Analog Devices AD795KN, AD795JN Datasheet

1
2
3
4

8
7
6
5

AD795

NC
–IN
+IN

–V

S

NC
+V

S

OUTPUT
NC

NC = NO CONNECT

Low Power, Low Noise

50

0

5–4

10

–5

30

20

40

43210–1–2–3

INPUT OFFSET VOLTAGE DRIFT – µV/°C

PERCENTAGE OF UNITS

SAMPLE SIZE = 570

a

FEATURES
Low Power Replacement for Burr-Brown
OPA-111, OPA-121 Op Amps
Low Noise

2.5 mV p-p max, 0.1 Hz to 10 Hz
11 nV/√

0.6 fA/√

High DC Accuracy

250 mV max Offset Voltage
3 mV/8C max Drift
1 pA max Input Bias Current
Low Power: 1.5 mA max Supply Current

Available in Low Cost Plastic Mini-DIP and Surface

Mount (SOIC) Packages

APPLICATIONS
Low Noise Photodiode Preamps
CT Scanners
Precision l-to-V Converters

PRODUCT DESCRIPTION

The AD795 is a low noise, precision, FET input operational
amplifier. It offers both the low voltage noise and low offset drift
of a bipolar input op amp and the very low bias current of a
FET-input device. The 10
insures that input bias current is essentially independent of
common-mode voltage and supply voltage variations.

The AD795 has both excellent dc performance and a guaran­teed and tested maximum input voltage noise. It features 1 pA
maximum input bias current and 250 µV maximum offset volt-
age, along with low supply current of 1.5 mA max.

Hz max at 10 kHz
Hz at 1 kHz

1k

14

Ω common-mode impedance

Precision FET Op Amp

AD795

CONNECTION DIAGRAMS

8-Pin Plastic Mini-DIP (N) Package

30

Vs = ±15V

25

20

15

10

5

OUTPUT VOLTAGE SWING – Volts p-p

0

10

100 1k

LOAD RESISTANCE –

Ω

8-Pin SOIC (R) Package

Furthermore, the AD795 features a guaranteed low input noise
of 2.5 µV p-p (0.1 Hz to 10 Hz) and a 11 nV/√
level at 10 kHz. The AD795 has a fully specified and tested
input offset voltage drift of only 3 µV/°C max.

The AD795 is useful for many high input impedance, low noise
applications. The AD795J and AD795K are rated over the
commercial temperature range of 0°C to +70°C.

The AD795 is available in 8-pin plastic mini-DIP and 8-pin
surface mount (SOIC) packages.

10k

Hz max noise

REV. A

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.

100

10

VOLTAGE NOISE SPECTRAL DENSITY – nV/√Hz

1

10 100 10k1k

FREQUENCY – Hz

AD795 Voltage Noise Spectral Density

Typical Distribution of Average Input Offset Voltage Drift

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

AD795–SPECIFICA TIONS

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

AD795JN/JR AD795K

Parameter Conditions Min Typ Max Min Typ Max Units

INPUT OFFSET VOLTAGE

1

Initial Offset 100 500 50 250 µV

Offset T

MIN–TMAX

300 1000 100 400 µV
vs. Temperature 3 10 1 3 µV/°C
vs. Supply (PSRR) 86 110 90 110 dB
vs. Supply (PSRR) T

INPUT BIAS CURRENT

2

MIN–TMAX

84 100 87 100 dB

Either Input VCM = 0 V 1 2/3 1 1 pA
Either Input @ T

=V

MAX

Either Input V
Offset Current V
Offset Current @ T

=V

MAX

OPEN-LOOP GAIN V

= 0 V 23 23 pA

CM

= +10 V 1 1 pA

CM

= 0 V 0.1 1.0 0.1 0.6 pA

CM

= 0 V 2 2 pA

CM

= ±10 V

O

≥ 10 kΩ 110 120 110 120 dB

R

LOAD

R

≥ 10 kΩ 100 108 100 108 dB

LOAD

INPUT VOLTAGE NOISE 0.1 Hz to 10 Hz 1.0 3.3 1.0 2.5 µV p-p

f = 10 Hz 20 50 20 40 nV/√Hz
f = 100 Hz 12 40 12 30 nV/√
f = 1 kHz 11 17 11 15 nV/√

Hz
Hz

f = 10 kHz 9 11 9 11 nV/√Hz

INPUT CURRENT NOISE f = 0.1 Hz to 10 Hz 13 13 fA p-p

f = 1 kHz 0.6 0.6 fA/√Hz

FREQUENCY RESPONSE

Unity Gain, Small Signal G = –1 1.6 1.6 MHz
Full Power Response V

Slow Rate, Unity Gain V

SETTLING TIME

3

= 20 V p-p

O

R

= 2 kΩ 16 16 kHz

LOAD

= 20 V p-p

OUT

R

= 2 kΩ 11V/µs

LOAD

To 0.1% 10 V Step 10 10 µs
To 0.01% 10 V Step 11 11 µs
Overload Recovery

4

50% Overdrive 2 2 µs

Total Harmonic f = 1 kHz

Distortion R1 ≥ 10 kΩ

VO = 3 V rms –108 –108 dB

INPUT IMPEDANCE

Differential V

= ±1 V 1012i210

DIFF

12

i2 ΩipF

Common Mode 1014i2.2 1014i2.2 ΩipF

INPUT VOLTAGE RANGE

Differential

5

±20 ±20 V
Common-Mode Voltage ±10 ±11 ±10 ±11 V
Over Max Operating Temperature ±10 ±10 V
Common-Mode Rejection Ratio V

= ±10 V 90 110 94 110 dB

CM

T

MIN–TMAX

86 100 90 100 dB

OUTPUT CHARACTERISTICS

Voltage R
Current V

≥ 2 kΩ VS –4 VS –2.5 VS –4 VS –2.5 V

LOAD

T

MIN–TMAX

= ±10 V ± 5 ±10 ±5 ±10 mA

OUT

VS –4 VS –4 V

Short Circuit ±15 ±15 mA

POWER SUPPLY

Rated Performance ±15 ±15 V
Operating Range ±4 ±18 ±4 ±18 V
Quiescent Current 1.3 1.5 1.3 1.5 mA

–2–

REV. A

AD795

NOTES

1

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

2

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.

3

Gain = –1, R1 = 10 kΩ.

4

Defined as the time required for the amplifier’s output to return to normal operation after removal of a 50% overload from the amplifier input.

5

Defined as the maximum continuous voltage between the inputs such that neither input exceeds ±10 V from ground.

All min and max specifications are guaranteed.
Specifications subject to change without notice.

ABSOLUTE MAXIMUM RATINGS

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

Internal Power Dissipation

2

(@ TA = +25°C)

1

SOIC Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500 mW

8-Pin Mini-DIP Package . . . . . . . . . . . . . . . . . . . . 750 mW

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

S

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

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

and –V

S

S

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

Operating Temperature Range

AD795J/K . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to +70°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 Mini-DIP Package: θJA = 100°C/Watt
8-Pin Small Outline Package: θJA = 155°C/Watt

ESD SUSCEPTIBILITY

ESD (electrostatic discharge) sensitive device. Electrostatic
charges as high as 4000 volts, which readily accumulate on the
human body and on test equipment, can discharge without
detection. Although the AD795 features proprietary ESD pro­tection circuitry, permanent damage may still occur on these
devices if they are subjected to high energy electrostatic dis­charges. Therefore, proper ESD precautions are recommended
to avoid any performance degradation or loss of functionality.

ORDERING GUIDE

Model Temperature Range Package Option*

AD795JN 0°C to +70°C N-8
AD795KN 0°C to +70°C N-8
AD795JR 0°C to +70°C R-8

*N = Plastic mini-DIP; R = SOIC package.

REV. A

–3–

AD795–Typical Characteristics

OUTPUT VOLTAGE RANGE – ±Volts

SUPPLY VOLTAGE – ±Volts

20

0

020

15

5

5

10

10

15

R

L

= 10k

+V

OUT

–V

OUT

Ω

10

–9

10

–14

140

10

–11

10

–13

–40

10

–12

–60

10

–10

120100806040200–20

INPUT BIAS CURRENT – Amps

TEMPERATURE – °C

20

Ω

= 10k

R

L

15

+V

IN

10

–V

IN

5

INPUT COMMON MODE RANGE – ±Volts

0

020

5

10

15

SUPPLY VOLTAGE – ±Volts

Figure 1. Common-Mode Voltage Range vs. Supply

30

Vs = ±15V

25

20

15

10

5

OUTPUT VOLTAGE SWING – Volts p-p

Figure 2. Output Voltage Range vs. Supply Voltage

1.0

0.95

0.90

0.85

0.80

0.75

0.70

INPUT BIAS CURRENT – pA

0.65

0

10

100 1k

LOAD RESISTANCE –

Ω

10k

0.60

Figure 3. Output Voltage Swing vs. Load Resistance

50

SAMPLE SIZE = 1058

40

30

20

PERCENTAGE OF UNITS

10

0

0

INPUT BIAS CURRENT – pA

1.51.5

Figure 5. Typical Distribution of Input Bias Current

2

Figure 6. Input Bias Current vs. Temperature

0

5

SUPPLY VOLTAGE – ±Volts

1510

Figure 4. Input Bias Current vs. Supply

20

REV. A–4–

VOLTAGE NOISE – µV p-p

SOURCE RESISTANCE – Ω

1k

10

1.0
10

3

10

4

10

9

10

8

10

7

10

6

10

5

Noise Bandwidth: 0.1 to 10Hz

100

FREQUENCY – Hz

1k

10

1.0

100

1 10 10M1M100k10k1k100

VOLTAGE NOISE (REFERRED TO INPUT) – nV/√Hz

1.00

0.95

0.90

0.85

0.80

0.75

0.70

INPUT BIAS CURRENT – pA

0.65

0.60
–10–15

–5

COMMON MODE VOLTAGE – Volts

0

+10+5

+15

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

AD795

–4

10

–5

10

–I

IN

–6

10

–7

10

–8

10

–9

10

–10

10

–11

10

INPUT BIAS CURRENT – Amperes

–12

10

–13

10

–14

10

–5

–6

–4 –3

–2 –1

0

12

DIFFERENTIAL INPUT VOLTAGE – ±Volts

Figure 8. Input Bias Current vs. Differential Input Voltage

4

+I

IN

563

140

100

10

1.0

0.1

0.01

CURRENT NOISE – fA/√Hz

15

f = 1kHz

12.5

10

VOLTAGE NOISE – nV/√Hz

7.5

5

–60

–40

VOLTAGE NOISE

–20

CURRENT NOISE

100 120806040200

TEMPERATURE – °C

Figure 9. Voltage and Current Noise Spectral Density vs.
Temperature

50

SAMPLE SIZE = 344

40

f = 0.1 TO 10Hz

Figure 10. Input Voltage Noise vs. Source Resistance

30

20

PERCENTAGE OF UNITS

10

0

0

0.1 TO 10Hz INPUT VOLTAGE NOISE p-p – µV

21

Figure 11. Typical Distribution of Input Voltage Noise

REV. A

3

Figure 12. Input Voltage Noise Spectral Density

–5–