Analog Devices AD745 Datasheet

Ultralow Noise,

FREQUENCY – Hz

OPEN-LOOP GAIN – dB

PHASE MARGIN – Degrees

120

100

80

60

40

20

0

–20

100 1k 10k 100k 1M

10M 100M

120

100

80

60

40

20

0

–20

PHASE

GAIN

OFFSET

NULL

1
2

3
4

5

6

7

8

AD745

TOP VIEW

NC

OUTPUT
OFFSET

NULL

– IN

+IN

+V

S

–V

S

NC = NO CONNECT

1

2
3
4
5

6

7

89

10

11

12

13

14

16

15

AD745

TOP VIEW

NC

NC

NC

NC NC

NC

NC
NC

NC

OFFSET

NULL

– IN

+IN OUTPUT

OFFSET
NULL

–V

S

+V

S

a

FEATURES
ULTRALOW NOISE PERFORMANCE

2.9 nV/ÏHz at 10 kHz

0.38 mV p-p, 0.1 Hz to 10 Hz

6.9 fA/ÏHz Current Noise at 1 kHz
EXCELLENT AC PERFORMANCE

12.5 V/ms 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

PRODUCT DESCRIPTION

The AD745 is an ultralow noise, high speed, FET input
operational 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 amplifier for high speed applications demanding low noise
and high dc precision. Furthermore, the AD745 does not
exhibit an output phase reversal.

1000

100

R

SOURCE

R

SOURCE

OP37 &

RESISTOR

E

O

( — )

High Speed, BiFET Op Amp

AD745

CONNECTION DIAGRAMS

8-Pin Plastic Mini-DIP (N) &

8-Pin Cerdip (Q) Packages

The AD745’s guaranteed, tested maximum input voltage noise
of 4 nV/√

Hz at 10 kHz is unsurpassed for a FET-input mono­lithic op amp, as is its maximum 1.0 µV p-p noise in a 0.1 Hz to
10 Hz bandwidth. 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 five performance
grades. The AD745J and AD745K are rated over the
commercial temperature range of 0°C to +70°C. The AD745A
and AD745B are rated over the industrial temperature range of
–40°C to +85°C. The AD745S is rated over the military
temperature range of –55°C to +125°C and is available
processed to MIL-STD-883B, Rev. C.

The AD745 is available in 8-pin plastic mini-DIP, 8-pin cerdip,
16-pin SOIC, or in chip form.

16-Pin SOIC (R) Package

REV. C

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.

10

INPUT NOISE VOLTAGE – nV/ Hz

1

100

AD745 & RESISTOR

OR

OP37 & RESISTOR

RESISTOR NOISE ONLY

1k 10k 100k

SOURCE RESISTANCE – Ω

(– – –)

AD745 + RESISTOR

( )

1M 10M

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] Fax: [phone]

AD745–SPECIFICA TIONS

(@ +258C and 615 V dc, unless otherwise noted)

Model AD745J/A

Conditions Min Typ Max Units

INPUT OFFSET VOLTAGE

1

Initial Offset 0.25 1.0/0.8 mV
Initial Offset T
vs. Temp. T
vs. Supply (PSRR) 12 V to 18 V
vs. Supply (PSRR) T

INPUT BIAS CURRENT

3

MIN
MIN

MIN

to T
to T

to T

MAX
MAX

MAX

2

90 96 dB

2 µV/°C

88 dB

1.5 mV

Either Input VCM = 0 V 150 400 pA
Either Input

@ T

MAX

Either Input VCM = +10 V 250 600 pA

VCM = 0 V 8.8/25.6 nA

Either Input, VS = ±5 V VCM = 0 V 30 200 pA

INPUT OFFSET CURRENT VCM = 0 V 40 150 pA

Offset Current

@ T

MAX

VCM = 0 V 2.2/6.4 nA

FREQUENCY RESPONSE

Gain BW, Small Signal G = –4 20 MHz
Full Power Response VO = 20 V p-p 120 kHz
Slew Rate G = –4 12.5 V/µs
Settling Time to 0.01% 5 µs
Total Harmonic f = 1 kHz

Distortion

4

G = –4 0.0002 %

INPUT IMPEDANCE

Differential 1 × 1010i20 ΩipF
Common Mode 3 × 1011i18 ΩipF

INPUT VOLTAGE RANGE

Differential
Common-Mode Voltage +13.3, –10.7 V
Over Max Operating Range

5

6

–10 +12 V

±20 V

Common-Mode

Rejection Ratio VCM = ±10 V 80 95 dB

T

MIN

to T

MAX

78 dB

INPUT VOLTAGE NOISE 0.1 to 10 Hz 0.38 µV p-p

f = 10 Hz 5.5 nV/√Hz
f = 100 Hz 3.6 nV/√Hz
f = 1 kHz 3.2 5.0 nV/√Hz

f = 10 kHz 2.9 4.0 nV/√Hz
INPUT CURRENT NOISE f = 1 kHz 6.9 fA/√Hz
OPEN LOOP GAIN VO = ±10 V

R

≥ 2 kΩ 1000 4000 V/mV

LOAD

T

to T

MIN

R

MAX

= 600 Ω 1200 V/mV

LOAD

800 V/mV

OUTPUT CHARACTERISTICS

Voltage R

Current Short Circuit 20 40 mA

≥ 600 Ω +13, –12 V

LOAD

R

≥ 600 Ω +13.6, –12.6 V

LOAD

T

to T

MIN

R

MAX

≥ 2 kΩ±12 +13.8, –13.1 V

LOAD

+12, –10 V

POWER SUPPLY

Rated Performance ±15 V
Operating Range ±4.8 ±18 V
Quiescent Current 8 10.0 mA

TRANSISTOR COUNT # of Transistors 50

NOTES

1

Input offset voltage specifications are guaranteed after 5 minutes of operations at TA = +25°C.

2

Test conditions: +VS = 15 V, –VS = 12 V to 18 V and +VS = 12 V to +18 V, –VS = 15 V.

3

Bias current specifications are guaranteed maximum at either input after 5 minutes of operation at TA = +25°C. For higher temperature, the current doubles every 10°C.

4

Gain = –4, RL = 2 kΩ, CL = 10 pF.

5

Defined as voltagc 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. C

AD745

ABSOLUTE MAXIMUM RATINGS

Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±18 V

Internal Power Dissipation

2

1

Plastic Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 W

Cerdip Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 W

SOIC Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 W

Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±V

S

Output Short-Circuit Duration . . . . . . . . . . . . . . . . Indefinite

Differential Input Voltage . . . . . . . . . . . . . . . . . . +V

and –V

S

S

Storage Temperature Range (Q) . . . . . . . . . –65°C to +150°C

Storage Temperature Range (N, R) . . . . . . . –65°C to +125°C

Operating Temperature Range

AD745J/K . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to +70°C

AD745A/B . . . . . . . . . . . . . . . . . . . . . . . . . –40°C to +85°C

AD745S . . . . . . . . . . . . . . . . . . . . . . . . . . –55°C to +125°C

Lead Temperature Range (Soldering 60 sec) . . . . . . . . +300°C

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: θJA = 100°C/W, θJC = 50°C/W
8-Pin Cerdip Package: θ
8-Pin Plastic SOIC Package: θJA = 100°C/W, θJC = 30°C/W

= 110°C/W, θJC = 30°C/W

JA

METALIZATION PHOTOGRAPH

Dimensions shown in inches and (mm).

ESD SUSCEPTIBILITY

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 1000 volts, while all other pins will
pass at voltages exceeding 2500 volts.

ORDERING GUIDE

Package

Model Temperature Range Option*

AD745JN 0°C to +70°C N-8
AD745AN –40°C to +85°C N-8
AD745JR-16 0°C to +70°C R-16

*N = Plastic DIP; R = Small Outline IC.

REV. C

–3–

AD745

10

100

1k

10k

LOAD RESISTANCE – Ω

5

10

15

20

25

30

35

0

OUTPUT VOLTAGE SWING – Volts p-p

200
100

10

1

0.1

0.01
10k 100k 1M 10M 100M

FREQUENCY – Hz

OUTPUT IMPEDANCE – Ω

CLOSED-LOOP GAIN = –5

28

26

24

22

20

18

16

14

–60 –40 –20020

40 60 80 100 120 140

GAIN BANDWIDTH PRODUCT – MHz

TEMPERATURE – C

–Typical Characteristics

(@ + 258C, VS = 615 V unless otherwise noted)

20

R = 10kΩ

LOAD

15

10

5

INPUT VOLTAGE SWING – Volts

0

0

5

SUPPLY VOLTAGE VOLTS

+V

IN

–V

IN

10 15 20

+

–

Figure 1. Input Voltage Swing vs.
Supply Voltage

12

9

6

3

QUIESCENT CURRENT – mA

20

R = 10kΩ

LOAD

15

10

5

OUTPUT VOLTAGE SWING – Volts

0

0

POSITIVE

SUPPLY

NEGATIVE

SUPPLY

5101520

SUPPLY VOLTAGE VOLTS

+

–

Figure 2. Output Voltage Swing vs.
Supply Voltage

–6

10

–7

10

–8

10

–9

10

–10

10

–11

INPUT BIAS CURRENT – Amps

10

Figure 3. Output Voltage Swing vs.
Load Resistance

–12

0

0

510

SUPPLY VOLTAGE ± VOLTS

15 20

Figure 4. Quiescent Current vs.
Supply Voltage

300

200

100

INPUT BIAS CURRENT – pA

0

–9 –6 –3 3 6 9
COMMON-MODE VOLTAGE – Volts

Figure 7. Input Bias Current vs.
Common-Mode Voltage

0–12

12

10

–60 –40 –20020 40 60

TEMPERATURE – °C

80 100 120 140

Figure 5. Input Bias Current vs.
Temperature

80

70

60

50

40

30

CURRENT LIMIT – mA

20

10

0
– 60 – 40

+ OUTPUT
CURRENT

– OUTPUT
CURRENT

0 20 40 60 80 100 120 140

– 20

TEMPERATURE – °C

Figure 8. Short Circuit Current Limit
vs. Temperature

Figure 6. Output Impedance vs.
Frequency

Figure 9. Gain Bandwidth Product
vs. Temperature

–4–

REV. C