ANALOG DEVICES OP285 Service Manual

Dual 9 MHz Precision

8

7

6

5

V+

–IN B

+IN B

OUT B

1

2

3

4

–IN A

+IN A

V–

OUT A

+–

+–

OP285

www.BDTIC.com/ADI

a

FEATURES
Low Offset Voltage: 250 V
Low Noise: 6 nV/√ Hz
Low Distortion: 0.0006%
High Slew Rate: 22 V/s
Wide Bandwidth: 9 MHz
Low Supply Current: 5 mA
Low Offset Current: 2 nA
Unity-Gain Stable
SO-8 Package

APPLICATIONS
High Performance Audio
Active Filters
Fast Amplifiers
Integrators

GENERAL DESCRIPTION

The OP285 is a precision high-speed amplifier featuring the
Butler Amplifier front-end. This new front-end design com­bines the accuracy and low noise performance of bipolar
transistors with the speed of JFETs. This yields an amplifier
with high slew rates, low offset and good noise performance
at low supply currents. Bias currents are also low compared
to bipolar designs.

The OP285 offers the slew rate and low power of a JFET
amplifier combined with the precision, low noise and low
drift of a bipolar amplifier. Input offset voltage is laser-trimmed
and guaranteed less than 250 µV. This makes the OP285 useful
in dc-coupled or summing applications without the need for
special selections or the added noise of additional offset
adjustment circuitry. Slew rates of 22 V/µs and a bandwidth
of 9 MHz make the OP285 one of the most accurate medium
speed amplifiers available.

Operational Amplifier

OP285

PIN CONNECTIONS

8-Lead Narrow-Body SO (S-Suffix)

OUT A

1

–IN A

2

OP285

3

4

TOP VIEW

(Not to Scale)

+IN A

V–

8-Lead Epoxy DIP (P-Suffix)

The combination of low noise, speed and accuracy can be used
to build high speed instrumentation systems. Circuits such as
instrumentation amplifiers, ramp generators, bi-quad filters and
dc-coupled audio systems are all practical with the OP285. For
applications that require long term stability, the OP285 has a
guaranteed maximum long term drift specification.

The OP285 is specified over the XIND—extended industrial—
(–40°C to +85°C) temperature range. OP285s are available in
8-pin plastic DIP and SOIC-8 surface mount packages.

8

7

6

5

V+

OUT B

–IN B

+IN B

*

*Patents pending

REV. A

Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its

may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.

use, nor for any infringements of patents or other rights of third parties that

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] © Analog Devices, Inc., 2001

OP285–SPECIFICATIONS

www.BDTIC.com/ADI

(@ Vs = 15.0 V, TA = 25C, unless otherwise noted.)

Parameter Symbol Conditions Min Typ Max Unit

INPUT CHARACTERISTICS

Offset Voltage V

Input Bias Current I

Input Offset Current I

Input Voltage Range V

OS

V

OS

B

I

B

OS

I

OS

CM

Common-Mode Rejection CMRR V

Large-Signal Voltage Gain A

VO

A

VO

A

VO

–40°C ≤ TA ≤ +85°C 600 µV
VCM = 0 V 100 350 nA
VCM = 0 V, –40°C ≤ TA ≤ +85°C 400 nA
VCM = 0 V 2 ±50 nA
VCM = 0 V, –40°C ≤ TA ≤ +85°C2±100 nA

–10.5 10.5 V

= ±10.5 V,

CM

–40°C ≤ T

≤ +85°C 80 106 dB

A

RL = 2 kΩ 250 V/mV
RL = 2 kΩ, –40°C ≤ TA ≤ +85°C 175 V/mV
RL = 600 Ω 200 V/mV

35 250 µV

Common-Mode Input Capacitance 7.5 pF
Differential Input Capacitance 3.7 pF
Long-Term Offset Voltage ∆V
Offset Voltage Drift ∆V

OS

/∆T1µV/°C

OS

Note 1 300 µV

OUTPUT CHARACTERISTICS

Output Voltage Swing V

O

V

O

RL = 2 kΩ –13.5 +13.9 +13.5 V
RL = 2 kΩ, –40°C ≤ TA ≤ +85°C –13 +13.9 +13 V
RL = 600 Ω, V

= ±18 V –16/+14 V

S

POWER SUPPLY

Power Supply Rejection Ratio PSRR V

PSRR V

Supply Current I

SY

I

SY

= ±4.5 V to ±18 V 85 111 dB

S

= ±4.5 V to ±18 V,

S

–40°C ≤ T

≤ +85°C80 dB

A

VS = ±4.5 V to ±18 V, VO = 0 V,
R

= x, –40°C ≤ TA ≤ +85°C45mA

L

VS = ±22 V, VO, = 0 V, RL = x
–40°C ≤ T

≤ +85°C 5.5 mA

A

Supply Voltage Range VS ±4.5 ± 22 V

DYNAMIC PERFORMANCE

Slew Rate SR R

= 2 kΩ 15 22 V/µs

L

Gain Bandwidth Product GBP 9 MHz
Phase Margin ␪o 62 Degrees
Settling Time t

s

t

s

Distortion A

Voltage Noise Density e

Current Noise Density i

n

e

n

n

To 0.1%, 10 V Step 625 ns
To 0.01%, 10 V Step 750 ns

= 1, V

V

f = 1 kHz, R

= 8.5 V p-p,

OUT

= 2 kΩ –104 dB

L

f = 30 Hz 7 nV/√Hz
f = 1 kHz 6 nV/√Hz
f = 1 kHz 0.9 pA/√Hz

Headroom THD + Noise ≤ 0.01%,

RL = 2 kΩ, VS = ±18 V >12.9 dBu

NOTE

1

Long-term offset voltage is guaranteed by a 1,000 hour life test performed on three independent wafer lots at 125 °C, with an LTPD of 1.3.

Specifications subject to change without notice.

–2–

REV. A

OP285

www.BDTIC.com/ADI

ABSOLUTE MAXIMUM RATINGS

Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±22 V

Input Voltage
Differential Input Voltage

2

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±18 V

2

. . . . . . . . . . . . . . . . . . . . . . ±7.5 V

Output Short-Circuit Duration to Gnd
Storage Temperature Range

P, S Package . . . . . . . . . . . . . . . . . . . . . . . –65°C to +150°C

Operating Temperature Range

OP285G . . . . . . . . . . . . . . . . . . . . . . . . . . . –40°C to +85°C

Junction Temperature Range

P, S Package . . . . . . . . . . . . . . . . . . . . . . . –65°C to +150°C

1

3

. . . . . . . . . Indefinite

Package Type 

8-Pin Plastic DIP (P) 103 43 °C/W
8-Pin SOIC (S) 158 43 °C/W

NOTES

1

Absolute Maximum Ratings apply to packaged parts, unless otherwise noted.

2

For supply voltages less than ± 7.5 V, the absolute maximum input voltage is
equal to the supply voltage.

3

Shorts to either supply may destroy the device. See data sheet for full details.

4

␪JA is specified for the worst case conditions, i.e., ␪JA is specified for device in

socket for cerdip, P-DIP, and LCC packages; ␪JA is specified for device soldered
in circuit board for SOIC package.

Lead Temperature Range (Soldering 60 Sec) . . . . . . . . 300°C

ORDERING GUIDE

Temperature Package Package

Model Range Description Option

OP285GP* –40°C to +85°C 8-Pin Plastic DIP N-8
OP285GS –40°C to +85°C 8-Pin SOIC S0-8
OP285GSR –40°C to +85°C S0-8 Reel, 2500 pcs.

*Not for new designs. Obsolete April 2002.

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 OP285 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.

4

JA

WARNING!



JC

ESD SENSITIVE DEVICE

Unit

REV. A

–3–

OP285

www.BDTIC.com/ADI

25

T

= 25C

A

20

R

= 2k

L

15

10

5

0

–5

–10

–15

OUTPUT VOLTAGE SWING – V

–20

–25

0 5 10 15 20 25

SUPPLY VOLTAGE – V

+VOM

–VOM

TPC 1. Output Voltage Swing vs.
Supply Voltage

50

VS = 15V

VS = 15V
R

= 2k

R

= 2k

L

L

45

40

35

30

SLEW RATE – V/s

25

20

TEMPERATURE – C

–SR

+SR

0

100–25–50 755025

TPC 4. Slew Rate vs. Temperature

1500

VS = 15V
V

= 10V

O

1250

1000

750

500

OPEN-LOOP GAIN – V/MV

250

0
–50

R

+GAIN

= 600

L

–25

+GAIN

= 2k

R

L

–GAIN

= 2k

R

L

–GAIN

= 600

R

L

0

TEMPERATURE – C

755025

TPC 2. Open-Loop Gain
vs. Temperature

CLOSED-LOOP GAIN – dB

–10

–20

–30

50

40

30

20

10

0

= +100

A

VCL

= +10

A

VCL

A

= +1

VCL

1k

10k 100k 1M 10M 100M

FREQUENCY – Hz

VS = 15V

= +25C

T

A

TPC 5. Closed-Loop Gain
vs. Frequency

100

30

VS = 15V
R

= 2k

L

25

20

15

+SR

–SR

10

SLEW RATE – V/s

5

0

0

DIFFERENTIAL INPUT VOLTAGE – V

1.0

0.80.60.40.2

TPC 3. Slew Rate vs. Differential
Input Voltage

60

50

40

A

= +10

30

A

VCL

20

IMPEDANCE – 

10

0
100

1k 10k 100k 1M 10M

VCL

= +100

FREQUENCY – Hz

VS = 15V

= 25C

T

A

A

= +1

VCL

TPC 6. Closed-Loop Output Imped
ance vs. Frequency

120

= 15V

V

S

= 25C

T

A

COMMON MODE REJECTION – dB

100

80

60

40

20

0

100

1k 10k 100k 1M 10M

FREQUENCY – Hz

TPC 7. Common-Mode Rejection
vs. Frequency

120

100

VS = 15V

80

= 25C

T

A

60

40

20

POWER SUPPLY REJECTION – dB

0

10

100 1k 10k 100k 1M

FREQUENCY – Hz

TPC 8. Power Supply Rejection
vs. Frequency

–4–

–PSRR

+PSRR

100

80

60

– dB

40

MIN

PHASE

20

0

OPEN-LOOP G

–20

–40

–60

1k

GAIN

10k 100k 1M 10M 100M

FREQUENCY – Hz

V

= 15V

S

= 2k

R

L

T

= 25C

A

0

= 58

N

TPC 9. Open-Loop Gain, Phase
vs. Frequency

REV. A

0

45

90

135

180

225

270

PHASE – Degrees

Typical Performance Characteristics–OP285

www.BDTIC.com/ADI

11

10

9

8

GAIN BANDWIDTH PRODUCT – MHz

7

–25 755025

–50 100

TEMPERATURE – C

GBW

0

ø

M

65

60

55

50

40

TPC 10. Gain Bandwidth Product,
Phase Margin vs. Temperature

30

25

20

15

10

TA = 25C

= 15V

V

S

= +1

A

VCL

5

MAXIMUM OUTPUT SWING – V

R

= 2k

L

0

1k

10k 10M1M100k

FREQUENCY – Hz

TPC 13. Maximum Output Swing
vs. Frequency

100

PHASE MARGIN – Degrees

90

80

70

60

50

40

OVERSHOOT – %

30

20

10

0

0

A = +1

VCL

NEGATIVE EDGE

A = +1

VCL

POSITIVE EDGE

VS = 15V

= 2k

R

L

= 100mV p-p

V

IN

100

LOAD CAPACITANCE – pF

300

TPC 11. Small-Signal Overshoot vs.|
Load Capacitance

5.0

4.5

TA = +85C

4.0

TA = +25C

TA = –40C

3.5

SUPPLY CURRENT – mA

3.0
0

5

SUPPLY VOLTAGE – V

TPC 14. Supply Current vs.
Supply Voltage

16

14

–VOM

12

10

8

6

4

2

MAXIMUM OUTPUT SWING – Volts

0

500

400200

100 1k 10k

+VOM

TA = 25C

= 15V

V

S

LOAD RESISTANCE – 

TPC 12. Maximum Output Voltage
vs. Load Resistance

120

110

100

90

SINK

80

70

60

50

40

SOURCE

30

ABSOLUTE OUTPUT CURRENT – mA

20

1510

25

–50

0

–25

TEMPERATURE – C

VS = 15V

7525 50

100

TPC 15. Short Circuit Current vs.
Temperature

300

VS = 15V

250

200

150

100

INPUT BIAS CURRENT – nA

50

0

–25

–50

0

TEMPERATURE – C

755025

TPC 16. Input Bias Current vs.
Temperature

100

5

Hz

4

3

2

1

CURRENT NOISE DENSITY – pA/

10

100 100k1k

FREQUENCY – Hz

TPC 17. Current Noise Density vs.
Frequency

REV. A

–5–

VS = 15V
T

= 25C

A

250

–40C TA +85C

TC V

402 OP AMPS

– V/ C

OS

200

150

UNITS

100

50

0

0

1

TPC 18. tC VOS Distribution

10

98765432