CONNECTION DIAGRAM
Plastic Mini-DIP (N)
Cerdip (Q) and
Plastic SOIC (R) Packages
REV. B
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.
a
Dual Precision, 500 ns
Settling, BiFET Op Amp
AD746
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700
Fax: 617/326-8703
FEATURES
AC PERFORMANCE
500 ns Settling to 0.01% for 10 V Step
75 V/ s Slew Rate
0.0001% Total Harmonic Distortion (THD)
13 MHz Gain Bandwidth
Internal Compensation for Gains of +2 or Greater
DC PERFORMANCE
0.5 mV max Offset Voltage (AD746B)
10 V/ C max Drift (AD746B)
175 V/mV min Open Loop Gain (AD746B)
2 V p-p Noise, 0.1 Hz to 10 Hz
Available in Plastic Mini-DIP, Cerdip and Surface
Mount Packages
Available in Tape and Reel in Accordance with
EIA-481A Standard
MIL-STD-883B Processing also Available
Single Version: AD744
APPLICATIONS
Dual Output Buffers for 12- and 14-Bit DACs
Input Buffers for Precision ADCs, Wideband
Preamplifiers and Low Distortion Audio Circuitry
PRODUCT DESCRIPTION
The AD746 is a dual operational amplifier, consisting of two
AD744 BiFET op amps on a single chip. These precision
monolithic op amps offer excellent dc characteristics plus rapid
settling times, high slew rates and ample bandwidths. In
addition, the AD746 provides the close matching ac and dc
characteristics inherent to amplifiers sharing the same
monolithic die.
The single pole response of the AD746 provides fast settling:
500 ns to 0.01%. This feature, combined with its high dc
precision, makes it suitable for use as a buffer amplifier for 12-
or 14-bit DACs and ADCs. Furthermore, the AD746's low total
harmonic distortion (THD) level of 0.0001% and very close
matching ac characteristics make it an ideal amplifier for many
demanding audio applications.
The AD746 is internally compensated for stable operation as a
unity gain inverter or as a noninverting amplifier with a gain of 2
or greater. It is available in four performance grades. The
AD746J is rated over the commercial temperature range of 0 to
+70
C. The AD746A and AD746B are rated over the industrial
temperature range of 40
C to +85
C. The AD746S is rated
over the military temperature range of 55
C to +125
C and is
available processed to MIL-STD-883B, Rev. C.
The AD746 is available in three 8-pin packages: plastic mini
DIP, hermetic cerdip and surface mount (SOIC).
PRODUCT HIGHLIGHTS
1. The AD746 offers exceptional dynamic response for high
speed data acquisition systems. It settles to 0.01% in 500 ns
and has a 100% tested minimum slew rate of 50 V/
s
(AD746B).
2. Outstanding dc precision is provided by a combination of
Analog Devices' advanced processing technology, laser wafer
drift trimming and well-matched ion-implanted JFETs. Input
offset voltage, input bias current and input offset current are
specified in the warmed-up condition and are 100% tested.
3. Differential and multichannel systems will benefit from the
AD746's very close matching of ac characteristics. Input
offset voltage specs are fully tested and guaranteed to a
maximum of 0.5 mV (AD746B).
4. The AD746 has very close, guaranteed matching of input
bias current between its two amplifiers.
5. Unity gain stable version AD712 also available.
REV. B
2
AD746SPECIFICATIONS
(@ +25 C and 15 V dc, unless otherwise noted)
AD746J/A
AD746B
AD746S
Model
Conditions
Min
Typ
Max
Min
Typ
Max
Min
Typ
Max Units
INPUT OFFSET VOLTAGE
1
Initial Offset
0.3
1.5
0.25
0.5
0.3
1.0
mV
Offset
T
MIN
to T
MAX
2.0
0.7
1.5
mV
vs. Temperature
12
20
5
10
12
20
V/
C
vs. Supply
2
(PSRR)
80
95
84
100
80
95
dB
vs. Supply (PSRR)
T
MIN
to T
MAX
80
84
80
dB
Long Term Stability
15
15
15
V/month
INPUT BIAS CURRENT
3
Either Input
V
CM
= 0 V
110
250
110
150
110
250
pA
Either Input @ T
MAX
V
CM
= 0 V
2.5/7
5.7/16
7
9.6
113
256
nA
Either Input
V
CM
= +10 V
145
350
145
200
145
350
pA
Offset Current
V
CM
= 0 V
45
125
45
75
45
125
pA
Offset Current @ T
MAX
V
CM
= 0 V
1.0/3
2.8/8
3
4.8
45
128
nA
MATCHING CHARACTERISTICS
Input Offset Voltage
0.6
1.5
0.3
0.5
0.6
1.0
mV
Input Offset Voltage
T
MIN
to T
MAX
2.0
0.7
1.5
mV
Input Offset Voltage Drift
20
20
20
V/
C
Input Bias Current
125
75
125
pA
Crosstalk
@ 1 kHz
120
120
120
dB
@ 100 kHz
90
90
90
dB
FREQUENCY RESPONSE
Gain BW, Small Signal
G = 1
8
13
9
13
8
13
MHz
Slew Rate, Unity Gain
G = 1
45
75
50
75
45
75
V/
s
Full Power Response
V
O
= 20 V p-p
600
600
600
kHz
Settling Time to 0.01%
4
G = 1
0.5
0.75
0.5
0.75
0.5
0.75
s
Total Harmonic
f = 1 kHz
Distortion
R1
2 k
V
O
= 3 V rms
0.0001
0.0001
0.0001
%
INPUT IMPEDANCE
Differential
2.5
l0
1l
5.5
2.5
l0
1l
5.5
2.5
l0
1l
5.5
pF
Common Mode
2.5
l0
1l
5.5
2.5
l0
1l
5.5
2.5
l0
1l
5.5
pF
INPUT VOLTAGE RANGE
Differential
5
20
20
20
V
Common-Mode Voltage
+14.5, 11.5
+14.5, 11.5
+14.5, 11.5
V
Over Max Operating Range
6
11
+13
11
+13
11
+13
V
Common-Mode Rejection Ratio
V
CM
=
10 V
78
88
82
88
78
88
dB
T
MIN
to T
MAX
76
84
80
84
76
84
dB
V
CM
=
11 V
72
84
78
84
72
84
dB
T
MIN
to T
MAX
70
80
74
80
70
80
dB
INPUT VOLTAGE NOISE
0.1 to 10 Hz
2
2
2
V p-p
f = 10 Hz
45
45
45
nV/ Hz
f = 100 Hz
22
22
22
nV/ Hz
f = 1 kHz
18
18
18
nV/ Hz
f = 10 kHz
16
16
16
nV/ Hz
INPUT CURRENT NOISE
f = 1 kHz
0.01
0.01
0.01
pA/ Hz
OPEN LOOP GAIN
V
O
=
10 V
R1
2 k
150
300
175
300
150
300
V/mV
T
MIN
to T
MAX
75
200
75
200
65
175
V/mV
OUTPUT CHARACTERISTICS
Voltage
R1
2 k
+13, 12.5
+13.9, 13.3
+13, 12.5
+13.9, 13.3
+13, 12.5
+13.9, 13.3
V
T
MIN
to T
MAX
12
+13.8, 13.1
12
+13.8, 13.1
12
+13.8, 13.1
V
Current
Short Circuit
25
25
25
mA
Max Capacitive Load
Gain = 1
50
50
50
pF
Driving Capability
Gain = 10
500
500
500
pF
POWER SUPPLY
Rated Performance
15
15
15
V
Operating Range
4.5
18
4.5
18
4.5
18
V
Quiescent Current
7
10
7
8.0
7
10
mA
TEMPERATURE RANGE
Rated Performance
0 to +70/40 to +85
40 to +85
55 to +125
C
PACKAGE OPTIONS
8-Pin Plastic Mini-DIP (N-8)
AD746JN
8-Pin Cerdip (Q-8)
AD746AQ
AD746BQ
AD746SQ
8-Pin Surface Mount (R-8)
AD746JR
Tape and Reel
AD746JR-REEL
Chips
AD746SCHIPS
TRANSISTOR COUNT
54
54
54
NOTES
1
Input Offset Voltage specifications are guaranteed after 5 minutes of operation at T
A
= +25
C.
2
PSRR test conditions: +V
S
= 15 V, V
S
= 12 V to 18 V and +V
S
= 12 V to 18 V, V
S
= 15 V.
3
Bias Current Specifications are guaranteed maximum at either input after 5 minutes of operation at T
A
= +25
C. For higher temperature, the current doubles every
10
C.
4
Gain = 1, Rl = 2 k, Cl = 10 pF.
5
Defined as voltage between inputs, such that neither exceeds
10 V from ground.
6
Typically exceeding 14.1 V negative common-mode voltage on either input results in an output phase reversal.
Specifications subject to change without notice.
Specifications in boldface are tested on all production units at final electrical test. Results from those tests are used to calculate outgoing quality levels. All min and
max specifications are guaranteed, although only those shown in boldface are tested on all production units.
ABSOLUTE MAXIMUM RATINGS
1
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18 V
Internal Power Dissipation
2
. . . . . . . . . . . . . . . . . . . . . 500 mW
Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
V
S
Output Short Circuit Duration
(For One Amplifier) . . . . . . . . . . . . . . . . . . . . . . . Indefinite
Differential Input Voltage . . . . . . . . . . . . . . . . . . +V
S
and V
S
Storage Temperature Range (Q) . . . . . . . . . . 65
C to +150
C
Storage Temperature Range (N, R) . . . . . . . . 65
C to +125
C
Operating Temperature Range
AD746J . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0
C to +70
C
AD746A/B . . . . . . . . . . . . . . . . . . . . . . . . . . 40
C to +85
C
AD746S . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
C to +125
C
Lead Temperature Range
(Soldering 60 seconds) . . . . . . . . . . . . . . . . . . . . . . . +300
C
ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
NOTES
1
Stresses above those listed under "Absolute Maximum Ratings" may cause
permanent damage to the device. This is a stress rating only and 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.
2
8-Pin Plastic Package:
JA
= 100
C/Watt,
JC
= 50
C/Watt
8-Pin Cerdip Package:
JA
= 110
C/Watt,
JC
= 30
C/Watt
8-Pin Small Outline Package:
JA
= 160
C/Watt,
JC
= 42
C/Watt
METALIZATION PHOTOGRAPH
Contact factory for latest dimensions.
Dimensions shown in inches and (mm).
WARNING!
ESD SENSITIVE DEVICE
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 AD746 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.
AD746
REV. B
3
AD746
4
REV. B
Typical Characteristics
Figure 1. Input Voltage Swing vs.
Supply Voltage
Figure 4. Quiescent Current vs.
Supply Voltage
Figure 7. Input Bias Current vs.
Common Mode Voltage
Figure 2. Output Voltage Swing
vs. Supply Voltage
Figure 5. Input Bias Current vs.
Temperature
Figure 8. Short Circuit Current
Limit vs. Temperature
Figure 3. Output Voltage Swing
vs. Load Resistance
.
Figure 6. Output Impedance vs.
Frequency
Figure 9. Gain Bandwidth Product
vs. Temperature
AD746
REV. B
5
Figure 12. Open Loop Gain vs.
Supply Voltage
Figure 15. Output Swing and
Error vs. Settling Time
Figure 18. Slew Rate vs. Input
Error Signal
Figure 11. Settling Time vs.
Closed Loop Voltage Gain
Figure 14. Large Signal Frequency
Response
Figure 17. Input Noise Voltage
Spectral Density
Figure 10. Open Loop Gain and
Phase Margin vs. Frequency
Figure 13. Common-Mode and
Power Supply Rejection vs.
Frequency
Figure 16. Total Harmonic
Distortion vs. Frequency Using
Circuit of Figure 19
AD746
6
REV. B
POWER SUPPLY BYPASSING
The power supply connections to the AD746 must maintain a
low impedance to ground over a bandwidth of 13 MHz or more.
This is especially important when driving a significant resistive
or capacitive load, since all current delivered to the load comes
from the power supplies. Multiple high quality bypass capacitors
are recommended for each power supply line in any critical
application. A 0.1
F ceramic and a 1
F tantalum capacitor as
shown in Figure 20 placed as close as possible to the amplifier
(with short lead lengths to power supply common) will assure
adequate high frequency bypassing, in most applications. A
minimum bypass capacitance of 0.1
F should be used for any
application.
If only one of the two amplifiers inside the AD746 is to be
utilized, the unused amplifier should be connected as shown in
Figure 21a. Note that the noninverting input should be
grounded and that R
L
and C
L
are not required.
Figure 19. THD Test Circuit
Figure 22a. Unity Gain Inverter
Figure 21a. Gain of 2 Follower
Figure 21b. Gain of 2 Follower
Large Signal Pulse Response
Figure 21c. Gain of 2 Follower
Small Signal Pulse Response
Figure 22b. Unity Gain Inverter
Large Signal Pulse Response
Figure 22c. Unity Gain Inverter
Small Signal Pulse Response
Figure 20. Power Supply
Bypassing
AD746
REV. B
7
Table I. Performance Summary for the 3 Op Amp
Instrumentation Amplifier Circuit
T
SETTLE
Gain
R
G
Bandwidth
(0.01%)
2
20 k
2.5 MHz
1.0
s
10
4.04 k
1 MHz
2.0
s
100
404
290 kHz
5.0
s
Figure 25. Settling Time of the 3 Op
Amp Instrumentation Amplifier.
Gain = 10, Horizontal Scale: 0.5
s/Div,
Vertical Scale: 5 V/Div.
Error Signal Scale: 0.01%/Div.
THD Performance Considerations
The AD746 was carefully optimized to offer excellent
performance in terms of total harmonic distortion (THD) in
signal processing applications. The THD level when operating
the AD746 in inverting gain applications will show a gradual
rise from the distortion floor of 20 dB/decade (see Figure 28).
In noninverting applications, care should be taken to balance
the source impedances at both the inverting and noninverting
inputs, to avoid distortion caused by the modulation of input
capacitance inherent in all BiFET op amps.
Figure 26. THD Measurement, Inverter Circuit
Figure 27. THD Measurement, Follower Circuit
A HIGH SPEED 3 OR AMP INSTRUMENTATION
AMPLIFIER CIRCUIT
The instrumentation amplifier circuit shown in Figure 23 can
provide a range of gains from 2 up to 1000 and higher. The
circuit bandwidth is 2.5 MHz at a gain of 2 and 750 kHz at a
gain of 10; settling time for the entire circuit is less than 2
s to
within 0.01% for a 10 volt step, (G = 10).
Figure 23. A High Performance, 3 Op Amp, Instrumenta-
tion Amplifier Circuit
Figure 24. Pulse Response of the 3
Op Amp Instrumentation Amplifier.
Gain = 10, Horizontal Scale:
0.5
s/Div, Vertical Scale: 5 V/Div.
AD746
8
REV. B
C1319109/89
PRINTED IN U.S.A.
Figure 28. THD vs. Frequency Using Standard Distortion
Analyzer
20k
2.21k
2k
2k
SINE WAVE
GENERATOR
20V p-p
OUTPUT
LEVEL
20V p-p
1
2
3
4
V
OUT
#1
+
1/2
AD746
+
V
S
1
F
0.1
F
7
6
5
8
+
1/2
AD746
V
OUT
#2
+V
S
+
1
F
0.1
F
CROSSTALK = 20 LOG
10
V
OUT
#1
V
OUT
#2
+ 20dB
Figure 29. Crosstalk Test Circuit
Figure 30. Crosstalk vs. Frequency
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
Mini-DIP (N) Package
Cerdip (Q) Package
Plastic Small Outline
(R) Package
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