Page 1
Precision CMOS Single Supply
ⴚIN A
ⴙIN A
Vⴚ
OUT B
ⴚIN B
+IN B
V+
1
45
8
AD8602
OUT A
Rail-to-Rail Input/Output Wideband
a
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.
Operational Amplifiers
AD8601/AD8602
FUNCTIONAL BLOCK DIAGRAMS
5-Lead SOT-23
(RT Suffix)
OUT A
1
2
Vⴚ
AD8601
+IN
3
8-Lead SOIC
(RM Suffix)
8-Lead SOIC
(R Suffix)
OUT A
1
ⴚIN A
2
Vⴚ
AD8602
3
4
+IN A
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 avail-
able 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.
V+
5
ⴚIN
4
V+
8
OUT B
7
6
ⴚIN B
+IN B
5
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
Page 2
AD8601/AD8602–SPECIFICATIONS
ELECTRICAL CHARACTERISTICS
(VS = 3 V, VCM = VS/2, TA = 25ⴗC unless otherwise noted)
A Grade D Grade
Parameter Symbol Conditions Min Typ Max Min Typ Max Unit
INPUT CHARACTERISTICS
Offset Voltage V
Input Bias Current I
Input Offset Current I
OS
B
OS
0 V ≤ VCM ≤ 1.3 V 80 500 6,000 µV
–40°C ≤ T
–40°C ≤ T
0 V ≤ V
–40°C ≤ T
–40°C ≤ T
≤ +85°C 700 7,000 µV
A
≤ +125°C 1,100 7,000 µV
A
1
≤ 3 V
CM
≤ +85°C 1,800 7,000 µV
A
≤ +125°C 2,100 7,000 µV
A
350 750 6,000 µV
0.2 60 0.2 200 pA
–40°C ≤ T
–40°C ≤ T
≤ +85°C 100 200 pA
A
≤ +125°C 1,000 1,000 pA
A
0.1 30 0.1 100 pA
–40°C ≤ T
–40°C ≤ T
≤ +85°C 50 100 pA
A
≤ +125°C 500 500 pA
A
Input Voltage Range 0 3 0 3 V
Common-Mode Rejection Ratio CMRR V
Large Signal Voltage Gain A
VO
= 0 V to 3 V 68 83 52 65 dB
CM
VO = 0.5 V to 2.5 V
= 2 kΩ , V
R
L
= 0 V 30 100 20 60 V/mV
CM
Offset Voltage Drift ∆VOS/∆T22µV/°C
OUTPUT CHARACTERISTICS
Output Voltage High V
Output Voltage Low V
Output Current I
Closed-Loop Output Impedance Z
OH
OL
OUT
OUT
IL = 1.0 mA 2.92 2.96 2.92 2.96 V
–40°C ≤ T
≤ +125°C 2.88 2.88 V
A
IL = 1.0 mA 20 35 20 35 mV
–40°C ≤ T
≤ +125°C50 50mV
A
±30 ±30 mA
f = 1 MHz, AV = 1 12 12 Ω
POWER SUPPLY
Power Supply Rejection Ratio PSRR VS = 2.7 V to 5.5 V 67 80 56 72 dB
Supply Current/Amplifier I
SY
VO = 0 V 680 1,000 680 1,000 µA
–40°C ≤ TA ≤ +125°C 1,300 1,300 µA
DYNAMIC PERFORMANCE
Slew Rate SR RL = 2 kΩ 5.2 5.2 V/µs
Settling Time t
S
To 0.01% <0.5 <0.5 µs
Gain Bandwidth Product GBP 8.2 8.2 MHz
Phase Margin Φo 50 50 Degrees
NOISE PERFORMANCE
Voltage Noise Density e
Current Noise Density i
NOTES
1
For VCM between 1.3 V and 1.8 V, VOS may exceed specified value.
Specifications subject to change without notice.
n
e
n
n
f = 1 kHz 33 33 nV/√Hz
f = 10 kHz 18 18 nV/√Hz
0.05 0.05 pA/√Hz
–2–
REV. 0
Page 3
AD8601/AD8602
ELECTRICAL CHARACTERISTICS
(VS = 5.0 V, VCM = VS/2, TA = 25ⴗC unless otherwise noted)
A Grade D Grade
Parameter Symbol Conditions Min Typ Max Min Typ Max Unit
INPUT CHARACTERISTICS
Offset Voltage V
Input Bias Current I
Input Offset Current I
OS
B
OS
0 V ≤ VCM ≤ 5 V 80 500 6,000 µV
–40°C ≤ T
≤ +125°C 1,300 7,000 µV
A
0.2 60 0.2 200 pA
–40°C ≤ T
–40°C ≤ T
≤ +85°C 100 200 pA
A
≤ +125°C 1,000 1,000 pA
A
0.1 30 0.1 100 pA
–40°C ≤ T
–40°C ≤ T
≤ +85°C 50 100 pA
A
≤ +125°C 500 500 pA
A
Input Voltage Range 0 5 0 5 V
Common-Mode Rejection Ratio CMRR VCM = 0 V to 5 V 74 89 56 67 dB
Large Signal Voltage Gain A
VO
VO = 0.5 V to 4.5 V 30 100 20 60 V/mV
R
= 2 kΩ, VCM = 0 V
L
Offset Voltage Drift ∆VOS/∆T22µV/°C
OUTPUT CHARACTERISTICS
Output Voltage High V
Output Voltage Low V
Output Current I
Closed-Loop Output Impedance Z
OH
OL
OUT
OUT
IL = 1.0 mA 4.925 4.975 4.925 4.975 V
I
= 10 mA 4.7 4.77 4.7 4.77 V
L
–40°C ≤ T
≤ +125°C 4.6 4.6 V
A
IL = 1.0 mA 15 30 15 30 mV
I
= 10 mA 125 175 125 175 mV
L
–40°C ≤ T
≤ +125°C 250 250 mV
A
±50 ±50 mA
f = 1 MHz, AV = 1 10 10 Ω
POWER SUPPLY
Power Supply Rejection Ratio PSRR VS = 2.7 V to 5.5 V 67 80 56 72 dB
Supply Current/Amplifier I
SY
VO = 0 V 750 1,200 750 1,200 µA
–40°C ≤ TA ≤ +125°C 1,500 1,500 µA
DYNAMIC PERFORMANCE
Slew Rate SR RL = 2 kΩ 66V/µs
Settling Time t
S
To 0.01% < 1.0 < 1.0 µs
Full Power Bandwidth BWp < 1% Distortion 360 360 kHz
Gain Bandwidth Product GBP 8.4 8.4 MHz
Phase Margin Φo 55 55 Degrees
NOISE PERFORMANCE
Voltage Noise Density e
e
Current Noise Density i
Specifications subject to change without notice.
n
n
n
f = 1 kHz 33 33 nV/√Hz
f = 10 kHz 18 18 nV/√Hz
f = 1 kHz 0.05 0.05 pA/√Hz
–3–REV. 0
Page 4
AD8601/AD8602
WARNING!
ESD SENSITIVE DEVICE
ABSOLUTE MAXIMUM RATINGS*
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 V
Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GND to V
S
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
*Stresses above those listed under Absolute Maximum Ratings may cause perma-
nent 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
Temperature Package Package Branding
Model Range Description Option Information
AD8601ART –40°C to +125°C 5-Lead SOT-23 RT-5 AAA
AD8601DRT –40°C to +125°C 5-Lead SOT-23 RT-5 AAD
AD8602AR –40°C to +125°C 8-Lead SOIC SO-8
AD8602DR –40°C to +125°C 8-Lead SOIC SO-8
AD8602ARM –40°C to +125°C 8-Lead MSOP RM-8 ABA
AD8602DRM –40°C to +125°C 8-Lead MSOP RM-8 ABD
Package Type JA*
JC
Unit
5-Lead SOT-23 (RT) 230 92 °C/W
8-Lead SOIC (R) 158 43 °C/W
8-Lead MSOP (RM) 210 45 °C/W
*θJA is specified for worst-case conditions, i.e., θ
socket for PDIP packages; θ
board for surface mount packages.
is specified for device soldered onto a circuit
JA
is specified for device in
JA
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–
REV. 0
Page 5
3,000
TCVOS – V/ⴗC
60
30
0
0101
QUANTITY – Amplifiers
23456789
50
40
20
10
VS = 5V
T
A
= 25ⴗC TO 85ⴗC
VS = 3V
= 25ⴗC
T
A
2,500
V
= 0V TO 3V
CM
2,000
1,500
1,000
QUANTITY – Amplifiers
500
Typical Performance Characteristics–
AD8601/AD8602
0
ⴚ1.0
ⴚ0.6 ⴚ0.4 ⴚ0.2
ⴚ0.8
INPUT OFFSET VOLTAGE – mV
TPC 1. Input Offset Voltage Distribution
3,000
VS = 5V
= 25ⴗC
T
A
2,500
V
= 0V TO 5V
CM
2,000
1,500
1,000
QUANTITY – Amplifiers
500
0
ⴚ1.0
ⴚ0.6 ⴚ0.4 ⴚ0.2
ⴚ0.8
INPUT OFFSET VOLTAGE – mV
TPC 2. Input Offset Voltage Distribution
60
50
40
30
20
QUANTITY – Amplifiers
10
0
0101
VS = 3V
TA = 25ⴗC TO 85ⴗC
23456789
TPC 3. Input Offset Voltage Drift Distribution
0
0
TCVOS – V/ⴗC
0.2 0.4 0.6 0.8
0.2 0.4 0.6 0.8
1.0
1.0
TPC 4. Input Offset Voltage Drift Distribution
1.5
VS = 3V
= 25ⴗC
T
0
03.00.5
A
1.0 1.5 2.0 2.5
COMMON-MODE VOLTAGE – V
1.0
0.5
ⴚ0.5
ⴚ1.0
INPUT OFFSET VOLTAGE – mV
ⴚ1.5
ⴚ2.0
TPC 5. Input Offset Voltage vs. Common-Mode Voltage
1.5
VS = 5V
= 25ⴗC
T
A
1.0
0.5
0
ⴚ0.5
ⴚ1.0
INPUT OFFSET VOLTAGE – mV
ⴚ1.5
ⴚ2.0
01
2345
COMMON-MODE VOLTAGE – V
TPC 6. Input Offset Voltage vs. Common-Mode Voltage
–5–REV. 0
Page 6
AD8601/AD8602
300
VS = 3V
250
200
150
100
INPUT BIAS CURRENT – pA
50
0
ⴚ40
ⴚ25 ⴚ10
5 35 50 80 95 110
TEMPERATURE – ⴗC
TPC 7. Input Bias Current vs. Temperature
300
VS = 5V
250
200
150
30
VS = 3V
25
20
15
10
INPUT OFFSET CURRENT – pA
5
12520 65
0
ⴚ40
ⴚ25 ⴚ10
5 35 50 80 95 110
TEMPERATURE – ⴗC
12520 65
TPC 10. Input Offset Current vs. Temperature
30
VS = 5V
25
20
15
100
INPUT BIAS CURRENT – pA
50
0
ⴚ40
ⴚ25 ⴚ10
5 35 50 80 95 110
TEMPERATURE – ⴗC
12520 65
TPC 8. Input Bias Current vs. Temperature
5
VS = 5V
= 25ⴗC
T
A
4
3
2
INPUT BIAS CURRENT – pA
1
0
0 0.5 1.0 1.5 4.5 5.0
2.0 2.5 3.0 3.5
COMMON-MODE VOLTAGE – V
4.0
TPC 9. Input Bias Current vs. Common-Mode Voltage
10
INPUT OFFSET CURRENT – pA
5
0
ⴚ40
ⴚ25 ⴚ10
5 35 50 80 95 110
TEMPERATURE – ⴗC
12520 65
TPC 11. Input Offset Current vs. Temperature
10k
VS = 2.7V
= 25ⴗC
T
A
1k
100
10
OUTPUT VOLTAGE – mV
1
0.1
0.001 1000.01
SOURCE
0.1 1 10
LOAD CURRENT – mA
SINK
TPC 12. Output Voltage to Supply Rail vs. Load Current
–6–
REV. 0
Page 7
AD8601/AD8602
10k
VS = 5V
= 25ⴗC
T
A
1k
100
10
OUTPUT VOLTAGE – mV
1
0.1
0.001 1000.01
0.1 1 10
LOAD CURRENT – mA
SOURCE
SINK
TPC 13. Output Voltage to Supply Rail vs. Load Current
5.1
VS = 5V
5.0
VOH @ 1mA LOAD
4.9
4.8
@ 10mA LOAD
V
OH
4.7
OUTPUT VOLTAGE – V
4.6
35
VS = 2.7V
30
25
VOL @ 1mA LOAD
TEMPERATURE – ⴗC
OUTPUT VOLTAGE – mV
20
15
10
5
0
ⴚ40
ⴚ25 ⴚ10
5 35 50 80 95 110
TPC 16. Output Voltage Swing vs. Temperature
2.67
VS = 2.7V
2.66
2.65
VOH @ 1mA LOAD
2.64
OUTPUT VOLTAGE – V
2.63
12520 65
4.5
ⴚ40
ⴚ25 ⴚ10
5 35 50 80 95 110
TEMPERATURE – ⴗC
12520 65
TPC 14. Output Voltage Swing vs. Temperature
250
VS = 5V
200
150
VOL @ 10mA LOAD
100
OUTPUT VOLTAGE – mV
50
VOL @ 1mA LOAD
0
ⴚ40
ⴚ25 ⴚ10
5 35 50 80 95 110
TEMPERATURE – ⴗC
12520 65
TPC 15. Output Voltage Swing vs. Temperature
2.62
ⴚ40
ⴚ25 ⴚ10
5 35 50 80 95 110
TEMPERATURE – ⴗC
12520 65
TPC 17. Output Voltage Swing vs. Temperature
VS = 3V
= NO LOAD
R
L
= 25ⴗC
T
A
80
60
40
20
GAIN – dB
0
1k 100M10k
100k 1M 10M
FREQUENCY – Hz
45
90
135
180
TPC 18. Open-Loop Gain and Phase vs. Frequency
PHASE SHIFT – Degrees
–7–REV. 0
Page 8
AD8601/AD8602
VS = 5V
= NO LOAD
R
L
= 25ⴗC
T
A
80
60
40
20
GAIN – dB
0
1k 100M10k
100k 1M 10M
FREQUENCY – Hz
45
90
135
180
TPC 19. Open-Loop Gain and Phase vs. Frequency
VS = 3V
= 25ⴗC
T
A
40
20
0
CLOSED-LOOP GAIN – dB
AV = 100
AV = 10
AV = 1
PHASE SHIFT – Degrees
3.0
2.5
VS = 2.7V
= 2.6V p-p
V
IN
= 2k⍀
R
2.0
L
= 25ⴗC
T
A
= 1
A
V
1.5
1.0
OUTPUT SWING – V p-p
0.5
0
1k 10M10k
100k 1M
FREQUENCY – Hz
TPC 22. Closed-Loop Output Voltage Swing vs. Frequency
6
5
VS = 5V
= 4.9V p-p
V
IN
4
= 2k⍀
R
L
= 25ⴗC
T
A
= 1
A
V
3
2
OUTPUT SWING – V p-p
1
1k 100M10k
100k 1M 10M
FREQUENCY – Hz
TPC 20. Closed-Loop Gain vs. Frequency
VS = 5V
= 25ⴗC
T
A
40
20
0
CLOSED-LOOP GAIN – dB
1k 100M10k
AV = 100
AV = 10
AV = 1
100k 1M 10M
FREQUENCY – Hz
TPC 21. Closed-Loop Gain vs. Frequency
0
1k 10M10k
100k 1M
FREQUENCY – Hz
TPC 23. Closed-Loop Output Voltage Swing vs. Frequency
200
VS = 3V
180
= 25ⴗC
T
A
160
140
120
100
80
60
OUTPUT IMPEDANCE – ⍀
40
20
0
100 10M1k
FREQUENCY – Hz
AV = 100
AV = 10
AV = 1
10k 100k 1M
TPC 24. Output Impedance vs. Frequency
–8–
REV. 0
Page 9
AD8601/AD8602
p
p
200
VS = 5V
180
= 25ⴗC
T
A
160
140
120
100
80
60
OUTPUT IMPEDANCE – ⍀
40
20
0
100 10M1k
AV = 100
AV = 10
AV = 1
10k 100k 1M
FREQUENCY – Hz
TPC 25. Output Impedance vs. Frequency
160
VS = 3V
140
= 25ⴗC
T
A
120
100
80
60
40
20
0
COMMON-MODE REJECTION – dB
ⴚ20
ⴚ40
1k 20M10k
100k 1M
FREQUENCY – Hz
10M
TPC 26. Common-Mode Rejection Ratio vs. Frequency
160
VS = 5V
140
= 25ⴗC
T
A
120
100
80
60
40
20
0
POWER SUPPLY REJECTION – dB
ⴚ20
ⴚ40
100 10M1k
10k 100k 1M
FREQUENCY – Hz
TPC 28. Power Supply Rejection Ratio vs. Frequency
70
VS = 2.7V
=
R
L
60
T
= 25ⴗC
A
50
ⴚOS
40
30
20
SMALL SIGNAL OVERSHOOT – %
10
0
10 1k100
CAPACITANCE –
+OS
F
TPC 29. Small Signal Overshoot vs. Load Capacitance
160
VS = 5V
140
TA = 25ⴗC
120
100
80
60
40
20
0
COMMON-MODE REJECTION – dB
ⴚ20
ⴚ40
1k 20M10k
100k 1M
FREQUENCY – Hz
10M
TPC 27. Common-Mode Rejection Ratio vs. Frequency
70
VS = 5V
=
R
L
60
= 25ⴗC
T
A
50
40
30
20
SMALL SIGNAL OVERSHOOT – %
10
0
10 1k100
ⴚOS
+OS
CAPACITANCE –
F
TPC 30. Small Signal Overshoot vs. Load Capacitance
–9–REV. 0
Page 10
AD8601/AD8602
1.2
VS = 5V
1.0
0.8
0.6
0.4
0.2
SUPPLY CURRENT PER AMPLIFIER – mA
0
ⴚ40
ⴚ25 ⴚ10
5 35 50 80 95 110
TEMPERATURE – ⴗC
12520 65
TPC 31. Supply Current per Amplifier vs. Temperature
1.0
VS = 3V
0.8
0.6
0.4
0.1
VS = 5V
= 25ⴗC
T
A
G = 10
0.01
THD + N – %
0.001
0.0001
20 20k
100 1k 10k
RL = 600⍀
G = 1
FREQUENCY – Hz
RL = 600⍀
RL = 2k⍀
RL = 10k⍀
RL = 2k⍀
RL = 10k⍀
TPC 34. Total Harmonic Distortion + Noise vs. Frequency
64
VS = 2.7V
56
48
40
32
24
T
= 25ⴗC
A
0.2
SUPPLY CURRENT PER AMPLIFIER – mA
0
ⴚ40
ⴚ25 ⴚ10
5 35 50 80 95 110
TEMPERATURE – ⴗC
12520 65
TPC 32. Supply Current per Amplifier vs. Temperature
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
SUPPLY CURRENT PER AMPLIFIER – mA
0
0
SUPPLY VOLTAGE – V
612345
TPC 33. Supply Current per Amplifier vs. Supply Voltage
16
VOLTAGE NOISE DENSITY – nV/ Hz
8
0
0 5 10 15 20 25
FREQUENCY – kHz
TPC 35. Voltage Noise Density vs. Frequency
208
VS = 2.7V
182
156
130
104
78
52
VOLTAGE NOISE DENSITY – nV/ Hz
26
= 25ⴗC
T
A
0
0 0.5 1.0 1.
FREQUENCY – kHz
5
2.0 2.5
TPC 36. Voltage Noise Density vs. Frequency
–10–
REV. 0
Page 11
AD8601/AD8602
208
VS = 5V
182
156
130
104
78
52
VOLTAGE NOISE DENSITY – nV/ Hz
26
= 25ⴗC
T
A
0
0 0.5 1.0 1.5 2.0 2.5
FREQUENCY – kHz
TPC 37. Voltage Noise Density vs. Frequency
64
VS = 5V
56
48
40
32
T
A
= 25ⴗC
VS = 5V
TA = 25ⴗC
VOLTAGE – 2.5V/DIV
TIME – 1s/DIV
TPC 40. 0.1 Hz to 10 Hz Input Voltage Noise
VS = 5V
RL = 10k⍀
= 100pF
C
L
= 25ⴗC
T
A
24
16
VOLTAGE NOISE DENSITY – nV/ Hz
8
0
0 5 10 15 20 25
FREQUENCY – kHz
TPC 38. Voltage Noise Density vs. Frequency
VS = 2.7V
TA = 25ⴗC
VOLTAGE – 2.5V/DIV
TIME – 1s/DIV
TPC 39. 0.1 Hz to 10 Hz Input Voltage Noise
VOLTAGE – 50mV/DIV
TIME – 200ns/DIV
TPC 41. Small Signal Transient Response
VS = 5V
TA = 25ⴗC
VOLTAGE – 2.5V/DIV
TIME – 1s/DIV
TPC 42. Small Signal Transient Response
–11–REV. 0
Page 12
AD8601/AD8602
VS = 5V
RL = 10k⍀
= 200pF
C
L
= 1
A
V
= 25ⴗC
T
A
VOLTAGE – 1.0V/DIV
TIME – 400ns/DIV
TPC 43. Large Signal Transient Response
VS = 2.7V
RL = 10k⍀
= 200pF
C
L
= 1
A
V
= 25ⴗC
T
A
VOLTAGE – 500mV/DIV
+0.1%
ERROR
ⴚ0.1%
VOLTAGE – V
ERROR
VOLTAGE – 1V/DIV
VS = 5V
= 10k⍀
R
L
= 1
A
V
= 25ⴗC
T
A
V
IN
V
OUT
TIME – 2.0s/DIV
TPC 46. No Phase Reversal
V
V
OUT
IN
VS = 5V
RL = 10k⍀
= 2V p-p
V
O
T
= 25ⴗC
A
TIME – 400ns/DIV
TPC 44. Large Signal Transient Response
VS = 2.7V
= 10k⍀
R
L
= 1
A
V
= 25ⴗC
T
A
TIME – 2.0s/DIV
VOLTAGE – 1V/DIV
V
IN
V
OUT
TPC 45. No Phase Reversal
VIN TRACE – 0.5V/DIV
TRACE – 10mV/DIV
V
OUT
TIME – 100ns/DIV
TPC 47. Settling Time
2.0
VS = 2.7V
1.5
= 25ⴗC
T
A
1.0
0.5
0
ⴚ0.5
OUTPUT SWING – V
ⴚ1.0
ⴚ1.5
ⴚ2.0
300 600350 400 450 500 550
0.1% 0.01%
0.01%0.1%
SETTLING TIME – ns
TPC 48. Output Swing vs. Settling Time
–12–
REV. 0
Page 13
AD8601/AD8602
VCM – V
0.7
0.4
ⴚ1.4
0
51
V
OS
– mV
234
ⴚ0.2
ⴚ0.5
ⴚ0.8
ⴚ1.1
0.1
5
VS = 5V
4
= 25ⴗC
T
A
3
2
1
0
ⴚ1
OUTPUT SWING – V
ⴚ2
ⴚ3
ⴚ4
ⴚ5
0 1,000200 400 600 800
0.1% 0.01%
0.01%0.1%
SETTLING TIME – ns
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 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 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.
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.
Rail-to-Rail Input Stage
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
DigiTrim is a trademark of Analog Devices.
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.
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.
Figure 1. Burr Brown OPA2340UR Input Offset Voltage
vs. Common-Mode Voltage, 24 SOIC Units @ 25
0.7
0.4
0.1
ⴚ0.2
– mV
OS
ⴚ0.5
V
ⴚ0.8
ⴚ1.1
ⴚ1.4
0
234
VCM – V
°
C
Figure 2. AD8602AR Input Offset Voltage vs.
°
Common-Mode Voltage, 300 SOIC Units @ 25
C
–13–REV. 0
51
Page 14
AD8601/AD8602
Input Overvoltage Protection
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.
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.
Power-On Time
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.
Using the AD8602 in High Source Impedance Applications
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.
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:
BW
=
1
(1)
247π . MΩ
()
C
F
Using a 10 pF feedback capacitor limits the bandwidth to approximately 3.3 kHz.
10pF
(OPTIONAL)
4.7m⍀
V
D1
AD8601
OUT
4.7V/A
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
Q1
2N3905
R1
100⍀
2.49k⍀
R
SENSE
0.1⍀
3V
1/2 AD8602
RETURN TO
GROUND
MONITOR
OUTPUT
Figure 4. A Low-Side Current Monitor
R
MONITOR
OUTPUT
3V
100⍀
2N3904
SENSE
0.1⍀
R1
Q1
R2
2.49k⍀
I
3V
1/2
AD8602
L
V+
0.1F
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:
Monitor Output R
=×
R
SENSE
1
R
×2
I
L
(2)
For the high-side monitor, the monitor output voltage is:
–14–
REV. 0
Page 15
AD8601/AD8602
U1-A
R2
2k⍀
4
C1
100F
+5V
1
8
2
3
+5V
V
DD
V
DD
LEFT
OUT
AD1881
(AC97)
RIGHT
OUT
V
SS
R4
20⍀
5
6
7
R5
20⍀
C2
100F
NOTE: ADDITIONAL PINS
OMITTED FOR CLARITY
U1-B
U1 = AD8602D
R3
2k⍀
28
35
36
Monitor Output V R
=+−
()
R
×
SENSE
1
R
×2
I
L
(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.
680nF
1F
TANT
3V
REF193
0.1F
0.1F10F
5V
SUPPLY
PC100 Compliance for Computer Audio Applications
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.
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.
V
IN
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.
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.
4
R
S
3
3-WIRE
SERIAL
INTERFACE
5
1
AD8601
2
V
DD
V
IN
GND
AD7476/AD7477
SCLK
SDATA
CS
SERIAL
INTERFACE
C/P
Figure 8. A PC100 Compliant Line Output Amplifier
SPICE Model
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.
3V
1F
4
3
2
4
5
AD5320
6
2
1
5
1
AD8601
V
OUT
0V TO 3.0V
R
L
–15–REV. 0
Page 16
AD8601/AD8602
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
0.0709 (1.800)
0.0590 (1.500)
0.0512 (1.300)
0.0354 (0.900)
0.0059 (0.150)
0.0000 (0.000)
0.1220 (3.100)
0.1063 (2.700)
54
1 3 2
PIN 1
0.0748 (1.900)
REF
5-Lead SOT-23
(RT Suffix)
0.1181 (3.000)
0.0984 (2.500)
0.0374 (0.950) REF
0.0571 (1.450)
0.0354 (0.900)
0.0197 (0.500)
0.0118 (0.300)
SEATING
PLANE
0.1574 (4.00)
0.1497 (3.80)
0.0079 (0.200)
0.0035 (0.090)
10ⴗ
0.0236 (0.600)
0ⴗ
0.0039 (0.100)
0.1968 (5.00)
0.1890 (4.80)
85
8-Lead SOIC
(SO Suffix)
0.2440 (6.20)
41
0.2284 (5.80)
0.122 (3.10)
0.114 (2.90)
0.006 (0.15)
0.002 (0.05)
SEATING
PLANE
0.122 (3.10)
0.114 (2.90)
85
PIN 1
0.0256 (0.65) BSC
0.120 (3.05)
0.112 (2.84)
0.018 (0.46)
0.008 (0.20)
8-Lead SOIC
(RM Suffix)
0.199 (5.05)
0.187 (4.75)
41
0.043 (1.09)
0.037 (0.94)
0.011 (0.28)
0.003 (0.08)
0.120 (3.05)
0.112 (2.84)
33ⴗ
27ⴗ
C3684–2.5–4/00 01525
0.028 (0.71)
0.016 (0.41)
PIN 1
0.0098 (0.25)
0.0040 (0.10)
SEATING
PLANE
0.0500
(1.27)
BSC
0.0688 (1.75)
0.0532 (1.35)
0.0192 (0.49)
0.0138 (0.35)
0.0098 (0.25)
0.0075 (0.19)
0.0196 (0.50)
0.0099 (0.25)
8ⴗ
0ⴗ
0.0500 (1.27)
0.0160 (0.41)
x 45ⴗ
PRINTED IN U.S.A.
–16–
REV. 0
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