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FEATURES
ULTRALOW NOISE PERFORMANCE
2.9 nV/
Hz
at 10 kHz
0.38 V p-p, 0.1 Hz to 10 Hz
6.9 fA/
Hz
Current Noise at 1 kHz
EXCELLENT AC PERFORMANCE
12.5 V/ s Slew Rate
20 MHz Gain Bandwidth Product
THD = 0.0002% @ 1 kHz
Internally Compensated for Gains of +5 (or –4) or
Greater
EXCELLENT DC PERFORMANCE
0.5 mV Max Offset Voltage
250 pA Max Input Bias Current
2000 V/mV Min Open Loop Gain
Available in Tape and Reel in Accordance with
EIA-481A Standard
APPLICATIONS
Sonar
Photodiode and IR Detector Amplifiers
Accelerometers
Low Noise Preamplifiers
High Performance Audio
Ultralow Noise,
High Speed, BiFET Op Amp
AD745
CONNECTION DIAGRAM
16-Lead SOIC (R) Package
amplifier for high-speed applications demanding low noise and
high dc precision. Furthermore, the AD745 does not exhibit an
output phase reversal.
The AD745 also has excellent dc performance with 250 pA
maximum input bias current and 0.5 mV maximum offset voltage.
The internal compensation of the AD745 is optimized for higher
gains, providing a much higher bandwidth and a faster slew
rate. This makes the AD745 especially useful as a preamplifier
where low level signals require an amplifier that provides both
high amplification and wide bandwidth at these higher gains.
The AD745 is available in two performance grades. The AD745J
and AD745K are rated over the commercial temperature range
of 0°C to 70°C, and are available in the 16-lead SOIC package.
120
120
PRODUCT DESCRIPTION
The AD745 is an ultralow noise, high-speed, FET input opera-
tional amplifier. It offers both the ultralow voltage noise and
high speed generally associated with bipolar input op amps and
the very low input currents of FET input devices. Its 20 MHz
bandwidth and 12.5 V/µs slew rate makes the AD745 an ideal
1000
R
SOURCE
INPUT NOISE VOLTAGE – nV/ Hz
E
O
100
R
SOURCE
OP37 AND
RESISTOR
100
PHASE
80
60
GAIN
40
20
0
100
80
60
40
AD745 AND RESISTOR
OR
OP37 AND RESISTOR
10
AD745 AND
RESISTOR
20
0
–20
100M
RESISTOR NOISE ONLY
1
100
1k
10k
100k
SOURCE RESISTANCE –
1M
10M
–20
100
1k
10k
100k
1M
FREQUENCY – Hz
10M
Figure 1.
Figure 2.
REV. D
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. 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
www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 2002
PHASE MARGIN – Degrees
OPEN-LOOP GAIN – dB
AD745–SPECIFICATIONS
AD745 ELECTRICAL CHARACTERISTICS
Model
Conditions
INPUT OFFSET VOLTAGE
1
Initial Offset
Initial Offset
vs. Temp.
vs. Supply (PSRR)
vs. Supply (PSRR)
INPUT BIAS CURRENT
3
Either Input
Either Input
@ T
MAX
Either Input
Either Input, V
S
=
±
5 V
INPUT OFFSET CURRENT
Offset Current
@ T
MAX
FREQUENCY RESPONSE
Gain BW, Small Signal
Full Power Response
Slew Rate
Settling Time to 0.01%
Total Harmonic
Distortion
4
INPUT IMPEDANCE
Differential
Common Mode
INPUT VOLTAGE RANGE
Differential
5
Common-Mode Voltage
Over Max Operating Range
6
Common-Mode
Rejection Ratio
INPUT VOLTAGE NOISE
Min
(@ +25 C and
AD745J
Typ
0.25
15 V dc, unless otherwise noted.)
Max
1.0
1.5
100
98
400
8.8
600
200
150
2.2
Min
AD745K
Typ
0.1
2
106
105
150
250
5.5
400
125
75
1.1
20
120
12.5
5
0.0002
1
×
10
10
20
3
×
10
11
18
±
20
+13.3, –10.7
+12
–10
90
88
102
0.38
5.5
3.6
3.2
2.9
6.9
2000
1800
4000
1200
+13, –12
1.0
10.0
6.0
5.0
4.0
+12
nA
pA
pA
pA
nA
MHz
kHz
V/µs
µs
%
Ω
pF
Ω
pF
V
V
V
dB
dB
µV
p-p
nV/√Hz
nV/√Hz
nV/√Hz
nV/√Hz
fA/√Hz
V/mV
V/mV
V/mV
V
+13.6, –12.6
+12, –10
+13.8, –13.1
40
±
15
8
50
V
V
V
mA
V
V
mA
Max
0.5
1.0
Unit
mV
mV
µV/°C
dB
dB
pA
T
MIN
to T
MAX
T
MIN
to T
MAX
12 V to 18 V
2
T
MIN
to T
MAX
V
CM
= 0 V
V
CM
= 0 V
V
CM
= +10 V
V
CM
= 0 V
V
CM
= 0 V
V
CM
= 0 V
G = –4
V
O
= 20 V p-p
G = –4
f = 1 kHz
G = –4
90
88
2
96
150
250
30
40
250
30
30
20
120
12.5
5
0.0002
1
×
10
10
20
3
×
10
11
18
±
20
+13.3, –10.7
–10
V
CM
=
±
10 V
T
MIN
to T
MAX
0.1 to 10 Hz
f = 10 Hz
f = 100 Hz
f = 1 kHz
f = 10 kHz
f = 1 kHz
V
O
=
±
10 V
R
LOAD
≥
2 kΩ
T
MIN
to T
MAX
R
LOAD
= 600
Ω
R
LOAD
≥
600
Ω
R
LOAD
≥
600
Ω
T
MIN
to T
MAX
R
LOAD
≥
2 kΩ
Short Circuit
80
78
95
0.38
5.5
3.6
3.2
2.9
6.9
5.0
4.0
INPUT CURRENT NOISE
OPEN LOOP GAIN
1000
800
4000
1200
OUTPUT CHARACTERISTICS
Voltage
+13, –12
+13.6, –12.6
+12, –10
±
12
20
+13.8, –13.1
40
±
15
8
Current
POWER SUPPLY
Rated Performance
Operating Range
Quiescent Current
TRANSISTOR COUNT
20
±
4.8
# of Transistors
±
18
10.0
±
4.8
±
18
10.0
50
NOTES
1
Input offset voltage specifications are guaranteed after five minutes of operations at T
A
= 25°C.
2
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 five minutes of operation at T
A
= 25°C. For higher temperature, the current doubles every 10°C.
4
Gain = –4, R
L
= 2 kΩ, C
L
= 10 pF.
5
Defined as voltage between inputs, such that neither exceeds
±
10 V from common.
6
The AD745 does not exhibit an output phase reversal when the negative common-mode limit is exceeded.
All min and max specifications are guaranteed.
Specifications subject to change without notice.
–2–
REV. D
AD745
ABSOLUTE MAXIMUM RATINGS
1
ESD SUSCEPTIBILITY
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
±
18 V
Internal Power Dissipation
2
SOIC Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 W
Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
±
V
S
Output Short-Circuit Duration . . . . . . . . . . . . . . . . Indefinite
Differential Input Voltage . . . . . . . . . . . . . . . . . . +V
S
and –V
S
Storage Temperature Range (R) . . . . . . . . . –65°C to +125°C
Operating Temperature Range
AD745J/K . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to 70°C
Lead Temperature Range (Soldering 60 sec) . . . . . . . . . 300°C
NOTES
1
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 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
16-Pin Plastic SOIC Package:
θ
JA
= 100°C/W,
θ
JC
= 30°C/W
An ESD classification per method 3015.6 of MIL-STD-883C
has been performed on the AD745, which is a class 1 device.
Using an IMCS 5000 automated ESD tester, the two null pins
will pass at voltages up to 1,000 volts, while all other pins will
pass at voltages exceeding 2,500 volts.
ORDERING GUIDE
Model
AD745JR-16
AD745KR-16
*
Temperature Range
0°C to 70°C
0°C to 70°C
Package
Option
*
R-16
R-16
R = Small Outline IC.
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 AD745 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.
WARNING!
ESD SENSITIVE DEVICE
REV. D
–3–
AD745 –Typical Performance Characteristics
20
R
LOAD
= 10k
(@ + 25 C, V
S
=
15 V, unless otherwise noted.)
35
20
R
LOAD
= 10k
OUTPUT VOLTAGE SWING – V p-p
30
25
20
15
10
5
0
10
INPUT VOLTAGE SWING – V
15
+V
IN
10
–V
IN
5
INPUT VOLTAGE SWING – V
15
POSITIVE
SUPPLY
10
NEGATIVE
SUPPLY
5
0
0
5
10
SUPPLY VOLTAGE
15
VOLTS
20
0
0
5
10
SUPPLY VOLTAGE
15
VOLTS
20
100
1k
LOAD RESISTANCE –
10k
TPC 1. Input Voltage Swing vs.
Supply Voltage
TPC 2. Output Voltage Swing vs.
Supply Voltage
TPC 3. Output Voltage Swing vs.
Load Resistance
12
10
–6
INPUT BIAS CURRENT – Amps
200
100
QUIESCENT CURRENT – mA
10
–7
OUTPUT IMPEDANCE –
10
–8
10
–9
10
–10
10
–11
10
–12
–60 –40 –20
0.01
10k
10
9
6
1
CLOSED LOOP GAIN = –5
0.1
3
0
0
5
10
SUPPLY VOLTAGE
15
VOLTS
20
0 20 40 60 80 100 120 140
TEMPERATURE – C
100k
1M
10M
FREQUENCY – Hz
100M
TPC 4. Quiescent Current vs.
Supply Voltage
TPC 5. Input Bias Current vs.
Temperature
TPC 6. Output Impedance vs.
Frequency
300
10
–6
28
GAIN BANDWIDTH PRODUCT – MHz
0 20 40 60 80 100 120 140
TEMPERATURE – C
INPUT BIAS CURRENT – Amps
INPUT BIAS CURRENT – pA
10
–7
10
–8
10
–9
10
–10
10
–11
10
–12
–60 –40 –20
26
24
22
20
18
16
14
–60 –40 –20
200
100
0
–12
–9
–6
–3
0
3
6
9
COMMON-MODE VOLTAGE – V
12
0 20 40 60 80 100 120 140
TEMPERATURE – C
TPC 7. Input Bias Current vs.
Common-Mode Voltage
TPC 8. Short Circuit Current Limit vs.
Temperature
TPC 9. Gain Bandwidth Product vs.
Temperature
–4–
REV. D
