a

Precision Micropower Single-Supply Operational Amplifiers OP777/OP727/OP747

FEATURES Low Offset Voltage: 100
V Max Low Input Bias Current: 10 nA Max Single-Supply Operation: 2.7 V to 30 V Dual-Supply Operation: 1.35 V to 15 V Low Supply Current: 300
A/Amp Max Unity Gain Stable No Phase Reversal

FUNCTIONAL BLOCK DIAGRAMS 14-Lead SOIC (R-14)

8-Lead MSOP (RM-8) 1

NC IN IN V

8

NC V+ OUT NC

OP777 4

5

NC = NO CONNECT

APPLICATIONS Current Sensing (Shunt) Line or Battery-Powered Instrumentation Remote Sensors Precision Filters

OUT A 1

14

OUT D

–IN A 2

13

–IN D

IN A 3

12

IN D

V 4

V– TOP VIEW (Not to Scale) 10 IN B 5 IN C

8-Lead SOIC (R-8)

NC 1 IN 2

OP777

OP747

11

–IN B 6

9

–IN C

OUT B 7

8

OUT C

8 NC 7 V+

+IN 3

6 OUT

V 4

5 NC

14-Lead TSSOP (RU-14)

GENERAL DESCRIPTION

The OP777, OP727, and OP747 are precision single, dual, and quad rail-to-rail output single supply amplifiers featuring micropower operation and rail-to-rail output ranges. These amplifiers provide improved performance over the industry-standard OP07 with ±15 V supplies, and offer the further advantage of true single-supply operation down to 2.7 V, and smaller package options than any other high-voltage precision bipolar amplifier. Outputs are stable with capacitive loads of over 500 pF. Supply current is less than 300 µA per amplifier at 5 V. 500 Ω series resistors protect the inputs, allowing input signal levels several volts above the positive supply without phase reversal.

NC = NO CONNECT

8-Lead TSSOP (RU-8) OUT A 1

8

7 OUT B OP727 TOP VIEW IN A 3 (Not to Scale) 6 –IN B 5

14

OUT D

–IN A 2

13

–IN D

IN A 3

12

IN D

V 4

OP747

TOP VIEW 11 V– (Not to Scale) 10 IN B 5 IN C –IN B 6

9

–IN C

7

8

OUT C

V

–IN A 2

V– 4

OUT A 1

OUT B

IN B

Applications for these amplifiers include both line-powered and portable instrumentation, remote sensor signal conditioning, and precision filters. The OP777, OP727, and OP747 are specified over the extended industrial (–40°C to +85°C) temperature range. The OP777, single, is available in 8-lead MSOP and 8-lead SOIC packages. The OP727, dual, is available in an 8-lead TSSOP. The OP747, quad, is available in 14-lead TSSOP and narrow 14-lead SO packages. Surface-mount devices in TSSOP and MSOP packages are available in tape and reel only.

REV. B 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.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781/329-4700 World Wide Web Site: http://www.analog.com Fax: 781/326-8703 © Analog Devices, Inc., 2001

OP777/OP727/OP747–SPECIFICATIONS ELECTRICAL CHARACTERISTICS (@ V = 5.0 V, V S

CM

= 2.5 V, TA = 25C unless otherwise noted.)

Parameter

Symbol

Conditions

INPUT CHARACTERISTICS Offset Voltage OP777

VOS

IB IOS

+25
C < TA < +85
C –40°C < TA < +85°C +25
C < TA < +85
C –40°C < TA < +85°C –40°C < TA < +85°C –40°C < TA < +85°C

CMRR AVO ∆VOS /∆T ∆VOS /∆T

VCM = 0 V to 4 V RL = 10 kΩ, VO = 0.5 V to 4.5 V –40°C < TA < +85°C –40°C < TA < +85°C

OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Output Circuit

VOH VOL IOUT

IL = 1 mA, –40°C to +85°C IL = 1 mA, –40°C to +85°C VDROPOUT < 1 V

4.88

POWER SUPPLY Power Supply Rejection Ratio Supply Current/Amplifier OP777

PSRR ISY

VS = 3 V to 30 V VO = 0 V –40°C < TA < +85°C VO = 0 V –40°C < TA < +85°C

120

DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product

SR GBP

RL = 2 kΩ

0.2 0.7

V/µs MHz

NOISE PERFORMANCE Voltage Noise Voltage Noise Density Current Noise Density

enp-p en in

0.1 Hz to 10 Hz f = 1 kHz f = 1 kHz

0.4 15 0.13

µV p-p nV/√Hz pA/√Hz

Offset Voltage OP727/OP747 Input Bias Current Input Offset Current Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Offset Voltage Drift OP777 Offset Voltage Drift OP727/OP747

Supply Current/Amplifier OP727/OP747

Min

0 104 300

Typ

Max

Unit

20 50 30 60 5.5 0.1

100 200 160 300 11 2 4

µV µV µV µV nA nA V dB V/mV µV/°C µV/°C

110 500 0.3 0.4

1.3 1.5

4.91 126 ± 10 130 220 270 235 290

140

V mV mA

270 320 290 350

dB µA µA µA µA

NOTES Typical specifications: >50% of units perform equal to or better than the “typical” value. Specifications subject to change without notice.

ABSOLUTE MAXIMUM RATINGS 1, 2

Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 V Input Voltage . . . . . . . . . . . . . . . . . . . . –VS – 5 V to +VS + 5 V Differential Input Voltage . . . . . . . . . . . . . . ± Supply Voltage Output Short-Circuit Duration to GND . . . . . . . . . Indefinite Storage Temperature Range RM, R, RU Packages . . . . . . . . . . . . . . . . –65°C to +150°C Operating Temperature Range OP777/OP727/OP747 . . . . . . . . . . . . . . . –40°C to +85°C Junction Temperature Range RM, R, RU Packages . . . . . . . . . . . . . . . . –65°C to +150°C Lead Temperature Range (Soldering, 60 sec) . . . . . . . 300°C Electrostatic Discharge (Human Body Model) . . . . 2000 V max

Package Type

JA3

JC

Unit

8-Lead MSOP (RM) 8-Lead SOIC (R) 8-Lead TSSOP (RU) 14-Lead SOIC (R) 14-Lead TSSOP (RU)

190 158 240 120 180

44 43 43 36 35

°C/W °C/W °C/W °C/W °C/W

NOTES 1 Absolute maximum ratings apply at 25°C, unless otherwise noted. 2 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 listed in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. 3 θJA is specified for worst-case conditions, i.e., θJA is specified for device soldered in circuit board for surface-mount packages.

–2–

REV. B

OP777/OP727/OP747 ELECTRICAL CHARACTERISTICS (@ 15 V, V

CM

= 0 V, TA = 25C unless otherwise noted.)

Parameter

Symbol

Conditions

INPUT CHARACTERISTICS Offset Voltage OP777

VOS

Offset Voltage OP727/OP747

VOS

Input Bias Current Input Offset Current Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Offset Voltage Drift OP777 Offset Voltage Drift OP727/OP747

IB IOS

+25°C < TA < +85°C –40°C < TA < +85°C +25°C < TA < +85°C –40°C < TA < +85°C –40°C < TA < +85°C –40°C < TA < +85°C

CMRR AVO ∆VOS /∆T ∆VOS /∆T

VCM = –15 V to +14 V RL = 10 kΩ, VO = –14.5 V to +14.5 V –40°C < TA < +85°C –40°C < TA < +85°C

OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Output Circuit

VOH VOL IOUT

IL = 1 mA, –40°C to +85°C IL = 1 mA, –40°C to +85°C

14.9

14.94 –14.94 –14.9 ± 30

V V mA

POWER SUPPLY Power Supply Rejection Ratio Supply Current/Amplifier OP777

PSRR ISY

VS = ± 1.5 V to ± 15 V VO = 0 V –40°C < TA < +85°C VO = 0 V –40°C < TA < +85°C

120

130 300 350 320 375

dB µA µA µA µA

DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product

SR GBP

RL = 2 kΩ

0.2 0.7

V/µs MHz

NOISE PERFORMANCE Voltage Noise Voltage Noise Density Current Noise Density

enp-p en in

0.1 Hz to 10 Hz f = 1 kHz f = 1 kHz

0.4 15 0.13

µV p-p nV/√Hz pA/√Hz

Supply Current/Amplifier OP727/747

Min

–15 110 1,000

Typ

Max

Unit

30 50 30 50 5 0.1

100 200 160 300 10 2 +14

µV µV µV µV nA nA V dB V/mV µV/°C µV/°C

120 2,500 0.3 0.4

1.3 1.5

350 400 375 450

Specifications subject to change without notice.

ORDERING GUIDE

Model

Temperature Range

Package Description

Package Option

Branding Information

OP777ARM OP777AR OP727ARU OP747AR OP747ARU

–40°C to +85°C –40°C to +85°C –40°C to +85°C –40°C to +85°C –40°C to +85°C

8-Lead MSOP 8-Lead SOIC 8-Lead TSSOP 14-Lead SOIC 14-Lead TSSOP

RM-8 R-8 RU-8 R-14 RU-14

A1A

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 OP777/OP727/OP747 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.

REV. B

–3–

WARNING! ESD SENSITIVE DEVICE

OP777/OP727/OP747–Typical Performance Characteristics 180 160 140 120 100 80 60

30

220 VSY = 5V VCM = 2.5V TA = 25C

200 180 160 140 120 100 80 60

40

40

20

20

0 100 8060 4020 0 20 40 60 80 100 OFFSET VOLTAGE –
V

0 100 8060 4020 0 20 40 60 80 100 OFFSET VOLTAGE –
V

TPC 1. OP777 Input Offset Voltage Distribution

TPC 2. OP777 Input Offset Voltage Distribution

120 100 80 60

10

0

400

300

200

1.2

0.2 0.4 0.6 0.8 1.0 INPUT OFFSET DRIFT –
V/C

TPC 3. OP777 Input Offset Voltage Drift Distribution

600

VSY = 15V VCM = 0V TA = 25C

500

40

15

0

VSY = 5V VCM = 2.5V TA = 25C

500

NUMBER OF AMPLIFIERS

QUANTITY – Amplifiers

160 140

20

5

600

VSY = 15V VCM = 0V TA = –40C TO +85C

QUANTITY – Amplifiers

200 180

VSY = 15V VCM = 0V TA = 40C TO +85C

25

NUMBER OF AMPLIFIERS

NUMBER OF AMPLIFIERS

200

VSY = 15V VCM = 0V TA = 25C

NUMBER OF AMPLIFIERS

220

400

300

200

100

100

20 0 –120

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 TCVOS –
V/C

TPC 4. OP727/OP747 Input Offset Voltage Drift (TCVOS Distribution)

0
V

600

400

300

200

100 0 140 120 80 40 0 40 80 120 100 140 20 100 60 20 60 OFFSET VOLTAGE –
V

TPC 7. OP727 Input Offset Voltage Distribution

40

80

0 –120

120

–40

0

40

80

120

TPC 6. OP747 Input Offset Voltage Distribution

30

VSY = 15V VCM = 0V TA = 25C

500

–80

OFFSET VOLTAGE –
V

400 300

200

100

VSY = 15V VCM = 0V TA = 25C

25 NUMBER OF AMPLIFIERS

VSY = 5V VCM = 2.5V TA = 25C

NUMBER OF AMPLIFIERS

NUMBER OF AMPLIFIERS

–40

TPC 5. OP747 Input Offset Voltage Distribution

600 500

–80

20

15

10

5

0 0 40 140 120 80 40 80 120 100 140 60 100 60 20 20 OFFSET VOLTAGE –
V

TPC 8. OP727 Input Offset Voltage Distribution

–4–

0 3

5 7 4 6 INPUT BIAS CURRENT – nA

8

TPC 9. Input Bias Current Distribution

REV. B

OP777/OP727/OP747 VS = 5V TA = 25C

1.0

0.1

100 10

SINK

1.0

SOURCE

0 0.001

100

0.1 1 10 LOAD CURRENT – mA

TPC 10. Output Voltage to Supply Rail vs. Load Current

140

ISY+ (VSY = 5V)

100 0 100 200

ISY (VSY = 5V)

300

500 60 40 20 0 20 40 60 80 100 120 140 TEMPERATURE – C

200 150 100

0

TPC 13. Supply Current vs. Temperature

0

5

10 15 20 25 SUPPLY VOLTAGE – V

60

VSY = 5V CLOAD = 0 RLOAD =

80

0

60

45

40

90

20

135

0

180

–20

225

–40

270 1k

10k 100k 1M FREQUENCY – Hz

10M

100M

TPC 16. Open Loop Gain and Phase Shift vs. Frequency

CLOSED-LOOP GAIN – dB

100

0 45

40

90

20

135

0

180

–20

225

–40

270

–60 10

35

30

40

AV = 100

30 20 10

AV = 10

0 10

AV = +1

20 30 40 1k

100

1k

10k 100k

1M

10M 100M

FREQUENCY – Hz

TPC 15. Open Loop Gain and Phase Shift vs. Frequency

60

VSY = 15V CLOAD = 0 RLOAD = 2k

50

PHASE SHIFT – Degrees

120

80 60

TPC 14. Supply Current vs. Supply Voltage

140

OPEN-LOOP GAIN – dB

250

50

ISY (VSY = 15V)

400

100 OPEN-LOOP GAIN – dB

SUPPLY CURRENT –
A

SUPPLY CURRENT –
A

200

VSY = 15V CLOAD = 0 RLOAD =

120

300

ISY+ (VSY = 15V)

2

TPC 12. Input Bias Current vs. Temperature

TA = 25C

300

3

0 60 40 20 0 20 40 60 80 100 120 140 TEMPERATURE – C

100

350

400

REV. B

0.1 1 10 LOAD CURRENT – mA

0.01

TPC 11. Output Voltage to Supply Rail vs. Load Current

500

4

1

0.1

0.01

5

VSY = 5V CLOAD = 0 RLOAD = 2k

50 40

AV = 100

30 20 10

AV = 10

0 10

AV = +1

20 30

10k

100k 1M 10M FREQUENCY – Hz

100M

TPC 17. Closed Loop Gain vs. Frequency

–5–

40 1k

10k

100k 1M 10M FREQUENCY – Hz

100M

TPC 18. Closed Loop Gain vs. Frequency

PHASE SHIFT – Degrees

SOURCE 10

INPUT BIAS CURRENT – nA

SINK

100

–60 100

VSY = 15V

1k OUTPUT VOLTAGE – mV

OUTPUT VOLTAGE – mV

1k

0 0.001

6

10k

VS = 15V TA = 25C

CLOSED-LOOP GAIN – dB

10k

OP777/OP727/OP747 240 210 180 150 120 90 60

AV = 100

AV = 10

240 210

AV = 1

180 150 120 90 60

30

0V

AV = 100 AV = 10

100k 10k 1M FREQUENCY – Hz

10M

0 100

100M

TPC 21. Large Signal Transient Response

VSY = 15V CL = 300pF RL = 2k VIN = 100mV

AV = 1

20 OS

15 10 5

SMALL SIGNAL OVERSHOOT – %

OS

25

TIME – 10
s/DIV

TPC 23. Small Signal Transient Response

35

VSY = 2.5V RL = 2k VIN = 100mV

30

TIME – 100
s/DIV

TIME – 10
s/DIV

TPC 22. Large Signal Transient Response

35

100M

AV = 1

TIME – 100
s/DIV

40

10M

VSY = 2.5V CL = 300pF RL = 2k VIN = 100mV

VOLTAGE – 50mV/DIV

0V

10k 1M 100k FREQUENCY – Hz

TPC 20. Output Impedance vs. Frequency

VSY = 15V RL = 2k CL = 300pF AV = 1

1k

VOLTAGE – 50mV/DIV

1k

TPC 19. Output Impedance vs. Frequency

VOLTAGE – 1V/DIV

AV = 1

30

0 100

SMALL SIGNAL OVERSHOOT – %

VSY = 2.5V RL = 2k CL = 300pF

VSY = 15V

270

AV = 1

OUTPUT IMPEDANCE – 

OUTPUT IMPEDANCE – 

300

VSY = 5V

270

VOLTAGE – 1V/DIV

300

VSY = 15V RL = 2k VIN = 100mV

30

TPC 24. Small Signal Transient Response

INPUT +200mV 0V

25

VSY = 15V RL = 10k AV = 100 VIN = 200mV

+OS 20 OS 15

0V 10

10V

5

OUTPUT 0

1

100 10 CAPACITANCE – pF

1k

TPC 25. Small Signal Overshoot vs. Load Capacitance

0

1

10 100 1k CAPACITANCE – pF

10k

TPC 26. Small Signal Overshoot vs. Load Capacitance

–6–

TIME – 40
s/DIV

TPC 27. Negative Overvoltage Recovery

REV. B

OP777/OP727/OP747 200mV INPUT

INPUT

0V

INPUT

0V

0V

VSY = 15V RL = 10k AV = 100 VIN = 200mV

200mV

10V

VSY = 2.5V RL = 10k AV = 100 VIN = 200mV 0V

OUTPUT

2V

2V

0V

0V

OUTPUT

TIME – 40
s/DIV

OUTPUT

TIME – 40
s/DIV

TPC 29. Negative Overvoltage Recovery

140

VS = 15V AV = 1

VOLTAGE – 5V/DIV

TIME – 40
s/DIV

CMRR – dB

OUTPUT

140

VSY = 2.5V

120

120

100

100

80 60

60 40

20

20

0

10

100

10k 100k 1k FREQUENCY – Hz

1M

0

10M

TPC 32. CMRR vs. Frequency

140

140

120

10

100

10k 100k 1k FREQUENCY – Hz

1M

TPC 33. CMRR vs. Frequency

VSY = 15V

VSY = 2.5V

VSY = 15V

80

40

TIME – 400
s/DIV

TPC 31. No Phase Reversal

TPC 30. Positive Overvoltage Recovery

CMRR – dB

TPC 28. Positive Overvoltage Recovery

INPUT

VSY = 2.5V RL = 10k AV = 100 VIN = 200mV

200mV

VSY = 5V GAIN = 10M

120 +PSRR

80 60

+PSRR 80 PSRR 60

40

40

20

20

0

10

100

10k 100k 1k FREQUENCY – Hz

1M

TPC 34. PSRR vs. Frequency

REV. B

10M

VOLTAGE – 1V/DIV

100 PSRR

PSRR – dB

PSRR – dB

100

0

10

100

10k 100k 1k FREQUENCY – Hz

1M

TPC 35. PSRR vs. Frequency

–7–

10M

TIME – 1s/DIV

TPC 36. 0.1 Hz to 10 Hz Input Voltage Noise

10M

OP777/OP727/OP747 90

90

VSY = 15V

VSY = 2.5V

VOLTAGE NOISE DENSITY – nV/ Hz

VOLTAGE – 1V/DIV

VOLTAGE NOISE DENSITY – nV/ Hz

VSY = 15V GAIN = 10M

80 70 60 50 40 30 20

80 70 60 50 40 30 20

10 0

200 300 FREQUENCY – Hz

400

40

40

30 25 20 15 10 5

500

1k 1.5k FREQUENCY – Hz

2.0k

50

20 15 10 5

ISC

10 0 10 20 ISC+

50 60 40 20 0 20 40 60 80 100 120 140 TEMPERATURE – C

TPC 43. Short Circuit Current vs. Temperature

400

500

VSY = 5V

40 30 20

ISC

10 0 10 20

ISC+

30 40

500

1k 1.5k FREQUENCY – Hz

2.0k

2.5k

TPC 41. Voltage Noise Density

50 60 40 20 0 20 40 60 80 100 120 140 TEMPERATURE – C

TPC 42. Short Circuit Current vs. Temperature

160

4.95 VSY = 5V IL = 1mA

OUTPUT VOLTAGE HIGH – V

30

40

25

0

VSY = 15V

40

30

30

2.5k

TPC 40. Voltage Noise Density

20

35

0

0

200 300 FREQUENCY – Hz

50

VSY = 2.5V SHORT CIRCUIT CURRENT – mA

35

100

TPC 39. Voltage Noise Density

4.94

4.93

4.92

4.91

4.90

150

OUTPUT VOLTAGE LOW – mV

VSY = 15V

0

500

TPC 38. Voltage Noise Density

0

SHORT CIRCUIT CURRENT – mA

10 100

TPC 37. 0.1 Hz to 10 Hz Input Voltage Noise

VOLTAGE NOISE DENSITY – nV/ Hz

VOLTAGE NOISE DENSITY – nV/ Hz

TIME – 1s/DIV

VSY = 5V IL = 1mA

140 130 120 110 100 90 80

4.89 60 40 20 0 20 40 60 80 100 120 140 TEMPERATURE – C

TPC 44. Output Voltage High vs. Temperature

–8–

70 60 40 20 0 20 40 60 80 100 120 140 TEMPERATURE – C

TPC 45. Output Voltage Low vs. Temperature

REV. B

OP777/OP727/OP747 14.960 14.958 14.956 14.954 14.952 14.950 14.948

14.935

1.5

VSY = 15V IL = 1mA

VSY = 15V VCM = 0V TA = 25C

1.0

14.940

0.5

VOS –
V

OUTPUT VOLTAGE HIGH – V

14.962

14.930

VSY = 15V IL = 1mA OUTPUT VOLTAGE LOW – V

14.964

14.945

0

14.950

0.5

14.955

1.0

14.960 60 40 20 0 20 40 60 80 100 120 140 TEMPERATURE – C

1.5

14.946 14.944 60 40 20 0 20 40 60 80 100 120 140 TEMPERATURE – C

TPC 46. Output Voltage High vs. Temperature

0

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 TIME – Minutes

TPC 48. Warm-Up Drift

TPC 47. Output Voltage Low vs. Temperature

BASIC OPERATION

VOLTAGE – 100
V/DIV

The OP777/OP727/OP747 amplifier uses a precision Bipolar PNP input stage coupled with a high-voltage CMOS output stage. This enables this amplifier to feature an input voltage range which includes the negative supply voltage (often groundin single-supply applications) and also swing to within 1 mV of the output rails. Additionally, the input voltage range extends to within 1 V of the positive supply rail. The epitaxial PNP input structure provides high breakdown voltage, high gain, and an input bias current figure comparable to that obtained with a “Darlington” input stage amplifier but without the drawbacks (i.e., severe penalties for input voltage range, offset, drift and noise). The PNP input structure also greatly lowers the noise and reduces the dc input error terms.

0V VIN

TIME – 0.2ms/DIV

Supply Voltage

Figure 1. Input and Output Signals with VCM < 0 V

The amplifiers are fully specified with a single 5 V supply and, due to design and process innovations, can also operate with a supply voltage from 2.7 V up to 30 V. This allows operation from most split supplies used in current industry practice, with the advantage of substantially increased input and output voltage ranges over conventional split-supply amplifiers. The OP777/OP727/OP747 series is specified with (VSY = 5 V, V– = 0 V and VCM = 2.5 V which is most suitable for single supply application. With PSRR of 130 dB (0.3 µV/V) and CMRR of 110 dB (3 µV/V) offset is minimally affected by power supply or common-mode voltages. Dual supply, ±15 V operation is also fully specified.

100k 100k

+3V

0.27V 100k

100k 0.1V

OP777/ OP727/ OP747

VIN = 1kHz at 400mV p-p

Input Common-Mode Voltage Range

Figure 2. OP777/OP727/OP747 Configured as a Difference Amplifier Operating at VCM < 0 V

The OP777/OP727/OP747 is rated with an input common-mode voltage which extends from the minus supply to within 1 V of the positive supply. However, the amplifier can still operate with input voltages slightly below VEE. In Figure 2, OP777/OP727/OP747 is configured as a difference amplifier with a single supply of 2.7 V and negative dc common-mode voltages applied at the inputs terminals. A 400 mV p-p input is then applied to the noninverting input. It can be seen from the graph below that the output does not show any distortion. Micropower operation is maintained by using large input and feedback resistors.

REV. B

VOUT

–9–

OP777/OP727/OP747 Input Over Voltage Protection

30V

OP777/ OP727/ OP747

V p-p = 32V

VOUT

TIME – 400
s/DIV

Figure 4. No Phase Reversal Output Stage

The CMOS output stage has excellent (and fairly symmetric) output drive and with light loads can actually swing to within 1 mV of both supply rails. This is considerably better than similar amplifiers featuring (so-called) rail-to-rail bipolar output stages. OP777/ OP727/OP747 is stable in the voltage follower configuration and responds to signals as low as 1 mV above ground in single supply operation. 2.7V TO 30V

Figure 3a. Unity Gain Follower

VOUT = 1mV

VSY = 15V

VOLTAGE – 5V/DIV

VIN

VSY = 15V

VIN

VOLTAGE – 5V/DIV

When the input of an amplifier is more than a diode drop below VEE, or above VCC, large currents will flow from the substrate (V–) or the positive supply (V+), respectively, to the input pins which can destroy the device. In the case of OP777/OP727/ OP747, differential voltages equal to the supply voltage will not cause any problem (see Figure 3). OP777/OP727/OP747 has built in 500 Ω internal current limiting resistors, in series with the inputs, to minimize the chances of damage. It is a good practice to keep the current flowing into the inputs below 5 mA. In this context it should also be noted that the high breakdown of the input transistors removes the necessity for clamp diodes between the inputs of the amplifier, a feature that is mandatory on many precision op amps. Unfortunately, such clamp diodes greatly interfere with many application circuits such as precision rectifiers and comparators. The OP777/OP727/OP747 series is free from such limitations.

VIN = 1mV

VOUT

OP777/ OP727/ OP747

VOLTAGE – 25mV/DIV

Figure 5. Follower Circuit

TIME – 400
s/DIV

Figure 3b. Input Voltage Can Exceed the Supply Voltage Without Damage

1.0mV

Phase Reversal

Many amplifiers misbehave when one or both of the inputs are forced beyond the input common-mode voltage range. Phase reversal is typified by the transfer function of the amplifier effectively reversing its transfer polarity. In some cases this can cause lockup in servo systems and may cause permanent damage or nonrecoverable parameter shifts to the amplifier. Many amplifiers feature compensation circuitry to combat these effects, but some are only effective for the inverting input. Additionally, many of these schemes only work for a few hundred millivolts or so beyond the supply rails. OP777/ OP727/OP747 has a protection circuit against phase reversal when one or both inputs are forced beyond their input commonmode voltage range. It is not recommended that the parts be continuously driven more than 3 V beyond the rails.

TIME – 10
s/DIV

Figure 6. Rail-to-Rail Operation Output Short Circuit

The output of the OP777/OP727/OP747 series amplifier is protected from damage against accidental shorts to either supply voltage, provided that the maximum die temperature is not exceeded on a long-term basis (see Absolute Maximum Rating section). Current of up to 30 mA does not cause any damage. A Low-Side Current Monitor

In the design of power supply control circuits, a great deal of design effort is focused on ensuring a pass transistor’s long-term reliability over a wide range of load current conditions. As a result, monitoring

–10–

REV. B

OP777/OP727/OP747 and limiting device power dissipation is of prime importance in these designs. Figure 7 shows an example of 5 V, single supply current monitor that can be incorporated into the design of a voltage regulator with foldback current limiting or a high current power supply with crowbar protection. The design capitalizes on the OP777’s common-mode range that extends to ground. Current is monitored in the power supply return where a 0.1 Ω shunt resistor, RSENSE, creates a very small voltage drop. The voltage at the inverting terminal becomes equal to the voltage at the noninverting terminal through the feedback of Q1, which is a 2N2222 or equivalent NPN transistor. This makes the voltage drop across R1 equal to the voltage drop across RSENSE. Therefore, the current through Q1 becomes directly proportional to the current through RSENSE, and the output voltage is given by: VOUT

15V

1k REF 192

2N2222

1/4 OP747 R2

12k 4

3 20k

+15V

R1

R1

R(1+ )

R

+15V

VO

1/4 OP747 15V

R2 V R1 REF R = R

VO =

1/4 OP747 15V

Figure 9. Linear Response Bridge

 R2  = 5V −  × RSENSE × I L   R1 

A single supply current source is shown in Figure 10. Large resistors are used to maintain micropower operation. Output current can be adjusted by changing the R2B resistor. Compliance voltage is:

The voltage drop across R2 increases with IL increasing, so VOUT decreases with higher supply current being sensed. For the element values shown, the VOUT is 2.5 V for return current of 1 A.

VL ≤ VSAT − VS 10pF 2.7V TO 30V

5V

100k

R2 = 2.49k 100k

VOUT

OP777

R1 = 100k

Q1

R2B 2.7k

5V 10pF

OP777

R1 = 100 0.1

IO =

RETURN TO GROUND

RSENSE

IO

R2 = R2A + R2B R2 V R1  R2B S

R2A 97.3k

+ VL

RLOAD 

= 1mA  11mA

Figure 7. A Low-Side Load Current Monitor

Figure 10. Single Supply Current Source

The OP777/OP727/OP747 is very useful in many bridge applications. Figure 8 shows a single supply bridge circuit in which its output is linearly proportional to the fractional deviation () of the bridge. Note that  = ∆R/R.

A single supply instrumentation amplifier using one OP727 amplifier is shown in Figure 11. For true difference R3/R4 = R1/R2. The formula for the CMRR of the circuit at dc is CMRR = 20 × log (100/(1–(R2 × R3)/(R1× R4)). It is common to specify the accuracy of the resistor network in terms of resistor-to-resistor percentage mismatch. We can rewrite the CMRR equation to reflect this CMRR = 20 × log (10000/% Mismatch). The key to high CMRR is a network of resistors that are well matched from the perspective of both resistive ratio and relative drift. It should be noted that the absolute value of the resistors and their absolute drift are of no consequence. Matching is the key. CMRR is 100 dB with 0.1% mismatched resistor network. To maximize CMRR, one of the resistors such as R4 should be trimmed. Tighter matching of two op amps in one package (OP727) offers a significant boost in performance over the triple op amp configuration.

= 300 AR1VREF

15V

VO =

2R2 R1 = R1 RG = 10k

2

1/4 OP747

6

REF 192

2

1M

2.5V 4 REF 192 4

+ 2.5V

10.1k

3

1M

0.1
F 15V 15V

3

R1

R1(1+ ) V1

10.1k VO

1/4 OP747 R1(1+ )

1/4 OP747

R1

R3 = 10.1k

R2 = 1M

R2 2.7V TO 30V

V2

2.7V TO 30V

R4 = 1M R1 = 10.1k

Figure 8. Linear Response Bridge, Single Supply

VO

1/2 OP727

In systems where dual supplies are available, the circuit of Figure 9 could be used to detect bridge outputs that are linearly related to the fractional deviation of the bridge.

1/2 OP727

V1 V2

VO = 100 (V2  V1) 0.02mV V1  V2 2mV VOUT 29V

290mV

USE MATCHED RESISTORS

Figure 11. Single Supply Micropower Instrumentation Amplifier

REV. B

–11–

OP777/OP727/OP747 OUTLINE DIMENSIONS Dimensions shown in inches and (mm).

14-Lead SOIC (R-14) 0.3444 (8.75) 0.3367 (8.55)

0.122 (3.10) 0.114 (2.90)

8

0.1574 (4.00) 0.1497 (3.80)

5

0.122 (3.10) 0.114 (2.90)

0.199 (5.05) 0.187 (4.75) 1

14

8

1

7

0.050 (1.27) BSC

0.0688 (1.75) 0.0532 (1.35)

4

PIN 1

PIN 1 0.0256 (0.65) BSC 0.120 (3.05) 0.112 (2.84)

0.120 (3.05) 0.112 (2.84) 0.043 (1.09) 0.037 (0.94)

0.006 (0.15) 0.002 (0.05) 0.018 (0.46) SEATING 0.008 (0.20) PLANE

0.011 (0.28) 0.003 (0.08)

33 27

0.0098 (0.25) 0.0040 (0.10)

0.028 (0.71) 0.016 (0.41)

14-Lead TSSOP (RU-14) 0.201 (5.10) 0.193 (4.90)

0.1968 (5.00) 0.1890 (4.80) 8

5

1

4

14

0.2440 (6.20) 0.2284 (5.80)

8

0.177 (4.50) 0.169 (4.30) 0.256 (6.50) 0.246 (6.25)

PIN 1 0.0196 (0.50)  45 0.0099 (0.25)

SEATING PLANE

1

0.0688 (1.75) 0.0532 (1.35) 0.0192 (0.49) 0.0138 (0.35)

7

PIN 1 0.006 (0.15) 0.002 (0.05)

8 0.0500 (1.27) 0.0098 (0.25) 0 0.0160 (0.41) 0.0075 (0.19)

SEATING PLANE

0.0433 (1.10) MAX

0.0256 (0.65) BSC

0.0118 (0.30) 0.0075 (0.19)

0.0079 (0.20) 0.0035 (0.090)

8 0

0.028 (0.70) 0.020 (0.50)

8-Lead TSSOP (RU-8) 0.122 (3.10) 0.114 (2.90)

8

PRINTED IN U.S.A.

0.0500 (1.27) BSC 0.0098 (0.25) 0.0040 (0.10)

0.0196 (0.50)  45 0.0099 (0.25)

8 0.0192 (0.49) SEATING 0.0099 (0.25) 0 0.0500 (1.27) PLANE 0.0138 (0.35) 0.0160 (0.41) 0.0075 (0.19)

8-Lead SOIC (R-8)

0.1574 (4.00) 0.1497 (3.80)

0.2440 (6.20) 0.2284 (5.80)

C02051–0–1/01 (rev. B)

8-Lead MSOP (RM-8)

5

0.177 (4.50) 0.169 (4.30) 0.256 (6.50) 0.246 (6.25) 1

4

PIN 1 0.0256 (0.65) BSC 0.006 (0.15) 0.002 (0.05) SEATING PLANE

0.0118 (0.30) 0.0075 (0.19)

0.0433 (1.10) MAX 0.0079 (0.20) 0.0035 (0.090)

–12–

8 0

0.028 (0.70) 0.020 (0.50)

REV. B