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Precision Micropower Low Noise CMOS Rail-
to-Rail Input/Output Operational Amplifiers
AD8603/AD8607/AD8609
FEATURES
Low offset voltage: 50 V max
Low input bias current: 1 pA max
Single-supply operation: 1.8 V to 5 V
Low noise: 22 nV/Hz
Micropower: 50 A max
Low distortion
No phase reversal
Unity gain stable
APPLICATIONS
Battery-powered instrumentation
Multipole filters
Sensors
Low power ASIC input or output amplifiers
GENERAL DESCRIPTION
The AD8603/AD8607/AD8609 are, single/dual/quad micro-
power rail-to-rail input and output amplifiers, respectively, that
features very low offset voltage as well as low input voltage and
current noise.
These amplifiers use a patented trimming technique that
achieves superior precision without laser trimming. The parts
are fully specified to operate from 1.8 V to 5.0 V single supply
or from 0.9 V to 2.5 V dual supply. The combination of low
offsets, low noise, very low input bias currents, and low power
consumption make the AD8603/AD8607/AD8609 especially
useful in portable and loop-powered instrumentation.
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 low power single-supply
systems.
The AD8603 is available in a tiny 5-lead TSOT-23 package. The
AD8607 is available in 8-lead MSOP and SOIC packages. The
AD8609 is available in 14-lead TSSOP and SOIC packages.
PIN CONFIGURATIONS
AD8603
TOP VIEW
(Not to Scale)
OUT
1
V
2
+IN
3
V+
IN
5
4
04356-0-001
Figure 1. 5-Lead TSOT-23 (UJ Suffix)
IN A
+IN A
V
OUT B
IN B
+IN B
V+
1
4
5
8
AD8607
OUT A
04356-0-045
Figure 2. 8-Lead MSOP (RM Suffix)
1
2
3
4
8
7
6
5
AD8607
IN A
V
+IN A
OUT B
IN B
V+
+IN B
OUT A
04356-0-047
Figure 3. 8-Lead SOIC (R Suffix)
OUT A
IN A
+IN A
V+
+IN B
IN B
OUT B
IN D
+IN D
V
OUT D
IN C
OUT C
+IN C
14
8
1
7
AD8609
04356-0-044
Figure 4. 14-Lead TSSOP (RU Suffix)
IN A
+IN A
V+
+IN B
IN B
OUT B
OUT D
IN D
+IN D
V
+IN C
IN C
OUT C
OUT A
AD8609
1
2
3
4
5
6
7
14
13
12
11
10
9
8
04356-0-046
Figure 5. 14-Lead SOIC (R Suffix)
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: 781.326.8703
2003 Analog Devices, Inc. All rights reserved.
Rev. A
AD8603/AD8607/AD8609
TABLE OF CONTENTS
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 5
Typical Performance Characteristics ............................................. 6
Applications..................................................................................... 12
No Phase Reversal ...................................................................... 12
Input Overvoltage Protection ................................................... 12
Driving Capacitive Loads .......................................................... 12
Proximity Sensors....................................................................... 13
Composite Amplifiers................................................................ 13
Battery-Powered Applications .................................................. 14
Photodiodes ................................................................................ 14
Outline Dimensions ....................................................................... 15
Ordering Guide .......................................................................... 16
REVISION HISTORY
10/03--Data Sheet Changed from Rev. 0 to Rev. A
Change Page
Added AD8607 and AD8609 parts ..............................Universal
Changes to Specifications ............................................................ 3
Changes to Figure 35.................................................................. 10
Added Figure 41.......................................................................... 11
Rev. A | Page 2 of 16
AD8603/AD8607/AD8609
SPECIFICATIONS
Table 1. Electrical Characteristics @ V
S
= 5 V, V
CM
= V
S
/2, T
A
= 25C, unless otherwise noted
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
INPUT CHARACTERISTICS
Offset Voltage
V
OS
V
S
= 3.3 V @ V
CM
= 0.5 V and 2.8 V
12
50
V
0.3 V < V
CM
< +5.2 V
40
300
V
40C < T
A
< +125C, 0.3 V < V
CM
< +5.2 V
700
V
Offset Voltage Drift
V
OS
/T
40C < T
A
< +125C
1
4.5
V/C
Input Bias Current
I
B
0.2
1
pA
40C < T
A
< +85C
50
pA
40C < T
A
< +125C
500
pA
Input Offset Current
I
OS
0.1
0.5
pA
40C < T
A
< +85C
50
pA
40C < T
A
< +125C
250
pA
Input Voltage Range
IVR
0.3
+5.2
V
Common-Mode Rejection Ratio
CMRR
0 V < V
CM
< 5 V
85
100
dB
40C < T
A
< +125C
80
dB
Large Signal Voltage Gain
A
VO
R
L
= 10 k, 0.5 V <V
O
< 4.5 V
AD8603
400
1000
V/mV
AD8607/AD8609
250
450
V/mV
Input Capacitance
C
DIFF
1.9
pF
C
CM
2.5
pF
OUTPUT CHARACTERISTICS
Output Voltage High
V
OH
I
L
= 1 mA
4.95
4.97
V
40C to +125C
4.9
V
I
L
= 10 mA
4.65
4.97
V
40C to +125C
4.50
V
Output Voltage Low
V
OL
I
L
= 1 mA
16
30
mV
40C to +125C
50
mV
I
L
= 10 mA
160
250
mV
40C to +125C
330
mV
Output Current
I
OUT
80
mA
Closed-Loop Output Impedance
Z
OUT
f = 10 kHz, A
V
= 1
36
POWER SUPPLY
Power Supply Rejection Ratio
PSRR
1.8 V < V
S
< 5 V
80
100
dB
Supply Current/Amplifier
I
SY
V
O
= 0 V
40
50
A
40C
<T
A
< +125C
60
A
DYNAMIC PERFORMANCE
Slew Rate
SR
R
L
= 10 k
0.1
V/s
Settling Time 0.1%
t
S
G= 1, 2 V Step
23
s
Gain Bandwidth Product
GBP
R
L
= 100 k
400
kHz
R
L
= 10 k
316
kHz
Phase Margin
O
R
L
= 10 k, R
L
= 100 k
70
Degrees
NOISE PERFORMANCE
Peak-to-Peak Noise
e
n p-p
0.1 Hz to 10 Hz
2.3
3.5
V
Voltage Noise Density
e
n
f = 1 kHz
25
nV/Hz
f = 10 kHz
22
nV/Hz
Current Noise Density
i
n
f = 1 kHz
0.05
pA/Hz
Channel Separation
Cs
f = 10 kHz
115
dB
f = 100 kHz
110
dB
Rev. A | Page 3 of 16
AD8603/AD8607/AD8609
Table 2. Electrical Characteristics @ V
S
= 1.8 V, V
CM
= V
S
/2, T
A
= 25C, unless otherwise noted
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
INPUT CHARACTERISTICS
Offset Voltage
V
OS
V
S
= 3.3 V @ V
CM
= 0.5 V and 2.8 V
12
50
V
0.3 V < V
CM
< +1.8 V
40
300
V
40C < T
A
< +85C, 0.3 V < V
CM
< +1.8 V
500
V
40C < T
A
< +125C, 0.3 V < V
CM
< +1.7 V
700
V
Offset Voltage Drift
V
OS
/T
40C < T
A
< +125C
1
4.5
V/C
Input Bias Current
I
B
0.2
1
pA
40C < T
A
< +85C
50
pA
40C < T
A
< +125C
500
pA
Input Offset Current
I
OS
0.1
0.5
pA
40C < T
A
< +85C
50
pA
40C < T
A
< +125C
250
pA
Input Voltage Range
IVR
0.3
+1.8
V
Common-Mode Rejection Ratio
CMRR
0 V < V
CM
< 1.8 V
80
98
dB
40C < T
A
< +85C
70
dB
Large Signal Voltage Gain
A
VO
R
L
= 10 k, 0.5 V <V
O
< 4.5 V
AD8603
150
3000
V/mV
AD8607/AD8609
100
2000
V/mV
Input Capacitance
C
DIFF
2.1
pF
C
CM
3.8
pF
OUTPUT CHARACTERISTICS
Output Voltage High
V
OH
I
L
= 1 mA
1.65
1.72
V
40C to +125C
1.6
V
Output Voltage Low
V
OL
I
L
= 1 mA
38
60
mV
40C to +125C
80
mV
Output Current
I
OUT
7
mA
Closed-Loop Output Impedance
Z
OUT
f = 10 kHz, A
V
= 1
36
POWER SUPPLY
Power Supply Rejection Ratio
PSRR
1.8 V < V
S
< 5 V
80
100
dB
Supply Current/Amplifier
I
SY
V
O
= 0 V
40
50
A
40C < T
A
< +85C
60
A
DYNAMIC PERFORMANCE
Slew Rate
SR
R
L
= 10 k
0.1
V/s
Settling Time 0.1%
t
S
G= 1, 1 V Step
9.2
s
Gain Bandwidth Product
GBP
R
L
= 100 k
385
kHz
R
L
= 10 k
316
kHz
Phase Margin
O
R
L
= 10 k, R
L
= 100 k
70
Degrees
NOISE PERFORMANCE
Peak-to-Peak Noise
e
n p-p
0.1 Hz to 10 Hz
2.3
3.5
V
Voltage Noise Density
e
n
f = 1 kHz
25
nV/Hz
f = 10 kHz
22
nV/Hz
Current Noise Density
i
n
f = 1 kHz
0.05
pA/Hz
Channel Separation
Cs
f = 10 kHz
115
dB
f = 100 kHz
110
dB
Rev. A | Page 4 of 16
AD8603/AD8607/AD8609
ABSOLUTE MAXIMUM RATINGS
Table 3. AD8603/AD8607/AD8609 Stress Ratings
1, 2
Parameter Rating
Supply Voltage
6 V
Input Voltage
GND to V
S
Differential Input Voltage
6 V
Output Short-Circuit Duration to GND
Indefinite
Storage Temperature Range
All Packages
65C to +150C
Lead Temperature Range (Soldering, 60 Sec)
300C
Operating Temperature Range
40C to +125C
Junction Temperature Range
All Packages
65C to +150C
Table 4. Package Characteristics
Package Type
JA
3
JC
Unit
5-Lead TSOT-23 (UJ)
207
61
C/W
8-Lead MSOP (RM)
210
45
C/W
8-Lead SOIC (R)
158
43
C/W
14-Lead SOIC (R)
120
36
C/W
14-Lead TSSOP (RU)
180
35
C/W
1
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.
2
Absolute maximum ratings apply at 25C, unless otherwise noted.
3
JA
is specified for the worst-case conditions, i.e.,
JA
is specified for device
soldered in circuit board for surface-mount packages.
ESD 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 these parts feature
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.
Rev. A | Page 5 of 16
AD8603/AD8607/AD8609
TYPICAL PERFORMANCE CHARACTERISTICS
V
OS
(
V)
NUMBE
R OF AMP
L
IFIE
RS
210
0
400
800
1200
0
150
200
600
1000
150
30
30
90
210
270
90
1600
1400
270
04356-0-002
1800
2000
2200
2400
2600
V
S
= 5V
T
A
= 25C
V
CM
= 0V to 5V
Figure 6. Input Offset Voltage Distribution
TCVOS (
V/C)
NUMBE
RS
OF AMP
L
IFIE
RS
0
0
10
20
30
1.6
3.2
5
15
25
0.4 0.8 1.2
2.0 2.4 2.8
3.6 4.0 4.4 4.8
V
S
= 2.5V
T
A
= 40C TO +125C
V
CM
= 0V
04356-0-003
Figure 7. Input Offset Voltage Drift Distribution
V
CM
(V)
V
OS
(
V)
0.0
300
100
100
300
1.5
3.5
5.0
1.0
0.5
2.5
4.5
4.0
3.0
2.0
200
150
250
50
0
50
150
200
250
04356-0-004
V
S
= 5V
T
A
= 25C
Figure 8. Input Offset Voltage vs. Common-Mode Voltage
V
CM
(V)
V
OS
(
V)
0.0
300
100
100
300
0.9
2.1
3.0
0.6
0.3
1.5
2.7
2.4
1.8
1.2
200
150
250
50
0
50
150
200
250
3.3
V
S
= 3.3V
T
A
= 25C
04356-0-005
V
CM
(V)
Figure 9. Input Offset Voltage vs. Common-Mode Voltage
TEMPERATURE (C)
INP
U
T BIAS
CURRE
NT (pA)
0
0
150
300
400
50
100
125
25
75
100
50
350
250
200
04356-0-006
V
S
= 2.5V
Figure 10. Input Bias vs. Temperature
LOAD CURRENT (mA)
OU
TPU
T
VOLTA
GE TO SU
PPLY R
A
I
L (
m
V)
0.001
0.01
0.1
10
100
0.01
0.1
1
10
1000
1
SINK
SOURCE
V
S
= 5V
T
A
= 25C
04356-0-007
Figure 11. Output Voltage to Supply Rail vs. Load Current
Rev. A | Page 6 of 16
AD8603/AD8607/AD8609
TEMPERATURE (C)
OUTPUT SW
ING (
m
V)
40
0
50
100
350
25 10
125
20
35
50
65
80
95
110
5
150
250
300
200
04356-0-008
V
OL
@ 1mA LOAD
V
DD
V
OH
@ 1mA LOAD
V
DD
V
OH
@ 10mA LOAD
V
OL
@ 10mA LOAD
V
S
= 5V
T
A
= 25C
Figure 12. Output Voltage Swing vs. Temperature
V
S
= 2.5V
R
L
= 100k
C
L
= 20pF
= 70.9
04356-0-010
1k
10k
100k
1M
10M
FREQUENCY (Hz)
PH
A
SE (
D
egree)
OPEN-
L
OOP GAIN (
d
B)
20
80
20
80
100
60
40
0
40
60
100
45
180
45
180
225
135
90
0
90
135
225
Figure 13. Open-Loop Gain and Phase vs. Frequency
FREQUENCY (kHz)
OUTPUT SW
ING (
V
p-
p)
0.01
0.0
0.5
4.0
5.0
0.1
1
100
4.5
3.5
3.0
2.0
2.5
1.5
1.0
10
04356-0-011
V
S
= 5V
V
IN
= 4.9V p-p
T = 25C
A
V
= 1
Figure 14. Closed-Loop Output Voltage Swing vs. Frequency
V
S
= 2.5V, 0.9V
A = 100
A = 10
A = 1
04356-0-012
FREQUENCY (Hz)
OUTP
UT IMP
E
DANCE
(
)
100
175
350
1575
1925
1k
100k
1750
1400
1225
875
1050
700
525
10k
Figure 15. Output Impedance vs. Frequency
04356-0-013
FREQUENCY (Hz)
CMRR (dB)
100
60
40
100
140
1k
10k
120
80
60
20
40
0
20
100k
V
S
= 2.5V
Figure 16. Common-Mode Rejection Ratio vs. Frequency
10
100
1k
10k
100k
V
S
= 2.5V
04356-0-014
FREQUENCY (Hz)
P
S
RR (dB)
0
140
40
60
20
20
60
40
80
120
100
Figure 17. PSRR vs. Frequency
Rev. A | Page 7 of 16
AD8603/AD8607/AD8609
LOAD CAPACITANCE (pF)
SM
A
LL SIGN
A
L
OVER
SH
OOT (
%
)
10
0
10
20
60
100
1000
30
OS+
OS
50
40
V
S
= 5V
04356-0-015
Figure 18. Small Signal Overshoot vs. Load Capacitance
TEMPERATURE (C)
S
U
P
P
L
Y
CURRE
NT (
A)
40
35
20
80
25
50
60
10
5
35
65
10
0
95
110 125
25
50
55
45
40
30
20
15
5
04356-0-016
V
S
= 2.5V
Figure 19. Supply Current vs. Temperature
SUPPLY VOLTAGE (V)
S
U
P
P
L
Y
CURRE
NT (
A)
0
0
30
60
80
2.0
4.0
5.0
3.0
20
10
70
50
40
1.0
100
90
04356-0-017
T
A
= 25C
Figure 20. Supply Current vs. Supply Voltage
04356-0-018
V
S
= 5V, 1.8V
TIME (1s/DIV)
VOLTAGE NOISE (
1
V/D
I
V)
Figure 21. 0.1 Hz to 10 Hz Input Voltage Noise
04356-0-019
V
S
= 5V
R
L
= 10k
C
L
= 200pF
A
V
= 1
TIME (4
s/DIV)
VOLTA
GE (
50mV/D
I
V)
Figure 22. Small Signal Transient
04356-0-020
V
S
= 5V
R
L
= 10k
C
L
= 200pF
A
V
= 1
TIME (20
s/DIV)
VOLTA
GE (
1
V/D
I
V)
Figure 23. Large Signal Transient
Rev. A | Page 8 of 16
AD8603/AD8607/AD8609
Rev. A | Page 9 of 16
04356-0-021
V
S
= 2.5V
R
L
= 10k
A
V
= 100
V
IN
= 50mV
0V
0V
50mV
+2.5V
TIME (4
s/DIV))
VOLTA
GE (
50mV/D
IV)
TIME (40
s/DIV))
Figure 24. Negative Overload Recovery
04356-0-022
V
S
= 2.5V
R
L
= 10k
A
V
= 100
V
IN
= 50mV
0V
0V
50mV
+2.5V
TIME (4
s/DIV)
VOLTA
GE (
50mV/D
IV)
Figure 25. Positive Overload Recovery
04356-0-045
FREQUENCY (kHz)
VOLTA
GE N
OISE D
E
N
S
ITY (
n
V/ H
z
)
24
0.1
1.0
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
0
48
72
96
120
144
168
0
V
S
= 2.5V
Figure 26. Voltage Noise Density vs. Frequency
04356-0-046
FREQUENCY (kHz)
VOLTA
GE N
OISE D
E
N
S
ITY (
n
V/ H
z
)
22
1
10
2
3
4
5
6
7
8
9
0
44
66
88
110
132
176
0
V
S
= 2.5V
154
Figure 27. Voltage Noise Density vs. Frequency
V
OS
(
V)
NUMBE
R OF AMP
LIFIE
RS
300
0
300
500
800
240
60
240
180 120
120
180
300
400
200
100
700
600
0
60
50
150
250
350
450
550
650
750
V
S
= 1.8V
T
A
= 25C
V
CM
= 0V to 1.8V
04356-0-025
Figure 28. V
OS
Distribution
V
CM
(V)
V
OS
(
V)
0.0
300
100
100
300
0.9
0.6
0.3
1.5
1.8
1.2
200
150
250
50
0
50
150
200
250
V
S
= 1.8V
T
A
= 25C
04356-0-026
V
CM
(V)
Figure 29. Input Offset Voltage vs. Common-Mode Voltage
AD8603/AD8607/AD8609
LOAD CURRENT (mA)
OU
TPU
T
VOLTA
GE TO SU
PPLY R
A
I
L (
m
V)
0.001
0.01
0.1
10
100
0.01
0.1
1
10
1000
1
SINK
SOURCE
04356-0-027
V
S
= 1.8V
T
A
= 25C
Figure 30. Output Voltage to Supply Rail vs. Load Current
TEMPERATURE (C)
OUTPUT SW
ING (
m
V)
40
0
30
60
5
35
125
20
20
10
50
40
25
04356-0-028
70
80
90
100
10
50
65
80
95
110
V
OL
@ 1mA LOAD
V
DD
V
OH
@ 1mA LOAD
V
S
= 1.8V
Figure 31. Output Voltage Swing vs. Temperature
LOAD CAPACITANCE (pF)
SM
A
LL SIGN
A
L
OVER
SH
OOT (
%
)
10
0
10
20
60
100
1000
30
50
40
V
S
= 1.8V
T
A
= 25C
A
V
= 1
04356-0-029
OS
OS+
Figure 32. Small Signal Overshoot vs. Load Capacitance
1
10
100
1M
10M
V
S
= 0.9V
R
L
= 100k
C
L
= 20pF
= 70
04356-0-030
FREQUENCY (Hz)
PH
A
SE (
D
egree)
OPEN-
L
OOP GAIN (
d
B)
20
80
20
80
100
60
40
0
40
60
100
45
180
45
180
225
135
90
0
90
135
225
Figure 33. Open-Loop Gain and Phase vs. Frequency
100
1k
10k
100k
V
S
= 1.8V
04356-0-031
CMRR (dB)
60
40
20
120
140
100
80
40
0
20
60
FREQUENCY (Hz)
Figure 34. Common-Mode Rejection Ratio vs. Frequency
0.01
0.1
1
100
10
FREQUENCY (kHz)
OUTPUT SW
ING (
V
P-P
)
0.0
0.9
1.8
0.6
0.3
1.5
1.2
04356-0-032
V
S
= 1.8V
V
IN
= 1.7V pp
T= 25C
A
V
= 1
Figure 35. Closed-Loop Output Voltage Swing vs. Frequency
Rev. A | Page 10 of 16
AD8603/AD8607/AD8609
Rev. A | Page 11 of 16
04356-0-033
V
S
= 1.8V
R
L
= 10k
C
L
= 200pF
A
V
= 1
VOLTA
GE (
50mV/D
IV)
TIME (4
s/DIV)
Figure 36. Small Signal Transient
VS = 1.8V
RL = 10k
C
L
= 200pF
A
V
= 1
04356-0-034
VOLTA
GE (
500mV/D
IV)
TIME (20
s/DIV)
Figure 37. Large Signal Transient
04356-0-047
FREQUENCY (kHz)
VOLTA
GE N
OISE D
E
N
S
ITY (
n
V/ H
z
)
28
0.1
1.0
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
0
56
84
112
140
168
0
V
S
= 0.9V
Figure 38. Voltage Noise Density
04356-0-048
FREQUENCY (kHz)
VOLTA
GE N
OISE D
E
N
S
ITY (
n
V/ H
z
)
22
1
10
2
3
4
5
6
7
8
9
0
44
66
88
110
132
176
0
V
S
= 0.9V
154
Figure 39. Voltage Noise Density
FREQUENCY (Hz)
CHANNEL SEPARATION (dB)
100
120
40
20
0
1k
10k
100k
1M
60
140
80
100
04356-A-043
V
S
= 2.5V, 0.9V
Figure 40. Channel Separation
AD8603/AD8607/AD8609
Rev. A | Page 12 of 16
APPLICATIONS
NO PHASE REVERSAL
The AD8603/AD8607/AD8609 do not exhibit phase inversion
even when the input voltage exceeds the maximum input
common-mode voltage. Phase reversal can cause permanent
damage to the amplifier, resulting in system lockups. The
AD8603/AD8607/AD8609 can handle voltages of up to 1 V
over the supply.
04356-0-037
VOLTA
GE (
1
V/D
IV)
TIME (4
s/DIV)
V
S
= 2.5V
V
IN
= 6V p-p
A
V
= 1
R
L
= 10k
V
IN
V
OUT
Figure 41. No Phase Response
INPUT OVERVOLTAGE PROTECTION
If a voltage 1 V higher than the supplies is applied at either
input, the use of a limiting series resistor is recommended. If
both inputs are used, each one should be protected with a series
resistor.
To ensure good protection, the current should be limited to a
maximum of 5 mA. The value of the limiting resistor can be
determined from the equation
(V
IN
V
S
)/(R
S
+ 200 ) 5 mA
DRIVING CAPACITIVE LOADS
The AD8603/AD8607/AD8609 are capable of driving large
capacitive loads without oscillating. Figure 42 shows the output
of the AD8603/AD8607/AD8609 in response to a 100 mV input
signal, with a 2 nF capacitive load.
Although it is configured in positive unity gain (the worst case),
the AD8603 shows less than 20% overshoot. Simple additional
circuitry can eliminate ringing and overshoot.
One technique is the snubber network, which consists of a
series RC and a resistive load (see Figure 43). With the snubber
in place, the AD8603/AD8607/AD8609 are capable of driving
capacitive loads of 2 nF with no ringing and less than 3%
overshoot.
The use of the snubber circuit is usually recommended for unity
gain configurations. Higher gain configurations help improve
the stability of the circuit. Figure 44 shows the same output
response with the snubber in place.
04356-0-038
V
S
= 0.9V
V
IN
= 100mV
C
L
= 2nF
R
L
= 10k
Figure 42. Output Response to a 2 nF Capacitive Load, without Snubber
C
S
47pF
V
CC
V
EE
R
S
150
200mV
C
L
V+
V
+
04356-A-039
Figure 43. Snubber Network
04356-0-040
V
SY
= 0.9V
V
IN
= 100mV
C
L
= 2nF
R
L
= 10k
R
S
= 150
C
S
= 470pF
Figure 44. Output Response to a 2 nF Capacitive Load, with Snubber
Optimum values for R
S
and C
S
are determined empirically;
Table 5 lists a few starting values.
Table 5. Optimum Values for the Snubber Network
C
L
(pF)
R
S
()
C
S
(pF)
100~500 500
680
1500 100 330
1600~2000 400
100
AD8603/AD8607/AD8609
Rev. A | Page 13 of 16
PROXIMITY SENSORS
Proximity sensors can be capacitive or inductive and are used in
a variety of applications. One of the most common applications
is liquid level sensing in tanks. This is particularly popular in
pharmaceutical environments where a tank must know when to
stop filling or mixing a given liquid. In aerospace applications,
these sensors detect the level of oxygen used to propel engines.
Whether in a combustible environment or not, capacitive
sensors generally use low voltage. The precision and low voltage
of the AD8603/AD8607/AD8609 make the parts an excellent
choice for such applications.
COMPOSITE AMPLIFIERS
A composite amplifier can provide a very high gain in
applications where high closed-loop dc gains are needed. The
high gain achieved by the composite amplifier comes at the
expense of a loss in phase margin. Placing a small capacitor, C
F
,
in the feedback in parallel with R2 (Figure 45) improves the
phase margin. Picking C
F
= 50 pF yields a phase margin of
about 45 for the values shown in Figure 45.
A composite amplifier can be used to optimize dc and ac
characteristics. Figure 46 shows an example using the AD8603
and the AD8541. This circuit offers many advantages. The
bandwidth is increased substantially, and the input offset
voltage and noise of the AD8541 become insignificant since
they are divided by the high gain of the AD8603.
The circuit of Figure 46 offers a high bandwidth (nearly double
that of the AD8603), a high output current, and a very low
power consumption of less than 100 A.
V
EE
V
CC
R1
1k
V
CC
V
EE
V
IN
99k
R2
AD8603
AD8541
V+
V
V+
V
04356-A-041
R3
R4
99k
1k
U5
Figure 45. High Gain Composite Amplifier
R1
1k
V+
V
V+
V
V
IN
100k
R2
AD8603
04356-A-042
AD8541
100
C3
1k
R4
R3
C2
V
CC
V
EE
V
CC
V
EE
Figure 46. Low Power Composite Amplifier
AD8603/AD8607/AD8609
BATTERY-POWERED APPLICATIONS
network at the output to reduce the noise. The signal bandwidth
can be calculated by R2C2 and the closed-loop bandwidth is
the intersection point of the open-loop gain and the noise gain.
The AD8603/AD8607/AD8609 are ideal for battery-powered
applications. The parts are tested at 5 V, 3.3 V, 2.7 V, and 1.8 V
and are suitable for various applications whether in single or
dual supply.
The circuit shown in Figure 47 has a closed-loop bandwidth of
58 kHz and a signal bandwidth of 16 Hz. Increasing C2 to 50 pF
yields a closed-loop bandwidth of 65 kHz, but only 3.2 Hz of
signal bandwidth can be achieved.
In addition to their low offset voltage and low input bias, the
AD8603/AD8607/AD8609 have a very low supply current of
40 A, making the parts an excellent choice for portable
electronics. The TSOT package allows the AD8603 to be used
on smaller board spaces.
PHOTODIODES
Photodiodes have a wide range of applications from bar code
scanners to precision light meters and CAT scanners. The very
low noise and low input bias current of the AD8603/AD8607/
AD8609 make the parts very attractive amplifiers for I-V
conversion applications.
Figure 47
Figure 47. Photodiode Circuit
VEE
VCC
C2 10pF
R2 1000M
R1
1000M
AD8603
C1
10pF
04356-0-044
shows a simple photodiode circuit. The feedback
capacitor helps the circuit maintain stability. The signal
bandwidth can be increased at the expense of an increase in the
total noise; a low-pass filter can be implemented by a simple RC
Rev. A | Page 14 of 16
AD8603/AD8607/AD8609
OUTLINE DIMENSIONS
0.25 (0.0098)
0.17 (0.0067)
1.27 (0.0500)
0.40 (0.0157)
0.50 (0.0196)
0.25 (0.0099)
45
8
0
1.75 (0.0688)
1.35 (0.0532)
SEATING
PLANE
0.25 (0.0098)
0.10 (0.0040)
4
1
8
5
5.00 (0.1968)
4.80 (0.1890)
4.00 (0.1574)
3.80 (0.1497)
1.27 (0.0500)
BSC
6.20 (0.2440)
5.80 (0.2284)
0.51 (0.0201)
0.31 (0.0122)
COPLANARITY
0.10
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN
COMPLIANT TO JEDEC STANDARDS MS-012AA
Figure 48. 8-Lead Standard Small Outline Package (SOIC) [R-8]
Dimensions shown in millimeters and (inches)
PIN 1
1.60 BSC
2.80 BSC
1.90
BSC
0.95 BSC
1
3
4
5
2
0.20
0.08
0.60
0.45
0.30
8
4
0.50
0.30
0.10 MAX
SEATING
PLANE
1.00 MAX
0.90
0.87
0.84
COMPLIANT TO JEDEC STANDARDS MO-193AB
2.90 BSC
Figure 49. 5-Lead Thin Small Outline Transistor Package [TSOT]
(UJ-5)
Dimensions in millimeters
0.80
0.60
0.40
8
0
4
8
5
4.90
BSC
PIN 1
0.65 BSC
3.00
BSC
SEATING
PLANE
0.15
0.00
0.38
0.22
1.10 MAX
3.00
BSC
COPLANARITY
0.10
0.23
0.08
COMPLIANT TO JEDEC STANDARDS MO-187AA
Figure 50. 8-Lead MSOP Package (RM-8)
Dimensions in millimeters
Rev. A | Page 15 of 16
AD8603/AD8607/AD8609
Rev. A | Page 16 of 16
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN
COPLANARITY
0.10
14
8
7
1
6.20 (0.2441)
5.80 (0.2283)
4.00 (0.1575)
3.80 (0.1496)
8.75 (0.3445)
8.55 (0.3366)
1.27 (0.0500)
BSC
SEATING
PLANE
0.25 (0.0098)
0.10 (0.0039)
0.51 (0.0201)
0.31 (0.0122)
1.75 (0.0689)
1.35 (0.0531)
8
0
0.50 (0.0197)
0.25 (0.0098)
1.27 (0.0500)
0.40 (0.0157)
0.25 (0.0098)
0.17 (0.0067)
COMPLIANT TO JEDEC STANDARDS MS-012AB
45
Figure 51. 14-Lead Standard Small Outline Package (SOIC) [R-14]
Dimensions shown in millimeters and (inches)
4.50
4.40
4.30
14
8
7
1
6.40
BSC
PIN 1
5.10
5.00
4.90
0.65
BSC
SEATING
PLANE
0.15
0.05
0.30
0.19
1.20
MAX
1.05
1.00
0.80
0.20
0.09
8
0
0.75
0.60
0.45
COPLANARITY
0.10
COMPLIANT TO JEDEC STANDARDS MO-153AB-1
Figure 52. 14-Lead Thin Shrink Small Outline Package (TSSOP) [RU-14]
Dimensions shown in millimeters
ORDERING GUIDE
Model
Temperature Range
Package Description Package
Option
Branding
AD8603AUJ-R2
40C to +125C
5-Lead TSOT-23
UJ-5
BFA
AD8603AUJ-REEL
40C to +125C
5-Lead TSOT-23
UJ-5
BFA
AD8603AUJ-REEL7
40C to +125C
5-Lead TSOT-23
UJ-5
BFA
AD8607ARM-R2
40C to +125C
8-Lead MSOP
RM-8
A00
AD8607ARM-REEL
40C to +125C
8-Lead MSOP
RM-8
A00
AD8607AR
40C to +125C
8-Lead SOIC
R-8
AD8607AR-REEL
40C to +125C
8-Lead SOIC
R-8
AD8607AR-REEL7
40C to +125C
8-Lead SOIC
R-8
AD8609AR
40C to +125C
14-Lead SOIC
R-14
AD8609AR-REEL
40C to +125C
14-Lead SOIC
R-14
AD8609AR-REEL7
40C to +125C
14-Lead SOIC
R-14
AD8609ARU
40C to +125C
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