Analog Devices AD8676 Service Manual

Ultra Precision, 36 V, 2.8 nV/√Hz

p

FEATURES

Very low voltage noise 2.8 nV/√Hz @ 1 kHz Rail-to-rail output swing Low input bias current: 2 nA maximum Very low offset voltage: 12 μV typical Low input offset drift: 0.6 μV/°C maximum Very high gain: 120 dB Wide bandwidth: 10 MHz typical ±5 V to ±18 V operation

APPLICATIONS

Precision instrumentation PLL filters Laser diode control loops Strain gage amplifiers Medical instrumentation Thermocouple amplifiers

GENERAL DESCRIPTION

The AD8676 precision operational amplifier offers ultralow offset, drift, and voltage noise combined with very low input bias currents over the full operating temperature range. The AD8676 is a precision, wide bandwidth op amp featuring rail-torail output swings and very low noise. Operation is fully specified from ±5 V to ±15 V.

The AD8676 features a rail-to-rail output like that of the OP184, but with wide bandwidth and even lower voltage noise, combined with the precision and low power consumption like that of the industry-standard OP07 amplifier. Unlike other low noise, rail-to-rail op amps, the AD8676 has very low input bias current and low input current noise.

With typical offset voltage of only 12 µV, offset drift of 0.2 µV/°C, and noise of only 0.10 V p-p (0.1 Hz to 10 Hz), the AD8676 is perfectly suited for applications where large error sources cannot be tolerated. Precision instrumentation, PLL and other precision filter circuits, position and pressure sensors, medical

Dual Rail-to-Rail Out

ut Op Am

AD8676

PIN CONFIGURATIONS

OUT A

1

AD8676

2

–IN A

+IN A

3

TOP VIEW

(Not to Scale)

V–

4

Figure 1. 8-Lead SOIC_N (R-8)

1

OUT A

2

–IN A

+IN A

AD8676

3

TOP VIEW

(Not to Scale)

4

V–

Figure 2. 8-Lead MSOP (RM-8)

instrumentation, and strain gage amplifiers benefit greatly from the very low noise, low input bias current, and wide bandwidth. Many systems can take advantage of the low noise, dc precision, and rail-to-rail output swing provided by the AD8676 to maximize SNR and dynamic range.

The smaller packages and low power consumption afforded by the AD8676 allow maximum channel density or minimum board size for space-critical equipment.

The AD8676 is specified for the extended industrial temperature range (−40°C to +125°C). The AD8676 is available in the 8-lead MSOP, and the popular 8-lead, narrow SOIC; both of which are lead-free packages. MSOP packaged devices are only available in tape and reel format.

For the single version of this ultraprecision rail-to-rail op amp, see the AD8675 data sheet.

8

7

6

5

8

7

6

5

V+

OUT B

–IN B

+IN B

V+

OUT B

–IN B

+IN B

06487-001

06487-002

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners.

AD8676

REVISION HISTORY

10/06—Revision 0: Initial Version

Thermal Resistance .......................................................................5

Power Sequencing .........................................................................5

ESD Caution...................................................................................5

Typical Perf or m an c e Charac t e r istics ..............................................6

Outline Dimensions ....................................................................... 10

Ordering Guide .......................................................................... 10

Rev. 0 | Page 2 of 12

AD8676

SPECIFICATIONS

ELECTRICAL SPECIFICATIONS

VS = ±5.0 V, VCM = 0 V, VO = 0 V, TA = +25°C, unless otherwise specified.

Table 1.

Parameter Symbol Conditions Min Typ Max Unit

INPUT CHARACTERISTICS

Offset Voltage V

OS

B Grade (SOIC) 12 50 μV B Grade (MSOP) 60 μV A Grade (SOIC, MSOP) 100 μV

Offset Voltage V

OS

B Grade (SOIC, MSOP) 15 160 μV A Grade (SOIC, MSOP) 250 μV

Input Bias Current I

B

−40°C ≤ TA ≤ +125°C −5.5 +1 +5.5 nA Input Offset Current I

OS

−40°C ≤ TA ≤ +125°C −2.8 +0.1 +2.8 nA Input Voltage Range −3.5 +3.5 V Common-Mode Rejection Ratio CMRR VCM = −3.0 V to +3.0 V 105 130 dB

−40°C ≤ TA ≤ +125°C 105 130 dB Open-Loop Gain A

VO

V

−40°C ≤ TA ≤ +125°C 700 1250 V/mV Offset Voltage Drift ΔVOS/ΔT −40°C ≤ TA ≤ +125°C 0.2 0.6 μV/°C

OUTPUT CHARACTERISTICS

Output Voltage High V

OH

−40°C ≤ TA ≤ +125°C +4.78 +4.82 V

Output Voltage Low V

OL

−40°C ≤ TA ≤ +125°C −4.93 −4.82 V

Short-Circuit Limit I Output Current I

SC

O

POWER SUPPLY

Power Supply Rejection Ratio PSRR VS = ±5.0 V to ±15.0 V 106 120 dB

−40°C ≤ TA ≤ +125°C 106 120 dB Supply Current/Amplifier I

SY

−40°C ≤ TA ≤ +125°C 2.7 3.4 mA DYNAMIC PERFORMANCE

Slew Rate SR RL = 2 kΩ 2.5 V/μs Gain Bandwidth Product GBP 10 MHz

NOISE PERFORMANCE

Voltage Noise e Voltage Noise Density e Current Noise Density i

n p-p

n

−40°C ≤ TA ≤ +125°C

−2 +0.5 +2 nA

−1 +0.1 +1 nA

RL = 2 kΩ to ground, 1000 2000 V/mV

= −3.5 V to +3.5 V

O

RL = 2 kΩ to ground +4.84 +4.86 V

RL = 2 kΩ to ground −4.95 −4.86 V

+40 mA ±20 mA

VO = 0 V 2.3 2.7 mA

0.1 Hz to 10 Hz 0.1 μV p-p f = 1 kHz 2.8 nV/√Hz f = 10 Hz 0.3 pA/√Hz

Rev. 0 | Page 3 of 12

AD8676

VS = ±15 V, VCM = 0 V, VO = 0 V, TA = +25°C, unless otherwise specified.

Table 2.

Parameter Symbol Conditions Min Typ Max Unit

INPUT CHARACTERISTICS

Offset Voltage V

OS

B Grade (SOIC) 12 50 μV B Grade (MSOP) 60 μV A Grade (SOIC, MSOP) 100 μV

Offset Voltage V

OS

B Grade (SOIC, MSOP) 15 160 μV A Grade (SOIC, MSOP) 250 μV

Input Bias Current I

B

−40°C ≤ TA ≤ +125°C −4.5 −1 +4.5 nA Input Offset Current I

OS

−40°C ≤ TA ≤ +125°C −2.8 −0.1 +2.8 nA Input Voltage Range −13.5 +13.5 V Common-Mode Rejection Ratio CMRR VCM = −12.5 V to +12.5 V 111 130 dB

−40°C ≤ TA ≤ +125°C 107 130 dB Open-Loop Gain A

VO

V

−40°C ≤ TA ≤ +125°C 700 1700 V/mV Offset Voltage Drift ΔVOS/ΔT −40°C ≤ TA ≤ +125°C 0.2 0.6 μV/°C

OUTPUT CHARACTERISTICS

Output Voltage High V

OH

−40°C ≤ TA ≤ +125°C +14.49 +14.59 V Output Voltage Low V

OL

−40°C ≤ TA ≤ +125°C −14.83 −14.69 V

Short-Circuit Limit I Output Current I

SC

O

POWER SUPPLY

Power Supply Rejection Ratio PSRR VS = ±5.0 V to ±15.0 V 106 120 dB

−40°C ≤ TA ≤ +125°C 106 120 dB Supply Current/Amplifier I

SY

−40°C ≤ TA ≤ +125°C 2.9 3.8 mA

DYNAMIC PERFORMANCE

Slew Rate SR RL =10 kΩ 2.5 V/μs Gain Bandwidth Product GBP 10 MHz

NOISE PERFORMANCE

Voltage Noise e Voltage Noise Density e Current Noise Density i

n p-p

n

−40°C ≤ TA ≤ +125°C

−2 −0.5 +2 nA

−1 −0.1 +1 nA

RL = 2 kΩ to ground, 1500 4000 V/mV

= −13.5 V to +13.5 V

O

RL = 2 kΩ to ground +14.65 +14.7 V

RL = 2 kΩ to ground −14.88 −14.75 V

+40 mA ±20 mA

VO = 0 V 2.5 2.9 mA

0.1 Hz to 10 Hz 0.1 μV p-p f = 1 kHz 2.8 nV/√Hz f = 10 Hz 0.3 pA/√Hz

Rev. 0 | Page 4 of 12

AD8676

ABSOLUTE MAXIMUM RATINGS

Table 3.

Parameter Rating

Supply Voltage ±18 V Input Voltage ±V Supply − 1.5 V Differential Input Voltage ±0.7 V Output Short-Circuit Duration to GND Indefinite Storage Temperature Range

RM, R Packages −65°C to +150°C Operating Temperature Range −40°C to +125°C Junction Temperature Range

RM, R Packages −65°C to +150°C Lead Temperature Range (Soldering, 10 sec) 300°C

THERMAL RESISTANCE

Table 4. Thermal Resistance

Package Type θ

8-Lead MSOP (RM) 210 45 °C/W 8-Lead SOIC_N (R) 158 43 °C/W

JA

θ

JC

Unit

POWER SEQUENCING

The op amp supplies must be established simultaneously with, or before, any input signals are applied.

If this is not possible, the input current must be limited to 10 mA.

Stresses above those listed under Absolute Maximum Ratings may cause permanent 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.

ESD CAUTION

Rev. 0 | Page 5 of 12

AD8676

TYPICAL PERFORMANCE CHARACTERISTICS

±15 V and ±5 V, TA = 25°C, unless otherwise specified.

10

9

8

7

6

5

4

3

2

VOLTAGE NOISE DENSITY (nV/ Hz)

1

0

1 10 100 1k 10k

FREQUENCY (Hz)

Figure 3. Voltage Noise Density vs. Frequency

100k

06487-003

150

100

50

(µV)

0

OS

V

–50

–100

–150

–45 135

–30 –15 0 15 30 45 60 75 90 105 120

TEMPERATURE (° C)

Figure 6. Offset Voltage vs. Temperature

06487-006

90

80

70

60

50

40

30

NUMBER OF AMPLIFIERS

20

10

0

–100 –80 –60 –40 –20 0 20 40 60 80 100

V

(µV)

OS

Figure 4. Input Offset Voltage Distribution

25

20

15

10

NUMBER OF AMPL IFIERS

5

0

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

0.75

Figure 5. T

TCVOS (µV/°C)

Distribution

CVOS

TA = 25°C

0.80

0.85

120

100

80

60

40

NUMBER OF AMPLIFIERS

20

0

–0.65

–0.55 –0. 45 –0. 35 –0.25 –0.15 –0.05 0.05

06487-004

Figure 7. Input Bias Current, V

160

140

120

100

80

60

NUMBER OF AMPLIFIERS

40

20

0

–

0.65

–

1.00

0.90

0.95

06487-005

0.60–0.55–0.50–0.45–0.40–0.35–0.30–0.25–0.20–0.15

Figure 8. Input Bias Current, V

IB (nA)

= ±15 V

SY

= ±5 V

SY

06487-007

06487-008

Rev. 0 | Page 6 of 12

AD8676

= 35pF = 55.2

100M

180

120

60

0

–60

–120

–180

06487-013

PHASE MARGIN ( Degrees)

06487-012

5

4

3

2

1

0

(nA)

B

I

–1

–2

–3

–4

–5

–40 –20 0 20 40 60 80 100

VSY= ±5V

VSY= ±15V

TEMPERATURE (° C)

Figure 9. Input Bias Current vs. Temperature

3.0

2.5

2.0

1.5

1.0

SUPPLY CURRENT (mA)

0.5

0

5 1015202530

SUPPLY VOLTAGE (V)

Figure 10. Supply Current vs. Total Supply Voltage

120

100

GAIN (dB)

–20

–40

–60

–80

–100

–120

06487-009

GAIN

80

60

PHASE

40

20

0

100

10k1k 100k 10M1M

FREQUENCY (Hz)

RL = 2kΩ C

L

θ

M

Figure 12. Gain and Phase vs. Frequency

60

50

40

G = 100

30

20

G = 10

10

0

G = 1

–10

CLOSED-LOOP GAIN (dB)

–20

–30

–40

35

06487-010

1k 10k 100k

FREQUENCY (Hz)

1M 10M

Figure 13. Closed-Loop Gain vs. Frequency

3.5

3.0

2.5

2.0

1.5

1.0

SUPPLY CURRENT (mA)

0.5

0

–40 –20 0 20 40 60 80 100

VS= ±15V

VS= ±5V

TEMPERATURE (° C)

Figure 11. Supply Current vs. Temperature

120

06487-011

Rev. 0 | Page 7 of 12

70

60

50

40

(Ω)

OUT

Z

30

20

10

0

1k 10k 100k 1M 10M

AVO= 100

FREQUENCY (Hz)

Figure 14. Z

AVO= 10

vs. Frequency

OUT

AVO= 1

100M

06487-014

AD8676

15

10

5

VIN = ±10V R

= 2kΩ

L

A

= +1

V

–0.1

–0.2

0.1

50

V

0

IN

40

30

20

0

VOLTAGE (V)

–5

–10

–15

TIME (10µs/DIV)

Figure 15. Large Signal Transient Response, V

4

3

2

1

0

VOLTAGE (V)

–1

–2

–3

–4

TIME (10µs/DIV)

Figure 16. Large Signal Transient Response, V

= ±15 V

SY

VIN = ±3.5V R

= 2kΩ

L

A

= +1

V

= ±5 V

SY

–0.3

–0.4

INPUT VOLTAGE (V)

–0.5

–0.6

–0.7

–4 1 6 11 16 21 26 31

06487-015

V

OUT

TIME (µs)

VIN = 200mV p-p A

= –100

VO

R

= 10kΩ

L

10

0

OUTPUT VOLTAGE (V)

–10

–20

–30

36

06487-018

Figure 18. Positive Overvoltage Recovery

0.3

0.2

0.1

0

–0.1

–0.2

INPUT VOLTAGE (V)

–0.3

–0.4

–0.5

–4 1 6 11 16 21 26 31

06487-016

V

OUT

IN

TIME (µs)

VIN = 200mV p-p A

= –100

VO

R

= 10kΩ

L

50

40

30

20

10

0

OUTPUT VOLTAGE (V)

–10

–20

–30

36

06487-019

Figure 19. Negative Overvoltage Recovery

70

AV = +1 V

= 100mV p-p

IN

60

50

40

30

OVERSHOOT (%)

20

10

0

1 10 100 1k 10k

+OS

–OS

CAPACITANCE (pF )

Figure 17. Small Signal Overshoot vs. Load Capacitance

100k

06487-017

180

160

140

120

100

80

CMRR (dB)

60

40

20

0

–20

10 100 10k1k 100k 10M1M

FREQUENCY (Hz)

Figure 20. CMRR vs. Frequency

100M

06487-020

Rev. 0 | Page 8 of 12

AD8676

–

160

140

120

100

80

60

40

20

0

POWER SUPPL Y REJECTIO N RATIO (d B)

–20

10 100 10k1k 100k 10M1M

+PSRR

FREQUENCY (Hz)

–PSRR

Figure 21. Power Supply Rejection Ratio vs. Frequency

100M

06487-021

1000

TA = 25°C

100

(mV)

OUT

– V

S

V

10

1

0.001 0.01 0.1 1 10

LOAD CURRENT (mA)

SOURCE

SINK

Figure 24. Output Saturation Voltage vs. Output Load Current

100

06487-024

148

147

146

145

144

143

142

141

POWER SUPPL Y REJECTIO N RATIO (d B)

140

–40 –20 0 20 40 60 80 100

TEMPERATURE (° C)

Figure 22. Power Supply Rejection Ratio vs. Temperature

0.06

0.04

0.02

0

NOISE (µV)

–0.02

120

14.86

14.84

14.82

14.80

14.78

+SWING (V)

14.76

14.74

14.72

14.70 –40 –20 0 20 40 60 80 100

06487-022

V

OH

TEMPERATURE ( °C)

Figure 25. +Swing vs. Temperature, V

14.70

–14.75

–14.80

–14.85

–SWING (V)

–14.90

V

OL

VSY = ±15V R

= 2kΩ

L

OH

VSY = ±15V R

= 2kΩ

L

120

06487-025

–0.04

–0.06

012 4376589

TIME (s)

Figure 23. Voltage Noise (0.1 Hz to 10 Hz)

10

6487-023

–14.95

–15.00

–40 –20 0 20 40 60 80 1 00

TEMPERATURE (° C)

Figure 26. −Swing vs. Temperature, V

120

06487-026

OL

Rev. 0 | Page 9 of 12

AD8676

OUTLINE DIMENSIONS

5.00 (0.1968)

4.80 (0.1890)

4.00 (0.1574)

3.80 (0.1497)

0.25 (0.0098)

0.10 (0.0040)

COPLANARI TY

0.10

CONTROL LING DIMENSI ONS ARE IN MIL LIMET ERS; IN CH DIMENSI ONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIG N.

85

1

1.27 (0.0500)

SEATING

PLANE

COMPLIANT TO JEDE C STANDARDS MS-012-A A

BSC

6.20 (0. 2440)

5.80 (0. 2284)

4

1.75 (0.0688)

1.35 (0.0532)

0.51 (0.0201)

0.31 (0.0122)

8° 0°

0.25 (0.0098)

0.17 (0.0067)

Figure 27. 8-Lead Standard Small Outline Package [SOIC_N]

Narrow Body (R-8)

Dimensions shown in millimeters and (inches)

0.50 (0. 0196)

0.25 (0. 0099)

1.27 (0. 0500)

0.40 (0. 0157)

45°

0.95

0.85

0.75

0.15

0.00

060506-A

COPLANARITY

3.20

3.00

2.80

8

5

4

SEATING PLANE

5.15

4.90

4.65

1.10 MAX

0.23

0.08

8° 0°

3.20

3.00

1

2.80

PIN 1

0.65 BSC

0.38

0.22

0.10

COMPLIANT TO JEDEC STANDARDS MO-187-AA

Figure 28. 8-Lead Mini Small Outline Package [MSOP]

(RM-8)

Dimensions shown in millimeters

0.80

0.60

0.40

ORDERING GUIDE

Model Temperature Range Package Description Package Option Branding

AD8676ARMZ-R2 AD8676ARMZ-REEL AD8676ARZ AD8676ARZ-REEL AD8676ARZ-REEL7 AD8676BRMZ-R2 AD8676BRMZ-REEL AD8676BRZ AD8676BRZ-REEL AD8676BRZ-REEL7

1

Z = Pb-free part.

1

−40°C to +125°C 8-Lead Mini Small Outline Package [MSOP] RM-8 A13

1

−40°C to +125°C 8-Lead Mini Small Outline Package [MSOP] RM-8 A13