 ␮V Max
Single Supply Operation: 2.7 V to 6 V
Low Supply Current: 750 ␮A/Amplifier
Wide Bandwidth: 8 MHz
Slew Rate: 5 V/␮s
Low Distortion
No Phase Reversal
Low Input Currents
Unity Gain Stable
APPLICATIONS
Barcode Scanners
Battery-Powered Instrumentation
Multipole Filters
Sensors
Current Sensing
ASIC Input or Output Amplifier
Audio
GENERAL DESCRIPTION
The AD8601 and AD8602 are single and dual rail-to-rail input
and output single supply amplifiers featuring very low offset voltage
and wide signal bandwidth. These amplifiers use a new, patented
trimming technique that achieves superior performance without
laser trimming. All are fully specified to operate from 3 V to 5 V
single supply.
The combination of low offsets, very low input bias currents, and
high speed make these amplifiers useful in a wide variety of applications. Filters, integrators, diode amplifiers, shunt current sensors,
and high impedance sensors all benefit from the combination of
performance features. Audio and other ac applications benefit from
the wide bandwidth and low distortion. For the most cost-sensitive
applications the D grades offer this ac performance with lower dc
precision at a lower price point.
Applications for these amplifiers include audio amplification for
portable devices, portable phone headsets, bar code scanners,
portable instruments, and multipole filters.
FUNCTIONAL BLOCK DIAGRAMS
5-Lead SOT-23
(RT Suffix)
5 V+
OUT A 1
Vⴚ 2
AD8601
4 ⴚIN
+IN 3
8-Lead ␮SOIC
(RM Suffix)
OUT A
ⴚIN A
ⴙIN A
Vⴚ
1
V+
OUT B
ⴚIN B
+IN B
8
AD8602
4
5
8-Lead SOIC
(R Suffix)
OUT A 1
ⴚIN A 2
+IN A 3
Vⴚ 4
8 V+
AD8602
7 OUT B
6 ⴚIN B
5 +IN B
The ability to swing rail-to-rail at both the input and output
enables designers to buffer CMOS ADCs, DACs, ASICs, and
other wide output swing devices in single supply systems.
The AD8601 and AD8602 are specified over the extended industrial
(–40°C to +125°C) temperature range. The AD8601, single, is available in the tiny 5-lead SOT-23 package. The AD8602, dual, is available in 8-lead MSOP and narrow SOIC surface-mount packages.
SOT and µSOIC versions are available in tape and reel only.
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
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 2000
AD8601/AD8602–SPECIFICATIONS
ELECTRICAL CHARACTERISTICS (V = 3 V, V
S
CM
= VS /2, TA = 25ⴗC unless otherwise noted)
A Grade
Min Typ Max
Parameter
Symbol
Conditions
INPUT CHARACTERISTICS
Offset Voltage
VOS
0 V ≤ VCM ≤ 1.3 V
–40°C ≤ TA ≤ +85°C
–40°C ≤ TA ≤ +125°C
0 V ≤ VCM ≤ 3 V1
–40°C ≤ TA ≤ +85°C
–40°C ≤ TA ≤ +125°C
Input Bias Current
Input Offset Current
IB
IOS
Input Voltage Range
Common-Mode Rejection Ratio
Large Signal Voltage Gain
CMRR
AVO
Offset Voltage Drift
∆VOS /∆T
OUTPUT CHARACTERISTICS
Output Voltage High
VOH
Output Voltage Low
VOL
Output Current
Closed-Loop Output Impedance
IOUT
ZOUT
80
350
0.2
–40°C ≤ TA ≤ +85°C
–40°C ≤ TA ≤ +125°C
0.1
–40°C ≤ TA ≤ +85°C
–40°C ≤ TA ≤ +125°C
VCM = 0 V to 3 V
VO = 0.5 V to 2.5 V
RL = 2 kΩ , VCM = 0 V
IL = 1.0 mA
–40°C ≤ TA ≤ +125°C
IL = 1.0 mA
–40°C ≤ TA ≤ +125°C
f = 1 MHz, AV = 1
0
68
30
500
700
1,100
750
1,800
2,100
60
100
1,000
30
50
500
3
83
100
2
D Grade
Min Typ Max
65
µV
µV
µV
µV
µV
µV
pA
pA
pA
pA
pA
pA
V
dB
60
2
V/mV
µV/°C
0.2
0.1
0
52
20
Unit
6,000
7,000
7,000
6,000
7,000
7,000
200
200
1,000
100
100
500
3
2.92 2.96
2.88
20
35
50
± 30
12
2.92 2.96
2.88
20
35
50
± 30
12
V
V
mV
mV
mA
Ω
67
56
dB
µA
µA
POWER SUPPLY
Power Supply Rejection Ratio
Supply Current/Amplifier
PSRR
ISY
VS = 2.7 V to 5.5 V
VO = 0 V
–40°C ≤ TA ≤ +125°C
DYNAMIC PERFORMANCE
Slew Rate
Settling Time
Gain Bandwidth Product
Phase Margin
SR
tS
GBP
Φo
RL = 2 kΩ
To 0.01%
5.2
<0.5
8.2
50
5.2
<0.5
8.2
50
V/µs
µs
MHz
Degrees
en
en
in
f = 1 kHz
f = 10 kHz
33
18
0.05
33
18
0.05
nV/√Hz
nV/√Hz
pA/√Hz
NOISE PERFORMANCE
Voltage Noise Density
Current Noise Density
80
680
1,000
1,300
72
680
1,000
1,300
NOTES
1
For VCM between 1.3 V and 1.8 V, V OS may exceed specified value.
Specifications subject to change without notice.
–2–
REV. 0
AD8601/AD8602
ELECTRICAL CHARACTERISTICS (V = 5.0 V, V
S
CM
= VS /2, TA = 25ⴗC unless otherwise noted)
A Grade
Min Typ Max
Parameter
Symbol
Conditions
INPUT CHARACTERISTICS
Offset Voltage
VOS
0 V ≤ VCM ≤ 5 V
–40°C ≤ TA ≤ +125°C
Input Bias Current
Input Offset Current
IB
IOS
Input Voltage Range
Common-Mode Rejection Ratio
Large Signal Voltage Gain
CMRR
AVO
Offset Voltage Drift
∆VOS /∆T
OUTPUT CHARACTERISTICS
Output Voltage High
VOH
Output Voltage Low
VOL
Output Current
Closed-Loop Output Impedance
IOUT
ZOUT
80
0.2
–40°C ≤ TA ≤ +85°C
–40°C ≤ TA ≤ +125°C
0.1
–40°C ≤ TA ≤ +85°C
–40°C ≤ TA ≤ +125°C
VCM = 0 V to 5 V
VO = 0.5 V to 4.5 V
RL = 2 kΩ, VCM = 0 V
0
74
30
500
1,300
60
100
1,000
30
50
500
5
89
100
D Grade
Min Typ Max
f = 1 MHz, AV = 1
2
µV/°C
0.1
2
IL = 1.0 mA
IL = 10 mA
–40°C ≤ TA ≤ +125°C
IL = 1.0 mA
IL = 10 mA
–40°C ≤ TA ≤ +125°C
67
60
µV
µV
pA
pA
pA
pA
pA
pA
V
dB
V/mV
0.2
0
56
20
Unit
6,000
7,000
200
200
1,000
100
100
500
5
4.925 4.975
4.7 4.77
4.6
15
30
125 175
250
± 50
10
4.925 4.975
4.7 4.77
4.6
15
30
125 175
250
± 50
10
V
V
V
mV
mV
mV
mA
Ω
67
56
dB
µA
µA
POWER SUPPLY
Power Supply Rejection Ratio
Supply Current/Amplifier
PSRR
ISY
VS = 2.7 V to 5.5 V
VO = 0 V
–40°C ≤ TA ≤ +125°C
DYNAMIC PERFORMANCE
Slew Rate
Settling Time
Full Power Bandwidth
Gain Bandwidth Product
Phase Margin
SR
tS
BWp
GBP
Φo
RL = 2 kΩ
To 0.01%
< 1% Distortion
6
< 1.0
360
8.4
55
6
< 1.0
360
8.4
55
V/µs
µs
kHz
MHz
Degrees
en
en
in
f = 1 kHz
f = 10 kHz
f = 1 kHz
33
18
0.05
33
18
0.05
nV/√Hz
nV/√Hz
pA/√Hz
NOISE PERFORMANCE
Voltage Noise Density
Current Noise Density
Specifications subject to change without notice.
REV. 0
–3–
80
750
1,200
1,500
72
750
1,200
1,500
AD8601/AD8602
ABSOLUTE MAXIMUM RATINGS*
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 V
Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GND to VS
Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . ± 6 V
Storage Temperature Range
R, RM, RT Packages . . . . . . . . . . . . . . . . –65°C to +150°C
Operating Temperature Range
AD8601/AD8602 . . . . . . . . . . . . . . . . . . . –40°C to +125°C
Junction Temperature Range
R, RM, RT Packages . . . . . . . . . . . . . . . . –65°C to +150°C
Lead Temperature Range (Soldering, 60 sec) . . . . . . . . 300°C
ESD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 kV HBM
Package Type
␪JA*
␪JC
Unit
5-Lead SOT-23 (RT)
8-Lead SOIC (R)
8-Lead MSOP (RM)
230
158
210
92
43
45
°C/W
°C/W
°C/W
*θJA is specified for worst-case conditions, i.e., θJA is specified for device in
socket for PDIP packages; θJA is specified for device soldered onto a circuit
board for surface mount packages.
*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 listed in the operational sections
of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ORDERING GUIDE
Model
Temperature
Range
Package
Description
Package
Option
Branding
Information
AD8601ART
AD8601DRT
AD8602AR
AD8602DR
AD8602ARM
AD8602DRM
–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
5-Lead SOT-23
5-Lead SOT-23
8-Lead SOIC
8-Lead SOIC
8-Lead MSOP
8-Lead MSOP
RT-5
RT-5
SO-8
SO-8
RM-8
RM-8
AAA
AAD
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection. Although
the AD8601/AD8602 features proprietary ESD protection circuitry, permanent damage may occur
on devices subjected to high-energy electrostatic discharges. Therefore, proper ESD precautions are
recommended to avoid performance degradation or loss of functionality.
–4–
ABA
ABD
WARNING!
ESD SENSITIVE DEVICE
REV. 0
Typical Performance Characteristics– AD8601/AD8602
60
3,000
50
QUANTITY – Amplifiers
2,500
QUANTITY – Amplifiers
VS = 5V
TA = 25ⴗC TO 85ⴗC
VS = 3V
TA = 25ⴗC
VCM = 0V TO 3V
2,000
1,500
1,000
0
ⴚ1.0
0
ⴚ0.8 ⴚ0.6 ⴚ0.4 ⴚ0.2
0.2
0.4
0.6
INPUT OFFSET VOLTAGE – mV
0
1.0
1.5
VS = 5V
TA = 25ⴗC
VCM = 0V TO 5V
2
3
4
5
6
TCVOS – ␮V/ⴗC
7
8
9
10
VS = 3V
TA = 25ⴗC
1.0
INPUT OFFSET VOLTAGE – mV
2,500
1
TPC 4. Input Offset Voltage Drift Distribution
3,000
QUANTITY – Amplifiers
20
0
0.8
TPC 1. Input Offset Voltage Distribution
2,000
1,500
1,000
500
0.5
0
ⴚ0.5
ⴚ1.0
ⴚ1.5
0
ⴚ1.0
0
ⴚ0.8 ⴚ0.6 ⴚ0.4 ⴚ0.2
0.2
0.4
0.6
INPUT OFFSET VOLTAGE – mV
ⴚ2.0
0.8
1.0
0
1.0
1.5
2.0
COMMON-MODE VOLTAGE – V
0.5
2.5
3.0
TPC 5. Input Offset Voltage vs. Common-Mode Voltage
TPC 2. Input Offset Voltage Distribution
1.5
60
VS = 3V
TA = 25ⴗC TO 85ⴗC
VS = 5V
TA = 25ⴗC
1.0
INPUT OFFSET VOLTAGE – mV
50
QUANTITY – Amplifiers
30
10
500
40
30
20
10
0.5
0
ⴚ0.5
ⴚ1.0
ⴚ1.5
ⴚ2.0
0
0
1
2
3
4
5
6
TCVOS – ␮V/ⴗC
7
8
9
10
0
1
2
3
COMMON-MODE VOLTAGE – V
4
5
TPC 6. Input Offset Voltage vs. Common-Mode Voltage
TPC 3. Input Offset Voltage Drift Distribution
REV. 0
40
–5–
AD8601/AD8602
300
30
VS = 3V
VS = 3V
INPUT OFFSET CURRENT – pA
INPUT BIAS CURRENT – pA
250
200
150
100
50
25
20
15
10
5
0
ⴚ40 ⴚ25 ⴚ10
5
20
35
50
65
TEMPERATURE – ⴗC
80
95
110
0
ⴚ40 ⴚ25 ⴚ10
125
TPC 7. Input Bias Current vs. Temperature
80
95
110
125
30
VS = 5V
VS = 5V
INPUT OFFSET CURRENT – pA
250
INPUT BIAS CURRENT – pA
20
35
50
65
TEMPERATURE – ⴗC
TPC 10. Input Offset Current vs. Temperature
300
200
150
100
50
25
20
15
10
5
0
ⴚ40 ⴚ25 ⴚ10
5
20
35
50
65
TEMPERATURE – ⴗC
80
95
110
0
ⴚ40 ⴚ25 ⴚ10
125
TPC 8. Input Bias Current vs. Temperature
5
20
35
50
65
TEMPERATURE – ⴗC
80
95
110
125
TPC 11. Input Offset Current vs. Temperature
5
10k
VS = 2.7V
TA = 25ⴗC
VS = 5V
TA = 25ⴗC
4
1k
OUTPUT VOLTAGE – mV
INPUT BIAS CURRENT – pA
5
3
2
1
100
SOURCE
SINK
10
1
0
0
0.5
1.0
2.0
2.5
3.0
3.5
4.0
1.5
COMMON-MODE VOLTAGE – V
4.5
0.1
0.001
5.0
TPC 9. Input Bias Current vs. Common-Mode Voltage
0.01
0.1
1
LOAD CURRENT – mA
10
100
TPC 12. Output Voltage to Supply Rail vs. Load Current
–6–
REV. 0
AD8601/AD8602
10k
35
VS = 5V
TA = 25ⴗC
VS = 2.7V
30
OUTPUT VOLTAGE – mV
OUTPUT VOLTAGE – mV
1k
SOURCE
100
SINK
10
25
VOL @ 1mA LOAD
20
15
10
1
5
0.1
0.001
0.1
1
LOAD CURRENT – mA
0.01
10
0
ⴚ40 ⴚ25 ⴚ10
100
TPC 13. Output Voltage to Supply Rail vs. Load Current
20
35
50
65
TEMPERATURE – ⴗC
80
95
110
125
TPC 16. Output Voltage Swing vs. Temperature
5.1
2.67
VS = 5V
VS = 2.7V
5.0
2.66
OUTPUT VOLTAGE – V
VOH @ 1mA LOAD
OUTPUT VOLTAGE – V
5
4.9
4.8
VOH @ 10mA LOAD
4.7
2.65
VOH @ 1mA LOAD
2.64
2.63
4.6
4.5
ⴚ40 ⴚ25 ⴚ10
5
20
35
50
65
TEMPERATURE – ⴗC
80
95
110
2.62
ⴚ40 ⴚ25 ⴚ10
125
TPC 14. Output Voltage Swing vs. Temperature
5
20
35
50
65
TEMPERATURE – ⴗC
80
95
110
125
TPC 17. Output Voltage Swing vs. Temperature
250
VS = 3V
RL = NO LOAD
TA = 25ⴗC
VS = 5V
150
VOL @ 10mA LOAD
100
60
45
40
90
20
135
0
180
PHASE SHIFT – Degrees
80
GAIN – dB
OUTPUT VOLTAGE – mV
200
50
VOL @ 1mA LOAD
0
ⴚ40 ⴚ25 ⴚ10
5
20
35
50
65
TEMPERATURE – ⴗC
80
95
110
125
1k
TPC 15. Output Voltage Swing vs. Temperature
REV. 0
10k
100k
1M
FREQUENCY – Hz
10M
100M
TPC 18. Open-Loop Gain and Phase vs. Frequency
–7–
AD8601/AD8602
3.0
VS = 5V
RL = NO LOAD
TA = 25ⴗC
2.5
45
40
90
20
135
0
180
OUTPUT SWING – V p-p
60
PHASE SHIFT – Degrees
GAIN – dB
80
2.0
VS = 2.7V
VIN = 2.6V p-p
RL = 2k⍀
TA = 25ⴗC
AV = 1
1.5
1.0
0.5
1k
10k
100k
1M
FREQUENCY – Hz
10M
0
1k
100M
10k
100k
FREQUENCY – Hz
1M
10M
TPC 22. Closed-Loop Output Voltage Swing vs. Frequency
TPC 19. Open-Loop Gain and Phase vs. Frequency
6
CLOSED-LOOP GAIN – dB
40
5
AV = 100
OUTPUT SWING – V p-p
VS = 3V
TA = 25ⴗC
AV = 10
20
AV = 1
0
4
3
VS = 5V
VIN = 4.9V p-p
RL = 2k⍀
TA = 25ⴗC
AV = 1
2
1
1k
10k
100k
1M
FREQUENCY – Hz
10M
0
1k
100M
10k
100k
FREQUENCY – Hz
10M
1M
TPC 23. Closed-Loop Output Voltage Swing vs. Frequency
TPC 20. Closed-Loop Gain vs. Frequency
200
CLOSED-LOOP GAIN – dB
40
180
AV = 100
AV = 10
20
AV = 1
0
VS = 3V
TA = 25ⴗC
160
OUTPUT IMPEDANCE – ⍀
VS = 5V
TA = 25ⴗC
140
AV = 100
120
100
AV = 10
80
AV = 1
60
40
20
1k
10k
100k
1M
FREQUENCY – Hz
10M
0
100
100M
1k
10k
100k
FREQUENCY – Hz
1M
10M
TPC 24. Output Impedance vs. Frequency
TPC 21. Closed-Loop Gain vs. Frequency
–8–
REV. 0
AD8601/AD8602
200
OUTPUT IMPEDANCE – ⍀
160
140
120
AV = 100
100
AV = 10
80
AV = 1
60
40
0
100
1k
10k
100k
FREQUENCY – Hz
1M
100
80
60
40
20
0
ⴚ40
100
10M
TPC 25. Output Impedance vs. Frequency
160
70
VS = 3V
140 T = 25ⴗC
A
60
120
100
80
60
40
20
0
ⴚ20
ⴚ40
1k
10k
100k
FREQUENCY – Hz
1M
10M
50
ⴚOS
40
30
+OS
20
10
100
CAPACITANCE – pF
1k
TPC 29. Small Signal Overshoot vs. Load Capacitance
70
160
VS = 5V
TA = 25ⴗC
140
60
SMALL SIGNAL OVERSHOOT – %
120
100
80
60
40
20
0
ⴚ20
VS = 5V
RL =
TA = 25ⴗC
50
40
30
20
ⴚOS
10
+OS
1k
10k
100k
FREQUENCY – Hz
1M
0
10
10M 20M
TPC 27. Common-Mode Rejection Ratio vs. Frequency
REV. 0
1M
VS = 2.7V
RL =
TA = 25ⴗC
0
10
10M 20M
TPC 26. Common-Mode Rejection Ratio vs. Frequency
ⴚ40
10k
100k
FREQUENCY – Hz
1k
TPC 28. Power Supply Rejection Ratio vs. Frequency
SMALL SIGNAL OVERSHOOT – %
COMMON-MODE REJECTION – dB
120
ⴚ20
20
COMMON-MODE REJECTION – dB
VS = 5V
TA = 25ⴗC
140
POWER SUPPLY REJECTION – dB
180
160
VS = 5V
TA = 25ⴗC
100
CAPACITANCE – pF
1k
TPC 30. Small Signal Overshoot vs. Load Capacitance
–9–
AD8601/AD8602
0.1
VS = 5V
TA = 25ⴗC
VS = 5V
RL = 10k⍀
0.01
0.8
0.6
RL = 600⍀
RL = 2k⍀
G=1
RL = 10k⍀
0.001
0.4
0.2
5
20
35
50
65
TEMPERATURE – ⴗC
80
95
110
0.0001
125
20
100
1k
FREQUENCY – Hz
10k
20k
TPC 34. Total Harmonic Distortion + Noise vs. Frequency
TPC 31. Supply Current per Amplifier vs. Temperature
1.0
64
VS = 3V
VOLTAGE NOISE DENSITY – nV/ Hz
SUPPLY CURRENT PER AMPLIFIER – mA
RL = 2k⍀
G = 10
0
ⴚ40 ⴚ25 ⴚ10
0.8
0.6
0.4
0.2
VS = 2.7V
TA = 25ⴗC
56
48
40
32
24
16
8
0
ⴚ40 ⴚ25 ⴚ10
5
20
35
50
65
TEMPERATURE – ⴗC
80
95
110
0
125
208
0.7
182
VOLTAGE NOISE DENSITY – nV/ Hz
0.8
0.6
0.5
0.4
0.3
0.2
0.1
0
0
5
10
15
FREQUENCY – kHz
20
25
TPC 35. Voltage Noise Density vs. Frequency
TPC 32. Supply Current per Amplifier vs. Temperature
SUPPLY CURRENT PER AMPLIFIER – mA
RL = 600⍀
1.0
THD + N – %
SUPPLY CURRENT PER AMPLIFIER – mA
1.2
VS = 2.7V
TA = 25ⴗC
156
130
104
78
52
26
0
1
2
3
4
SUPPLY VOLTAGE – V
5
0
6
TPC 33. Supply Current per Amplifier vs. Supply Voltage
0
0.5
1.0
1.
FREQUENCY – 5kHz
2.0
2.5
TPC 36. Voltage Noise Density vs. Frequency
–10–
REV. 0
AD8601/AD8602
208
VOLTAGE NOISE DENSITY – nV/ Hz
VS = 5V
TA = 25ⴗC
VS = 5V
TA = 25ⴗC
182
VOLTAGE – 2.5␮V/DIV
156
130
104
78
52
26
0
0
0.5
1.0
1.5
FREQUENCY – kHz
2.0
2.5
TIME – 1s/DIV
TPC 37. Voltage Noise Density vs. Frequency
TPC 40. 0.1 Hz to 10 Hz Input Voltage Noise
VS = 5V
RL = 10k⍀
CL = 100pF
TA = 25ⴗC
VS = 5V
TA = 25ⴗC
56
48
VOLTAGE – 50mV/DIV
VOLTAGE NOISE DENSITY – nV/ Hz
64
40
32
24
16
8
0
0
5
10
15
FREQUENCY – kHz
20
25
TIME – 200ns/DIV
TPC 41. Small Signal Transient Response
TPC 38. Voltage Noise Density vs. Frequency
VS = 5V
TA = 25ⴗC
VOLTAGE – 2.5␮V/DIV
VOLTAGE – 2.5␮V/DIV
VS = 2.7V
TA = 25ⴗC
TIME – 1s/DIV
TIME – 1s/DIV
TPC 42. Small Signal Transient Response
TPC 39. 0.1 Hz to 10 Hz Input Voltage Noise
REV. 0
–11–
VS = 5V
RL = 10k⍀
CL = 200pF
AV = 1
TA = 25ⴗC
VIN
VOLTAGE – 1V/DIV
VOLTAGE – 1.0V/DIV
AD8601/AD8602
VOUT
TIME – 400ns/DIV
TIME – 2.0␮s/DIV
TPC 43. Large Signal Transient Response
TPC 46. No Phase Reversal
VS = 2.7V
RL = 10k⍀
CL = 200pF
AV = 1
TA = 25ⴗC
VS = 5V
RL = 10k⍀
VO = 2V p-p
TA = 25ⴗC
VOLTAGE – V
VOLTAGE – 500mV/DIV
VS = 5V
RL = 10k⍀
AV = 1
TA = 25ⴗC
VIN
+0.1%
ERROR
VOUT
ⴚ0.1%
ERROR
VIN TRACE – 0.5V/DIV
VOUT TRACE – 10mV/DIV
TIME – 100ns/DIV
TIME – 400ns/DIV
TPC 44. Large Signal Transient Response
TPC 47. Settling Time
2.0
1.5
VS = 2.7V
TA = 25ⴗC
1.0
VIN
OUTPUT SWING – V
VOLTAGE – 1V/DIV
VS = 2.7V
RL = 10k⍀
AV = 1
TA = 25ⴗC
VOUT
0.1%
0.01%
0.5
0
ⴚ0.5
0.1%
ⴚ1.0
0.01%
ⴚ1.5
ⴚ2.0
300
TIME – 2.0␮s/DIV
TPC 45. No Phase Reversal
350
400
450
500
SETTLING TIME – ns
550
600
TPC 48. Output Swing vs. Settling Time
–12–
REV. 0
AD8601/AD8602
for single supply and low voltage applications. This rail-to-rail
input range is achieved by using two input differential pairs, one
NMOS and one PMOS, placed in parallel. The NMOS pair is
active at the upper end of the common-mode voltage range, and
the PMOS pair is active at the lower end of the common-mode
range.
VS = 5V
TA = 25ⴗC
4
OUTPUT SWING – V
3
2
1
0.1%
0.01%
0
0.1%
ⴚ1
0.01%
ⴚ2
ⴚ3
ⴚ4
ⴚ5
0
200
400
600
SETTLING TIME – ns
800
1,000
TPC 49. Output Swing vs. Settling Time
THEORY OF OPERATION
The AD8601/AD8602 family of amplifiers are rail-to-rail input and
output precision CMOS amplifiers specified from 2.7 V to 5.0 V of
power supply voltage. These amplifiers use Analog Devices’ proprietary technology called DigiTrim™ to achieve a higher degree of
precision than available from most CMOS amplifiers. DigiTrim
technology is a method of trimming the offset voltage of the
amplifier after it has already been assembled. The advantage in
post-package trimming lies in the fact that it corrects any offset
voltages due to the mechanical stresses of assembly. This technology is scalable and utilized with every package option, including
SOT23-5, providing lower offset voltages than previously achieved in
these small packages.
The NMOS and PMOS input stage are separately trimmed using
DigiTrim to minimize the offset voltage in both differential pairs.
Both NMOS and PMOS input differential pairs are active in a
500 mV transition region, when the input common-mode voltage
is between approximately 1.5 V and 1 V below the positive supply
voltage. Input offset voltage will shift slightly in this transition
region, as shown in Figures 5 and 6. Common-mode rejection
ratio will also be slightly lower when the input common-mode
voltage is within this transition band. Compared to the Burr
Brown OPA2340 rail-to-rail input amplifier, shown in Figure 1,
the AD860x, shown in Figure 2, exhibits lower offset voltage shift
across the entire input common-mode range, including the transition region.
0.7
0.4
0.1
VOS – mV
5
The DigiTrim process is done at the factory and does not add
additional pins to the amplifier. All AD860x amplifiers are available in standard op amp pinouts, making DigiTrim completely
transparent to the user. The AD860x can be used in any precision op amp application.
The open-loop gain of the AD860x is 100 dB, typical, with a load
of 2 kΩ. Because of the rail-to-rail output configuration, the gain
of the output stage, and thus the open-loop gain of the amplifier,
is dependent on the load resistance. Open-loop gain will decrease
with smaller load resistances. Again, this is a characteristic inherent to all rail-to-rail output amplifiers.
ⴚ0.5
ⴚ0.8
ⴚ1.1
ⴚ1.4
0
1
2
3
4
5
VCM – V
Figure 1. Burr Brown OPA2340UR Input Offset Voltage
vs. Common-Mode Voltage, 24 SOIC Units @ 25 °C
0.7
0.4
0.1
VOS – mV
The input stage of the amplifier is a true rail-to-rail architecture,
allowing the input common-mode voltage range of the op amp to
extend to both positive and negative supply rails. The voltage swing
of the output stage is also rail-to-rail and is achieved by using an
NMOS and PMOS transistor pair connected in a common-source
configuration. The maximum output voltage swing is proportional
to the output current, and larger currents will limit how close the
output voltage can get to the supply rail. This is a characteristic of
all rail-to-rail output amplifiers. With 1 mA of output current, the
output voltage can reach within 20 mV of the positive rail and
15 mV of the negative rail.
ⴚ0.2
ⴚ0.2
ⴚ0.5
ⴚ0.8
ⴚ1.1
Rail-to-Rail Input Stage
ⴚ1.4
The input common-mode voltage range of the AD860x extends
to both positive and negative supply voltages. This maximizes
the usable voltage range of the amplifier, an important feature
1
2
3
4
VCM – V
Figure 2. AD8602AR Input Offset Voltage vs.
Common-Mode Voltage, 300 SOIC Units @ 25 °C
DigiTrim is a trademark of Analog Devices.
REV. 0
0
–13–
5
AD8601/AD8602
Input Overvoltage Protection
10pF
(OPTIONAL)
As with any semiconductor device, if a condition could exist for
the input voltage to exceed the power supply, the device’s input
overvoltage characteristic must be considered. Excess input voltage
will energize internal PN junctions in the AD860x, allowing
current to flow from the input to the supplies.
This input current will not damage the amplifier provided it is
limited to 5 mA or less. This can be ensured by placing a resistor
in series with the input. For example, if the input voltage could
exceed the supply by 5 V, the series resistor should be at least
(5 V/5 mA) = 1 kΩ. With the input voltage within the supply
rails, a minimal amount of current is drawn into the inputs
which, in turn, causes a negligible voltage drop across the series
resistor. Thus, adding the series resistor will not adversely affect
circuit performance.
Overdrive Recovery
Overdrive recovery is defined as the time it takes the output of an
amplifier to come off the supply rail when recovering from an overload signal. This is tested by placing the amplifier in a closed-loop
gain of 10 with an input square wave of 2 V peak-to-peak while the
amplifier is powered from either 5 V or 3 V.
4.7m⍀
VOUT
4.7V/␮A
D1
AD8601
Figure 3. Amplifier Photdiode Circuit
High- and Low-Side Precision Current Monitoring
Because of its low input bias current and low offset voltage, the
AD860x can be used for precision current monitoring. The true
rail-to-rail input feature of the AD860x allows the amplifier to
monitor current on either high-side or low-side. Using both
amplifiers in an AD8602 provides a simple method for monitoring
both current supply and return paths for load or fault detection.
Figure 4 and 54 demonstrate both circuits.
3V
R2
2.49k⍀
MONITOR
OUTPUT
The AD860x has excellent recovery time from overload conditions.
The output recovers from the positive supply rail within 200 ns at all
supply voltages. Recovery from the negative rail is within 500 ns
at 5 V supply, decreasing to within 350 ns when the device is
powered from 2.7 V.
Q1
2N3905
3V
R1
100⍀
1/2 AD8602
RETURN TO
GROUND
Power-On Time
RSENSE
0.1⍀
Power-on time is important in portable applications, where the
supply voltage to the amplifier may be toggled to shut down the
device to improve battery life. Fast power-up behavior ensures
the output of the amplifier will quickly settle to its final voltage,
thus improving the power-up speed of the entire system. Once
the supply voltage reaches a minimum of 2.5 V, the AD860x
will settle to a valid output within 1 µs. This turn-on response
time is faster than many other precision amplifiers, which can
take tens or hundreds of microseconds for their output to settle.
Figure 4. A Low-Side Current Monitor
RSENSE
0.1⍀
0.1␮F
R1
100⍀
1/2
AD8602
The CMOS rail-to-rail input structure of the AD860x allows
these amplifiers to have very low input bias currents, typically
0.2 pA. This allows the AD860x to be used in any application
that has a high source impedance or must use large value resistances
around the amplifier. For example, the photodiode amplifier circuit
shown in Figure 3 requires a low input bias current op amp to
reduce output voltage error. The AD8601 minimizes offset errors
due to its low input bias current and low offset voltage.
BW =
1
2π(4.7 MΩ)C F
Q1
2N3904
MONITOR
OUTPUT
R2
2.49k⍀
Figure 5. A High-Side Current Monitor
Voltage drop is created across the 0.1 Ω resistor that is proportional to the load current. This voltage appears at the inverting
input of the amplifier due to the feedback correction around the
op amp. This creates a current through R1 which, in turn, pulls
current through R2. For the low side monitor, the monitor
output voltage is given by:
R

Monitor Output = R2 ×  SENSE  × I L
 R1 
(1)
Using a 10 pF feedback capacitor limits the bandwidth to approximately 3.3 kHz.
V+
3V
Using the AD8602 in High Source Impedance Applications
The current through the photodiode is proportional to the incident
light power on its surface. The 4.7 MΩ resistor converts this
current into a voltage, with the output of the AD8601 increasing at 4.7 V/µA. The feedback capacitor reduces excess noise at
higher frequencies by limiting the bandwidth of the circuit to:
IL
3V
(2)
For the high-side monitor, the monitor output voltage is:
–14–
REV. 0
AD8601/AD8602
R

Monitor Output = V + ( −R2) ×  SENSE  × I L
 R1 
PC100 Compliance for Computer Audio Applications
(3)
Using the components shown, the monitor output transfer function
is 2.5 V/A.
Using the AD8601 in Single Supply Mixed-Signal Applications
Single supply mixed-signal applications requiring 10 or more bits of
resolution demand both a minimum of distortion and a maximum
range of voltage swing to optimize performance. To ensure the A/D
or D/A converters achieve their best performance an amplifier often
must be used for buffering or signal conditioning. The 750 µV
maximum offset voltage of the AD8601 allows the amplifier to be
used in 12-bit applications powered from a 3 V single supply, and
its rail-to-rail input and output ensure no signal clipping.
Figure 6 shows the AD8601 used as a input buffer amplifier to
the AD7476, a 12-bit 1 MHz A/D converter. As with most A/D
converters, total harmonic distortion (THD) increases with higher
source impedances. By using the AD8601 in a buffer configuration, the low output impedance of the amplifier minimizes THD
while the high input impedance and low bias current of the op
amp minimizes errors due to source impedance. The 8 MHz
gain-bandwidth product of the AD8601 ensures no signal attenuation up to 500 kHz, which is the maximum Nyquist frequency
for the AD7476.
3V
1␮F
TANT
680nF
4
1
2
+5V
2
AD8601
LEFTOUT 35
Figure 6. A Complete 3 V 12-Bit 1 MHz A/D
Conversion System
Figure 7 demonstrates how the AD8601 can be used as an output
buffer for the DAC for driving heavy resistive loads. The AD5320
is a 12-bit D/A converter that can be used with clock frequencies
up to 30 MHz and signal frequencies up to 930 kHz. The rail-torail output of the AD8601 allows it to swing within 100 mV of the
positive supply rail while sourcing 1 mA of current. The total
current drawn from the circuit is less than 1 mA, or 3 mW from
a 3 V single supply.
RIGHTOUT 36
VSS
6
5
1
AD5320
1
VOUT
0V TO 3.0V
AD8601
RL
2
Figure 7. Using the AD8601 as a DAC Output Buffer to
Drive Heavy Loads
The AD8601, AD7476, and AD5320 are all available in spacesaving SOT-23 packages.
REV. 0
U1-B
7
C2
100␮F
6
R5
20⍀
R3
2k⍀
U1 = AD8602D
The SPICE macro-model for the AD860x amplifier is available
and can be downloaded from the Analog Devices website at
http://www.analog.com. The model will accurately simulate a
number of both dc and ac parameters, including open-loop gain,
bandwidth, phase margin, input voltage range, output voltage
swing versus output current, slew rate, input voltage noise, CMRR,
PSRR, and supply current versus supply voltage. The model is
optimized for performance at 27°C. Although it will function at
different temperatures, it may lose accuracy with respect to the
actual behavior of the AD860x.
3
2
5
NOTE: ADDITIONAL PINS
OMITTED FOR CLARITY
1␮F
5
R2
2k⍀
AD1881
(AC97)
3V
3-WIRE
SERIAL
INTERFACE
4
R4
20⍀
SPICE Model
SERIAL
INTERFACE
4
3
C1
100␮F
Figure 8. A PC100 Compliant Line Output Amplifier
AD7476/AD7477
4
1
U1-A
CS
GND
8
VDD 28
␮C/␮P
SDATA
+5V
VDD
SCLK
VIN
VIN
Figure 8 shows how an AD8602 can be interfaced with an AC’97
codec to drive the line output. Here, the AD8602 is used as a
unity-gain buffer from the left and right outputs of the AC’97
CODEC. The 100 µF output coupling capacitors block dc current
and the 20 Ω series resistors protect the amplifier from short-circuits
at the jack.
5V
SUPPLY
0.1␮F
REF193
0.1␮F 10␮F
VDD
5
RS 3
Because of its low distortion and rail-to-rail input and output, the
AD860x is an excellent choice for low cost, single supply audio
applications, ranging from microphone amplification to line output
buffering. TPC 34 shows the total harmonic distortion plus noise
(THD + N) figures for the AD860x. In unity gain, the amplifier
has a typical THD + N of 0.004%, or –86 dB, even with a load
resistance of 600 Ω. This is compliant with the PC100 specification
requirements for audio in both portable and desktop computers.
–15–
AD8601/AD8602
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
0.122 (3.10)
0.114 (2.90)
0.1220 (3.100)
0.1063 (2.700)
0.0709 (1.800)
0.0590 (1.500)
5
4
1
2
3
C3684–2.5–4/00 01525
8-Lead ␮SOIC
(RM Suffix)
5-Lead SOT-23
(RT Suffix)
8
0.1181 (3.000)
0.0984 (2.500)
5
0.199 (5.05)
0.187 (4.75)
0.122 (3.10)
0.114 (2.90)
1
4
PIN 1
PIN 1
0.0256 (0.65) BSC
0.0374 (0.950) REF
0.0748 (1.900)
REF
0.0059 (0.150)
0.0000 (0.000)
0.0571 (1.450)
0.0354 (0.900)
0.0197 (0.500)
0.0118 (0.300)
SEATING
PLANE
10ⴗ
0ⴗ
0.006 (0.15)
0.002 (0.05)
0.018 (0.46)
SEATING 0.008 (0.20)
PLANE
0.0236 (0.600)
0.0039 (0.100)
0.120 (3.05)
0.112 (2.84)
0.043 (1.09)
0.037 (0.94)
0.011 (0.28)
0.003 (0.08)
33ⴗ
27ⴗ
0.028 (0.71)
0.016 (0.41)
8-Lead SOIC
(SO Suffix)
0.1968 (5.00)
0.1890 (4.80)
8
0.1574 (4.00)
0.1497 (3.80) 1
PIN 1
0.0098 (0.25)
0.0040 (0.10)
5
4
0.2440 (6.20)
0.2284 (5.80)
0.0688 (1.75)
0.0532 (1.35)
0.0500 0.0192 (0.49)
SEATING (1.27)
PLANE BSC 0.0138 (0.35)
0.0196 (0.50)
x 45ⴗ
0.0099 (0.25)
0.0098 (0.25)
0.0075 (0.19)
8ⴗ
0ⴗ 0.0500 (1.27)
0.0160 (0.41)
PRINTED IN U.S.A.
0.0512 (1.300)
0.0354 (0.900)
0.120 (3.05)
0.112 (2.84)
0.0079 (0.200)
0.0035 (0.090)
–16–
REV. 0