ANALOG DEVICES ADA4665-2 Service Manual

16 V, 1 MHz, CMOS Rail-to-Rail

FEATURES

Lower power at high voltage: 290 μA per amplifier typical
Low input bias current: 1 pA maximum
Wide bandwidth: 1.2 MHz typical
Slew rate: 1 V/μs typical
Offset voltage drift: 3 μV/°C typical
Single-supply operation: 5 V to 16 V
Dual-supply operation: ±2.5 V to ±8 V
Unity gain stable

APPLICATIONS

Portable systems
High density power budget systems
Medical equipment
Physiological measurement
Precision references
Multipole filters
Sensors
Transimpedance amplifiers
Buffer/level shifting

Input/Output Operational Amplifier

ADA4665-2

PIN CONFIGURATIONS

1

OUT A

OUT A

ADA4665-2

–IN A

2

+IN A

–IN A

+IN A

TOP VIEW

3

(Not to Scale)

V–

4

Figure 1. 8-Lead SOIC

1

ADA4665-2

2

TOP VIEW

3

(Not to Scale)

V–

4

Figure 2. 8-Lead MSOP

8

7

6

5

8

7

6

5

V+

OUT B

–IN B

+IN B

V+

OUT B

–IN B

+IN B

07650-001

07650-002

GENERAL DESCRIPTION

The ADA4665-2 is a rail-to-rail input/output dual amplifier
optimized for lower power budget designs. The ADA4665-2
offers a low supply current of 400 μA maximum per amplifier
at 25°C and 600 μA maximum per amplifier over the extended
industrial temperature range. This feature makes the ADA4665-2
well suited for low power applications. In addition, the ADA4665-2
has a very low bias current of 1 pA maximum, low offset voltage
drift of 3 μV/°C, and bandwidth of 1.2 MHz. The combination of
these features, together with a wide supply voltage range from
5 V to 16 V, allows the device to be used in a wide variety of
other applications, including process control, instrumentation
equipment, buffering, and sensor front ends. Furthermore, its
rail-to-rail input and output swing adds to its versatility. The
ADA4665-2 is specified from −40°C to +125°C and is available
in standard SOIC and MSOP packages.

Table 1. Low Cost Rail-to-Rail Input/Output Op Amps

Supply 5 V 16 V

Single AD8541
Dual AD8542 ADA4665-2
Quad AD8544

Table 2. Other Rail-to-Rail Input/Output Op Amps

Supply 5 V 16 V 36 V

Single AD8603 AD8663
Dual AD8607 AD8667 ADA4091-2
Quad AD8609 AD8669

Rev. 0

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. 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.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] ©2009 Analog Devices, Inc. All rights reserved.

ADA4665-2

TABLE OF CONTENTS

Features .............................................................................................. 1

Applications ....................................................................................... 1 

Pin Configurations ........................................................................... 1

General Description ......................................................................... 1

Revision History ............................................................................... 2

Specifications ..................................................................................... 3

Electrical Characteristics—16 V Operation ............................. 3

Electrical Characteristics—5 V Operation................................ 4

Absolute Maximum Ratings ............................................................ 5

REVISION HISTORY

1/09—Revision 0: Initial Version

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

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

Typical Performance Characteristics ..............................................6

Applications Information .............................................................. 15

Rail-to-Rail Input Operation .................................................... 15

Current Shunt Sensor ................................................................ 15

Active Filters ............................................................................... 15

Outline Dimensions ....................................................................... 17

Ordering Guide .......................................................................... 17

Rev. 0 | Page 2 of 20

ADA4665-2

SPECIFICATIONS

ELECTRICAL CHARACTERISTICS—16 V OPERATION

VSY = 16 V, VCM = VSY/2, TA = 25°C, unless otherwise noted.

Table 3.

Parameter Symbol Test Conditions/Comments Min Typ Max Unit

INPUT CHARACTERISTICS

Offset Voltage VOS V
V

−40°C ≤ TA ≤ +125°C 9 mV
Offset Voltage Drift ∆VOS/∆T −40°C ≤ TA ≤ +125°C 3 μV/°C
Input Bias Current IB 0.1 1 pA

−40°C ≤ TA ≤ +125°C 200 pA
Input Offset Current IOS 0.1 1 pA

−40°C ≤ TA ≤ +125°C 40 pA
Input Voltage Range −40°C ≤ TA ≤ +125°C 0 16 V
Common-Mode Rejection Ratio CMRR VCM = 0 V to 16 V 55 75 dB

−40°C ≤ TA ≤ +125°C 50 dB
Large Signal Voltage Gain AVO R

−40°C ≤ TA ≤ +125°C 75 dB
Input Resistance RIN 4 GΩ
Input Capacitance, Differential Mode C
Input Capacitance, Common Mode C

2 pF

INDM

7 pF

INCM

OUTPUT CHARACTERISTICS

Output Voltage High VOH R

−40°C ≤ TA ≤ +125°C 15.9 V
R

−40°C ≤ TA ≤ +125°C 15.8 V
Output Voltage Low VOL R

−40°C ≤ TA ≤ +125°C 15 mV
R

−40°C ≤ TA ≤ +125°C 150 mV
Short-Circuit Current ISC ±30 mA
Closed-Loop Output Impedance Z

f = 100 kHz, AV = 1 100 Ω

OUT

POWER SUPPLY

Power Supply Rejection Ratio PSRR VSY = 5 V to 16 V 70 95 dB

−40°C ≤ TA ≤ +125°C 65 dB
Supply Current per Amplifier ISY I

−40°C ≤ TA ≤ +125°C 600 μA

DYNAMIC PERFORMANCE

Slew Rate SR RL = 10 kΩ, CL = 50 pF, AV = 1 1 V/μs
Settling Time to 0.1% tS V
Gain Bandwidth Product GBP RL = 10 kΩ, CL = 50 pF, AV = 1 1.2 MHz
Phase Margin ΦM R

NOISE PERFORMANCE

Voltage Noise en p-p f = 0.1 Hz to 10 Hz 3 μV p-p
Voltage Noise Density en f = 1 kHz 32 nV/√Hz
f = 10 kHz 27 nV/√Hz
Current Noise Density in f = 1 kHz 50 fA/√Hz

= 16 V 1 4 mV

CM

= 0 V to 16 V 1 6 mV

CM

= 10 kΩ, VO = 0.5 V to 15 V 85 100 dB

L

= 100 kΩ to VCM 15.95 15.99 V

L

= 10 kΩ to VCM 15.9 15.95 V

L

= 100 kΩ to VCM 4 7.5 mV

L

= 10 kΩ to VCM 40 75 mV

L

= 0 mA 290 400 μA

O

= 1 V step, RL = 2 kΩ, CL = 50 pF 6.5 μs

IN

= 10 kΩ, CL = 50 pF, AV = 1 50 Degrees

L

Rev. 0 | Page 3 of 20

ADA4665-2

ELECTRICAL CHARACTERISTICS—5 V OPERATION

VSY = 5 V, VCM = VSY/2, TA = 25°C, unless otherwise noted.

Table 4.

Parameter Symbol Test Conditions/Comments Min Typ Max Unit

INPUT CHARACTERISTICS

Offset Voltage VOS V
V

−40°C ≤ TA ≤ +125°C 9 mV
Offset Voltage Drift ∆VOS/∆T −40°C ≤ TA ≤ +125°C 3 μV/°C
Input Bias Current IB 0.1 1 pA

−40°C ≤ TA ≤ +125°C 100 pA
Input Offset Current IOS 0.1 1 pA

−40°C ≤ TA ≤ +125°C 10 pA
Input Voltage Range −40°C ≤ TA ≤ +125°C 0 5 V
Common-Mode Rejection Ratio CMRR VCM = 0 V to 5 V 55 75 dB

−40°C ≤ TA ≤ +125°C 50 dB
Large Signal Voltage Gain AVO R

−40°C ≤ TA ≤ +125°C 75 dB
Input Resistance RIN 1 GΩ
Input Capacitance, Differential Mode C
Input Capacitance, Common Mode C

2 pF

INDM

7 pF

INCM

OUTPUT CHARACTERISTICS

Output Voltage High VOH R

−40°C ≤ TA ≤ +125°C 4.9 V
R

−40°C ≤ TA ≤ +125°C 4.8 V
Output Voltage Low VOL R

−40°C ≤ TA ≤ +125°C 10 mV
R

−40°C ≤ TA ≤ +125°C 100 mV
Short-Circuit Current ISC ±8 mA
Closed-Loop Output Impedance Z

f = 100 kHz, AV = 1 100 Ω

OUT

POWER SUPPLY

Power Supply Rejection Ratio PSRR VSY = 5 V to 16 V 70 95 dB

−40°C ≤ TA ≤ +125°C 65 dB
Supply Current per Amplifier ISY I

−40°C ≤ TA ≤ +125°C 600 μA

DYNAMIC PERFORMANCE

Slew Rate SR RL = 10 kΩ, CL = 50 pF, AV = 1 1 V/μs
Settling Time to 0.1% tS V
Gain Bandwidth Product GBP RL = 10 kΩ, CL = 50 pF, AV = 1 1.2 MHz
Phase Margin ΦM R

NOISE PERFORMANCE

Voltage Noise en p-p f = 0.1 Hz to 10 Hz 3 μV p-p
Voltage Noise Density en f = 1 kHz 32 nV/√Hz
f = 10 kHz 27 nV/√Hz
Current Noise Density in f = 1 kHz 50 fA/√Hz

= 5 V 1 4 mV

CM

= 0 V to 5 V 1 6 mV

CM

= 10 kΩ, VO = 0.5 V to 4.5 V 85 100 dB

L

= 100 kΩ to VCM 4.95 4.99 V

L

= 10 kΩ to VCM 4.9 4.96 V

L

= 100 kΩ to VCM 3 5 mV

L

= 10 kΩ to VCM 30 50 mV

L

= 0 mA 270 350 μA

O

= 1 V step, RL = 2 kΩ, CL = 50 pF 6.5 μs

IN

= 10 kΩ, CL = 50 pF, AV = 1 50 Degrees

L

Rev. 0 | Page 4 of 20

ADA4665-2

ABSOLUTE MAXIMUM RATINGS

Table 5.

Parameter Rating

Supply Voltage 16.5 V
Input Voltage1 GND − 0.3 V to VSY + 0.3 V
Input Current ±10 mA
Differential Input Voltage ±VSY
Output Short-Circuit Duration to GND Indefinite
Storage Temperature Range −65°C to +150°C
Operating Temperature Range −40°C to +125°C
Junction Temperature Range −65°C to +150°C
Lead Temperature (Soldering, 60 sec) 300°C

1

The input pins have clamp diodes to the power supply pins.

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.

THERMAL RESISTANCE

θJA is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages. This
value was measured using a 4-layer JEDEC standard printed
circuit board.

Table 6. Thermal Resistance

Package Type θJA θ

8-Lead SOIC_N (R-8) 158 43 °C/W
8-Lead MSOP (RM-8) 186 52 °C/W

Unit

JC

ESD CAUTION

Rev. 0 | Page 5 of 20

ADA4665-2

TYPICAL PERFORMANCE CHARACTERISTICS

TA = 25°C, unless otherwise noted.

70

60

VSY = 5V
V

= VSY/2

CM

70

60

VSY = 16V
V

= VSY/2

CM

50

40

30

20

NUMBER OF AMPLIFIERS

10

0

–6 –5 –4 –3 –2 –1 0123456

V

(mV)

OS

Figure 3. Input Offset Voltage Distribution

10

9

8

7

6

5

4

3

NUMBER OF AMPLIFIERS

2

1

0

01234 5678910

TCV

OS

(µV/°C)

VSY = 5V
–40°C ≤ T

≤ +125°C

A

Figure 4. Input Offset Voltage Drift Distribution

50

40

30

20

NUMBER OF AMPLIFIERS

10

0

–6 –5 –4 –3 –2 –1 01 23456

07650-006

(mV)

V

OS

07650-003

Figure 6. Input Offset Voltage Distribution

10

9

8

7

6

5

4

3

NUMBER OF AMPLIFIERS

2

1

0

012345678910

07650-007

TCV

OS

(µV/°C)

VSY = 16V
–40°C ≤ T

≤ +125°C

A

07650-004

Figure 7. Input Offset Voltage Drift Distribution

5

4

3

2

1

(mV)

OS

0

V

–1

–2

–3

–4

01 2 3 4 5

(V)

V

CM

VSY = 5V

Figure 5. Input Offset Voltage vs. Common-Mode Voltage

07650-008

5

4

3

2

1

(mV)

OS

0

V

–1

–2

–3

–4

0 2 4 6 8 10 12 14 16

(V)

V

CM

VSY = 16V

Figure 8. Input Offset Voltage vs. Common-Mode Voltage

0-005
0765

Rev. 0 | Page 6 of 20

ADA4665-2

TA = 25°C, unless otherwise noted.

100

1k

IB+
I

–

B

VSY = 5V

100

1k

IB+

–

I

B

= 16V

V

SY

10

1

(pA)

B

I

0.1

0.01

0.001
25 50 75 100 125

TEMPERATURE (° C)

Figure 9. Input Bias Current vs. Temperature

1k

100

125°C

105°C

85°C

25°C

(pA)

B

I

10

1

0.1

0.01

0.001

VSY = 5V

10

1

(pA)

B

I

0.1

0.01

0.001
25 50 75 100 125

07650-012

TEMPERATURE (° C)

07650-009

Figure 12. Input Bias Current vs. Temperature

(pA)

B

I

100

0.1

0.01

0.001

1k

125°C

10

1

105°C

85°C

25°C

VSY = 16V

0.0001
0 12345

V

(V)

CM

Figure 10. Input Bias Current vs. Input Common-Mode Voltage

10k

VSY = 5V

1k

100

) TO SUPPLY RAIL (mV)

OH

10

1

OUTPUT VOL TAGE (V

0.1

0.001 0.01 0.1 1 10 100

LOAD CURRENT (mA)

Figure 11. Output Voltage (VOH) to Supply Rail vs. Load Current

–40°C
+25°C
+85°C
+125°C

0.0001
0 2 4 6 8 10 12 14 16

07650-013

V

(V)

CM

07650-010

Figure 13. Input Bias Current vs. Input Common-Mode Voltage

10k

VSY = 16V

1k

100

) TO SUPPLY RAIL (mV)

10

OH

1

0.1

OUTPUT VOLTAGE (V

0.01

0.001 0.01 0.1 1 10 100

07650-014

LOAD CURRENT (mA)

–40°C
+25°C
+85°C
+125°C

0-011
0765

Figure 14. Output Voltage (VOH) to Supply Rail vs. Load Current

Rev. 0 | Page 7 of 20

ADA4665-2

TA = 25°C, unless otherwise noted.

10k

VSY = 5V

10k

VSY = 16V

1k

100

) TO SUPPLY RAIL (mV)

OL

10

1

OUTPUT VOLTAGE (V

0.1

0.001 0.01 0.1 1 10 100

LOAD CURRENT (mA)

–40°C
+25°C
+85°C
+125°C

Figure 15. Output Voltage (VOL) to Supply Rail vs. Load Current

5.00

4.99

4.98

(V)

OH

4.97

4.96

4.95

4.94

OUTPUT VOLTAGE, V

VSY = 5V

4.93

4.92
–50 –25 0 25 50 75 100 125

RL = 100kΩ

RL = 10kΩ

TEMPERATURE (°C)

Figure 16. Output Voltage (VOH) vs. Temperature

1k

100

) TO SUPPLY RAIL (mV)

OL

10

–40°C

1

OUTPUT VO LTAGE (V

0.1

0.001 0.01 0.1 1 10 100

07650-018

LOAD CURRENT (mA)

+25°C
+85°C
+125°C

07650-015

Figure 18. Output Voltage (VOL) to Supply Rail vs. Load Current

16.00

15.99

15.98

(V)

15.97

OH

15.96

15.95

15.94

15.93

OUTPUT VOLTAGE, V

15.92
VSY = 16V

15.91

15.90

–50 –25 0 25 50 75 100 125

07650-019

RL = 100kΩ

RL = 10kΩ

TEMPERATURE (°C)

07650-016

Figure 19. Output Voltage (VOH) vs. Temperature

60

VSY = 5V

50

(mV)

40

OL

30

20

OUTPUT VOLTAGE, V

10

0

–50 –25 0 25 50 75 100 125

RL = 10kΩ

RL = 100kΩ

TEMPERATURE (° C)

Figure 17. Output Voltage (VOL) vs. Temperature

07650-020

60

VSY = 16V

50

(mV)

40

OL

30

20

OUTPUT VOLTAGE, V

10

0

–50 –25 0 25 50 75 100 125

RL = 10kΩ

RL = 100kΩ

TEMPERATURE (° C)

Figure 20. Output Voltage (VOL) vs. Temperature

0-017
0765

Rev. 0 | Page 8 of 20

ADA4665-2

TA = 25°C, unless otherwise noted.

= 10kΩ
= 50pF

180

135

90

80

60

40

PHASE

VSY = 16V
R

L

C

L

80

60

40

PHASE

VSY = 5V
R

L

C

L

= 10kΩ
= 50pF

180

135

90

20

0

OPEN-LOOP GAIN (dB)

–20

–40

1k 10k 100k 1M 10M

FREQUENCY (Hz)

GAIN

Figure 21. Open-Loop Gain and Phase vs. Frequency

50

AV = 100

40

30

AV = 10

20

10

AV = 1

0

–10

–20

CLOSED-LOOP GAIN (dB)

–30

–40

–50

100 1k 10k 100 k 1M 10M 100M

FREQUENCY (Hz)

VSY = 5V
R

Figure 22. Closed-Loop Gain vs. Frequency

= 10kΩ

L

45

0

–45

–90

07650-025

PHASE (Degrees)

07650-024

20

0

OPEN-LOOP GAIN (dB)

–20

–40

1k 10k 100k 1M 10M

FREQUENCY (Hz)

GAIN

Figure 24. Open-Loop Gain and Phase vs. Frequency

50

AV = 100

40

30

AV = 10

20

10

AV = 1

0

–10

–20

CLOSED-LOOP GAIN (dB)

–30

–40

–50

100 1k 10k 100 k 1M 10M 100M

FREQUENCY (Hz)

VSY = 16V
R

Figure 25. Closed-Loop Gain vs. Frequency

= 10kΩ

L

45

0

–45

–90

PHASE (Degrees)

07650-021

07650-022

1k

VSY = 5V

100

10

(Ω)

OUT

Z

0.1

0.01

AV = 100

AV = 10

1

AV = 1

10 100 1k 10k 100k 1M 10M

FREQUENCY (Hz)

Figure 23. Output Impedance vs. Frequency

07650-026

1k

VSY = 16V

100

AV = 100

10

(Ω)

OUT

Z

0.1

0.01

AV = 10

1

AV = 1

10 100 1k 10k 100k 1M 10M

FREQUENCY (Hz)

Figure 26. Output Impedance vs. Frequency

0-023
0765

Rev. 0 | Page 9 of 20

ADA4665-2

TA = 25°C, unless otherwise noted.

100

VSY = 5V

90

100

VSY = 16V

90

80

70

CMRR (dB)

60

50

40

100 1k 10k 100k 1M

FREQUENCY (Hz)

Figure 27. CMRR vs. Frequency

120

100

80

60

40

PSRR (dB)

20

PSRR+

0

PSRR–

–20

100 1k 10k 100k 10M1M

FREQUENCY (Hz)

VSY = 5V

Figure 28. PSRR vs. Frequency

80

70

CMRR (dB)

60

50

40

100 1k 10k 100k 1M

07650-030

FREQUENCY (Hz)

07650-027

Figure 30. CMRR vs. Frequency

120

100

80

60

40

PSRR (dB)

20

0

–20

07650-031

PSRR+
PSRR–

100 1k 10k 100k 1M 10M

FREQUENCY (Hz)

VSY = 16V

07650-028

Figure 31. PSRR vs. Frequency

80

VSY = 5V

= 100mV p-p

V

IN

70

= 10kΩ

R

L

60

50

40

30

OVERSHOOT (%)

20

10

0

10 100 1k

CAPACITANCE (pF )

OS+

OS–

Figure 29. Small Signal Overshoot vs. Load Capacitance

07650-032

80

VSY = 16V

= 100mV p-p

V

IN

70

= 10kΩ

R

L

60

50

40

30

OVERSHOOT (%)

20

10

0

10 100 1k

CAPACITANCE (pF )

OS+

OS–

Figure 32. Small Signal Overshoot vs. Load Capacitance

0-029
0765

Rev. 0 | Page 10 of 20

ADA4665-2

TA = 25°C, unless otherwise noted.

VSY = 5V

= 2kΩ

R

L

= 10pF

C

L

VOLTAGE (1V/DIV)

TIME (100µ s/DIV)

07650-036

VOLTAGE (5V/DIV)

TIME (100µ s/DIV)

Figure 33. Large Signal Transient Response Figure 36. Large Signal Transient Response

VSY = 5V

= 2kΩ

R

L

= 10pF

C

L

VOLTAGE (50mV/DIV)

VOLTAGE (50mV/DIV)

VSY = 16V

= 2kΩ

R

L

= 10pF

C

L

VSY = 16V

= 2kΩ

R

L

= 10pF

C

L

07650-033

TIME (100µ s/DIV)

TIME (20µ s/DIV)

INPUT

OUTPUT

VSY = ±8V

07650-034

10

5

0

–5

OUTPUT VOLTAGE (V)

07650-035

INPUT VOLTAGE (mV)

–50

–100

TIME (100µ s/DIV)

Figure 34. Small Signal Transient Response

50

0

TIME (20µs/DIV)

VSY = ±2.5V

INPUT

OUTPUT

Figure 35. Positive Overload Recovery

07650-037

Figure 37. Small Signal Transient Response

)

50

0

–50

–100

INPUT VOLTAGE (mV

3

2

1

0

UTPUT VOLTAGE (V)
O

–1

07650-038

Figure 38. Positive Overload Recovery

Rev. 0 | Page 11 of 20

ADA4665-2

TA = 25°C, unless otherwise noted.

)

150

VSY = ±2.5V

100

150

VSY = ±8V

100

50

0

INPUT VOLTAGE (mV)

TIME (20µs/DIV)

INPUT

OUTPUT

0

–1

–2

TPUT VOLTAGE (V)

–3

OU

07650-042

Figure 39. Negative Overload Recovery

VSY = 5V
R

= 2kΩ

L

C

= 50pF

L

INPUT

VOLTAGE (500mV/DIV)

ERROR

BAND

OUTPUT

+5mV

0
–5mV

50

0

INPUT VOLTAGE (mV

TIME (20µs/DIV)

INPUT

OUTPUT

0

–5

–10

OUTPUT VOLTAGE (V)

07650-039

Figure 42. Negative Overload Recovery

VSY = 16V
R

= 2kΩ

L

C

= 50pF

L

INPUT

VOLTAGE (500mV/DIV)

ERROR

BAND

OUTPUT

+5mV

0
–5mV

TIME (2µs/DIV)

TIME (2µs/DIV)

INPUT

OUTPUT

VSY = 16V
R

= 2kΩ

L

C

= 50pF

L

+5mV

0
–5mV

07650-040

0-041
0765

VOLTAGE (500mV/DIV)

TIME (2µs/DIV)

Figure 40. Negative Settling Time to 0.1%

ERROR
BAND

TIME (2µs/DIV)

Figure 41. Positive Settling Time to 0.1%

INPUT

OUTPUT

VSY = 5V
R

= 2kΩ

L

C

= 50pF

L

+5mV

0
–5mV

07650-043

Figure 43. Negative Settling Time to 0.1%

VOLTAGE (500mV/DIV)

ERROR

BAND

07650-044

Figure 44. Positive Settling Time to 0.1%

Rev. 0 | Page 12 of

20

ADA4665-2

TA = 25°C, unless otherwise noted.

100

VSY = 5V

100

VSY = 16V

Hz)

VOLTAGE NOISE DENSI TY (nV/

10

100 1k 10k 100k

FREQUENCY (Hz)

Figure 45. Voltage Noise Density vs. Frequency

VSY = 5V

INPUT VOLTAGE NOISE (1µV/DIV)

Hz)

VOLTAGE NOISE DENSI TY (nV/

10

100 1k 10k 100k

07650-048

FREQUENCY (Hz)

07650-045

Figure 48. Voltage Noise Density vs. Frequency

VSY = 16V

INPUT VOLTAGE NOISE (1µV/DIV)

TIME (2s/DIV)

Figure 46. 0.1 Hz to 10 Hz Noise

900

800

700

600

500

400

300

SUPPLY CURRENT (µA)

200

100

0

0 2 4 6 8 10 12 14 16

SUPPLY VOLTAGE (V)

+125°C

+85°C

+25°C

–40°C

Figure 47. Supply Current vs. Supply Voltage

07650-049

Figure 49. 0.1 Hz to 10 Hz Noise

900

800

700

600

500

SUPPLY CURRENT (µA)

400

300

–50 –25 0 25 50 75 100 125

07650-047

Figure 50. Supply Current vs. Temperature

TIME (2s/DIV)

VSY = 16V

VSY = 5V

TEMPERATURE (° C)

07650-046

0-050
0765

Rev. 0 | Page 13 of

20

ADA4665-2

TA = 25°C, unless otherwise noted.

–20

–40

0

VSY = 5V
R

= 10kΩ

L

A

= –100

V

100kΩ

1kΩ

–20

–40

0

VSY = 16V

= 10kΩ

R

L

= –100

A

V

100kΩ

1kΩ

–60

–80

–100

–120

CHANNEL SEPARATIO N (dB)

–140

–160

100 1k 10k 100k

FREQUENCY (Hz)

Figure 51. Channel Separation vs. Frequency

1

VSY = 5V

= 10kΩ

R

L

= 1

A

V

0.1

THD + NOISE (%)

0.01

VIN = 1V p-p
V

0.001
10 100 1k 10k 100k

FREQUENCY (Hz)

Figure 52. THD + Noise vs. Frequency

= 4V p-p

IN

VIN = 1V p-p
V

= 4V p-p

IN

–60

–80

–100

–120

CHANNEL SEPARATIO N (dB)

–140

–160

100 1k 10k 100k

07650-053

FREQUENCY (Hz)

VIN = 1V p-p

= 5V p-p

V

IN

= 15V p-p

V

IN

07650-051

Figure 53. Channel Separation vs. Frequency

1

VSY = 16V
R

= 10kΩ

L

A

= 1

V

0.1

THD + NOISE (%)

0.01

VIN = 1V p-p
V

= 5V p-p

IN

V

= 15V p-p

0.001
10 100 1k 10k 100k

07650-054

FREQUENCY (Hz)

IN

0-052
0765

Figure 54. THD + Noise vs. Frequency

Rev. 0 | Page 14 of

20

ADA4665-2

APPLICATIONS INFORMATION

RAIL-TO-RAIL INPUT OPERATION

The ADA4665-2 is a unity-gain stable CMOS operational
amplifier designed with rail-to-rail input/output swing
capability to optimize performance. The rail-to-rail input
feature is vital to maintain the wide dynamic input voltage
range and to maximize signal swing to both supply rails. For
example, the rail-to-rail input feature is extremely useful in
buffer applications where the input voltage must cover both
the supply rails.

The input stage has two input differential pairs, nMOS and
pMOS. When the input common-mode voltage is at the low
end of the input voltage range, the pMOS input differential pair
is active and amplifies the input signal. As the input common­mode voltage is slowly increased, the pMOS differential pair
gradually turns off while the nMOS input differential pair turns
on. This transition is inherent to all rail-to-rail input amplifiers
that use the dual differential pairs topology. For the ADA4665-2,
this transition occurs approximately 1 V away from the positive
rail and results in a change in offset voltage due to the different
offset voltages of the differential pairs (see Figure 5 and Figure 8).

CURRENT SHUNT SENSOR

Many applications require the sensing of signals near the
positive or the negative rails. Current shunt sensors are one
such application and are mostly used for feedback control
systems. They are also used in a variety of other applications,
including power metering, battery fuel gauging, and feedback
controls in electrical power steering. In such applications, it is
desirable to use a shunt with very low resistance to minimize
the series voltage drop. This not only minimizes wasted power,
but also allows the measurement of high currents while saving
power. The ADA4665-2 provides a low cost solution for
implementing current shunt sensors.

Figure 55 shows a low-side current sensing circuit, and Figure 56
shows a high-side current sensing circuit using the ADA4665-2.
A typical shunt resistor of 0.1 Ω is used. In these circuits, the
difference amplifier amplifies the voltage drop across the shunt
resistor by a factor of 100. For true difference amplification,
matching of the resistor ratio is very important, where R1/R2 =
R3/R4. The rail-to-rail feature of the ADA4665-2 allows the
output of the op amp to almost reach 16 V (the power supply of
the op amp). This allows the current shunt sensor to sense up to
approximately 1.6 A of current.

I

16V

SUPPLY

V

OUT

I

R2

*

1MΩ

16V

10kΩ

1/2

R

S

0.1Ω

R1

R

L

ADA4665-2

R4

1MΩ

= AMPLIF IER GAIN × VOLTAGE ACROSS R

*V

OUT

= 100 × RS × I
= 10 × I

R3

10kΩ

S

07650-055

Figure 55. Low-Side Current Sensing Circuit

R

S

R3

10kΩ

0.1Ω

R

L

16V

SUPPLY

V

OUT

I

I

R4

1MΩ

16V

*

1/2

ADA4665-2

R2

1MΩ

= AMPLIFI ER GAIN × VO LTAGE ACRO SS R

*V

OUT

= 100 × RS × I
= 10 × I

R1

10kΩ

S

07650-056

Figure 56. High-Side Current Sensing Circuit

ACTIVE FILTERS

The ADA4665-2 is well suited for active filter designs. An active
filter requires an op amp with a unity-gain bandwidth at least
100 times greater than the product of the corner frequency, f
and the quality factor, Q. An example of an active filter is the
Sallen-Key, one of the most widely used filter topologies. This
topology gives the user the flexibility of implementing either
a low-pass or a high-pass filter by simply interchanging the
resistors and capacitors. To achieve the desired performance,
1% or better component tolerances are usually required.

Figure 57 shows a two-pole low-pass filter. It is configured as a
unity-gain filter with cutoff frequency at 10 kHz. Resistor and
capacitor values are chosen to give a quality factor, Q, of 1/√2
for a Butterworth filter, which has maximally flat pass-band
frequency response. Figure 58 shows the frequency response of
the low-pass Sallen-Key filter. The response falls off at a rate of
40 dB per decade after the cutoff frequency of 10 kHz.

,

c

Rev. 0 | Page 15 of 20

ADA4665-2

R1

22.5kΩ

V

IN

22.5kΩ

C2

0.5nF

R2

C1

1nF

+V

SY

1/2

ADA4665-2

–V

SY

V

OUT

07650-057

Figure 57. Two-Pole Low-Pass Filter

When R1 = R2 and C1 = 2C2, the values of Q and the cutoff
frequency are calculated as follows:

C2C1R2R1

Q =

f

c

π=2

)( R2R1C2 +

1

2R1 R2 C1 C

10

0

–10

–20

–30

GAIN (dB)

–40

–50

–60

100 1k 10k 100k 1M

FREQUENCY (Hz)

Figure 58. Low-Pass Filter: Gain vs. Frequency

Figure 59 shows a two-pole high-pass filter, with cutoff frequency
at 10 kHz and quality factor, Q, of 1/√2.

C1

0.5nF

V

IN

0.5nF

45kΩ

C2

R2

Figure 59. Two-Pole High-Pass Filter

R1

22.5kΩ

+V

SY

1/2

ADA4665-2

–V

SY

V

OUT

07650-059

When R2 = 2R1 and C1 = C2, the values of Q and the cutoff
frequency are calculated as follows:

C2C1R2R1

Q+=

f

c

π=2

)( C2C1R1

1

C2C1R2R1

10

0

–10

–20

–30

–40

–50

–60

GAIN (dB)

–70

–80

–90

–100

07650-058

–110

–120

10 100 1k 10k 100k 1M

FREQUENCY (Hz)

Figure 60. High-Pass Filter: Gain vs. Frequency

07650-060

Rev. 0 | Page 16 of 20

ADA4665-2

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)

COPLANARITY

0.10

CONTROLL ING DIMENSI ONS ARE IN MILLIMETERS; INCH DI MENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRI ATE FOR USE IN DESIGN.

85

1

1.27 (0.0500)

SEATING

PLANE

COMPLIANT TO JEDEC STANDARDS MS-012-A A

BSC

6.20 (0.2441)

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)

0.50 (0.0196)

0.25 (0.0099)

1.27 (0.0500)

0.40 (0.0157)

45°

012407-A

Figure 61. 8-Lead Standard Small Outline Package [SOIC_N]

Narrow Body

(R-8)

Dimensions shown in millimeters and (inches)

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°

0.80

0.60

0.40

3.20

3.00

2.80

PIN 1

0.95

0.85

0.75

0.15

0.00

COPLANARITY

0.10

1

0.38

0.22

0.65 BSC

COMPLIANT TO JEDEC STANDARDS MO -187-AA

Figure 62. 8-Lead Mini Small Outline Package [MSOP]

(RM-8)

Dimensions shown in millimeters

ORDERING GUIDE

Model Temperature Range Package Description Package Option Branding

ADA4665-2ARZ
ADA4665-2ARZ-RL
ADA4665-2ARZ-R7
ADA4665-2ARMZ
ADA4665-2ARMZ-R7
ADA4665-2ARMZ-RL

1

Z = RoHS Compliant Part.

1

−40°C to +125°C 8-Lead SOIC_N R-8

1

1

1

−40°C to +125°C 8-Lead SOIC_N R-8

−40°C to +125°C 8-Lead SOIC_N R-8

−40°C to +125°C 8-Lead MSOP RM-8 A26

1

−40°C to +125°C 8-Lead MSOP RM-8 A26

1

−40°C to +125°C 8-Lead MSOP RM-8 A26

Rev. 0 | Page 17 of 20

ADA4665-2

NOTES

Rev. 0 | Page 18 of 20

ADA4665-2

NOTES

Rev. 0 | Page 19 of 20

ADA4665-2

NOTES

©2009 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D07650-0-1/09(0)

Rev. 0 | Page 20 of 20