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a
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 APPLICATIONS Current Sensing (Shunt) Line or Battery-Powered Instrumentation Remote Sensors Precision Filters OP727 SOIC Pin-Compatible with LT1013 GENERAL DESCRIPTION
Precision Micropower Single-Supply Operational Amplifiers OP777/OP727/OP747
FUNCTIONAL BLOCK DIAGRAMS 8-Lead MSOP (RM-8)
NC IN IN V 1 8 NC V+ OUT NC
14-Lead SOIC (R-14)
OUT A 1 -IN A 2 IN A 3 V
4
OP777
4 5 NC = NO CONNECT
14 13 12
OUT D -IN D IN D V- IN C -IN C OUT C
OP747
8-Lead SOIC (R-8)
TOP VIEW (Not to Scale) 10 IN B 5 -IN B 6 OUT B 7
9 8
11
NC 1 IN 2 +IN 3 V 4
OP777
8 NC 7 V+ 6 OUT 5 NC
OUT A 1 -IN A 2
14 13 12
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 amplifier s 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 A per amplifier at 5 V. 500 series resistors protect the inputs, allowing input signal levels several volts above the positive supply without phase reversal. 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 (-40C to +85C) temperature range. The OP777, single, is available in 8-lead MSOP and 8-lead SOIC packages. 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. The OP727, dual, is available in 8-lead TSSOP and 8-lead SOIC packages. The OP727 8-lead SOIC pin configuration differs from the standard 8-lead operational amplifier pinout.
14-Lead TSSOP (RU-14)
OUT D -IN D IN D
NC = NO CONNECT
8-Lead TSSOP (RU-8)
OUT A 1 -IN A 2
8
IN A 3 V
4
TOP VIEW 11 V- (Not to Scale) 10 IN B 5 IN C -IN B 6
9 8
OP747
-IN C OUT C
V
OUT B
7
7 OUT B OP727 TOP VIEW IN A 3 (Not to Scale) 6 -IN B
V- 4
5
IN B
8-Lead SOIC (R-8)
IN A 1 V- 2
8
-IN A
OUT A TOP VIEW IN B 3 (Not to Scale) 6 V
7
OP727
-IN B 4
5
OUT B
NOTE: THIS PIN CONFIGURATION DIFFERS FROM THE STANDARD 8-LEAD OPERATIONAL AMPLIFIER PINOUT.
REV. C
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. 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 www.analog.com Fax: 781/326-8703 (c) Analog Devices, Inc., 2001
OP777/OP727/OP747-SPECIFICATIONS
ELECTRICAL CHARACTERISTICS (@ V = 5.0 V, V
S CM
= 2.5 V, TA = 25 C unless otherwise noted.)
Min Typ 20 50 30 60 5.5 0.1 0 104 300 110 500 0.3 0.4 4.91 126 10 130 220 270 235 290 0.2 0.7 0.4 15 0.13 Max 100 200 160 300 11 2 4 Unit V V V V nA nA V dB V/mV V/C V/C V mV mA dB A A A A V/s MHz V p-p nV/Hz pA/Hz
Parameter INPUT CHARACTERISTICS Offset Voltage OP777 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 OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Output Circuit POWER SUPPLY Power Supply Rejection Ratio Supply Current/Amplifier OP777 Supply Current/Amplifier OP727/OP747 DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product NOISE PERFORMANCE Voltage Noise Voltage Noise Density Current Noise Density
Symbol VOS
Conditions +25 C < T A < +85 C -40C < T A < +85 C +25 C < T A < +85 C -40C < T A < +85 C -40C < T A < +85 C -40C < T A < +85 C VCM = 0 V to 4 V RL = 10 k , VO = 0.5 V to 4.5 V -40C < T A < +85 C -40C < T A < +85 C IL = 1 mA, -40 C to +85 C IL = 1 mA, -40 C to +85 C VDROPOUT < 1 V VS = 3 V to 30 V VO = 0 V -40C < T A < +85 C VO = 0 V -40C < T A < +85 C RL = 2 k
IB IOS CMRR AVO VOS/T VOS/T VOH VOL IOUT PSRR ISY
1.3 1.5
4.88
140
120
270 320 290 350
SR GBP enp-p en in
0.1 Hz to 10 Hz f = 1 kHz f = 1 kHz
NOTES Typical specifications: >50% of units perform equal to or better than the "typical" value. Specifications subject to change without notice.
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REV. C
OP777/OP727/OP747 ELECTRICAL CHARACTERISTICS (@
Parameter INPUT CHARACTERISTICS Offset Voltage OP777 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 OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Output Circuit POWER SUPPLY Power Supply Rejection Ratio Supply Current/Amplifier OP777 Supply Current/Amplifier OP727/747 DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product NOISE PERFORMANCE Voltage Noise Voltage Noise Density Current Noise Density
Specifications subject to change without notice.
15 V, VCM = 0 V, TA = 25 C unless otherwise noted.)
Conditions +25 C < T A < +85 C -40C < T A < +85 C +25 C < T A < +85 C -40C < T A < +85 C -40C < T A < +85 C -40C < T A < +85 C VCM = -15 V to +14 V RL = 10 k , V O = -14.5 V to +14.5 V -40C < T A < +85 C -40C < T A < +85 C IL = 1 mA, -40 C to +85 C IL = 1 mA, -40 C to +85 C -15 110 1,000 Min Typ 30 50 30 50 5 0.1 120 2,500 0.3 0.4 Max 100 200 160 300 10 2 +14 Unit V V V V nA nA V dB V/mV V/C V/C V V mA dB A A A A V/s MHz V p-p nV/Hz pA/Hz
Symbol VOS VOS IB IOS CMRR AVO VOS/T VOS/T VOH VOL IOUT PSRR ISY
1.3 1.5
+14.9
+14.94 -14.94 -14.9 30 130 300 350 320 375 0.2 0.7 0.4 15 0.13
VS = 1.5 V to 15 V VO = 0 V -40C < T A < +85 C VO = 0 V -40C < T A < +85 C RL = 2 k
120
350 400 375 450
SR GBP enp-p en in
0.1 Hz to 10 Hz f = 1 kHz f = 1 kHz
REV. C
-3-
OP777/OP727/OP747
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 . . . . . . . . . . . . . . . . -65C to +150C Operating Temperature Range OP777/OP727/OP747 . . . . . . . . . . . . . . . -40C to +85C Junction Temperature Range RM, R, RU Packages . . . . . . . . . . . . . . . . -65C to +150C Lead Temperature Range (Soldering, 60 sec) . . . . . . . 300C Electrostatic Discharge (Human Body Model) . . . . 2000 V max
Package Type 8-Lead MSOP (RM) 8-Lead SOIC (R) 8-Lead TSSOP (RU) 14-Lead SOIC (R) 14-Lead TSSOP (RU)
3 JA
JC
Unit C/W C/W C/W C/W C/W
190 158 240 120 180
44 43 43 36 35
NOTES 1 Absolute maximum ratings apply at 25C, 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 JA is specified for worst-case conditions, i.e., JA is specified for device soldered in circuit board for surface-mount packages.
ORDERING GUIDE
Model OP777ARM OP777AR OP727ARU OP727AR OP747AR OP747ARU
Temperature Range -40C to +85 C -40C to +85 C -40C to +85 C -40C to +85 C -40C to +85 C -40C to +85 C
Package Description 8-Lead MSOP 8-Lead SOIC 8-Lead TSSOP 8-Lead SOIC 14-Lead SOIC 14-Lead TSSOP
Package Option RM-8 SO-8 RU-8 SO-8 R-14 RU-14
Branding Information 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.
WARNING!
ESD SENSITIVE DEVICE
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REV. C
Typical Performance Characteristics- OP777/OP727/OP747
220 200 VSY = 15V VCM = 0V TA = 25 C 220 200 NUMBER OF AMPLIFIERS 180 160 140 120 100 80 60 40 20 0 100 80 60 40 20 0 20 40 60 80 100 OFFSET VOLTAGE - V
0 0 0.2 0.4 0.6 0.8 1.0 INPUT OFFSET DRIFT - V/ C 1.2 30
NUMBER OF AMPLIFIERS
160 140 120 100 80 60 40 20 0 100 80 60 40 20 0 20 40 60 80 100 OFFSET VOLTAGE - V
NUMBER OF AMPLIFIERS
180
VSY = 5V VCM = 2.5V TA = 25 C
25
VSY = 15V VCM = 0V TA = 40 C TO +85 C
20
15
10
5
TPC 1. OP777 Input Offset Voltage Distribution
TPC 2. OP777 Input Offset Voltage Distribution
TPC 3. OP777 Input Offset Voltage Drift Distribution
200 180 160 VSY = 15V VCM = 0V TA = -40 C TO +85 C
600 VSY = 15V VCM = 0V TA = 25 C
600 VSY = 5V VCM = 2.5V TA = 25 C
500
500 NUMBER OF AMPLIFIERS
QUANTITY - Amplifiers
140 120 100 80 60 40 20 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
QUANTITY - Amplifiers
400
400
300
300
200
200
100 0 -120
100 0 -120
-80
-40
0 V
40
80
120
-80
-40
0
40 V
80
120
OFFSET VOLTAGE -
TPC 4. OP727/OP747 Input Offset Voltage Drift (TCVOS Distribution)
TPC 5. OP747 Input Offset Voltage Distribution
TPC 6. OP747 Input Offset Voltage Distribution
600 500 VSY = 5V VCM = 2.5V TA = 25 C
600 VSY = 15V VCM = 0V TA = 25 C
30 VSY = 15V VCM = 0V TA = 25 C
500
25 NUMBER OF AMPLIFIERS
NUMBER OF AMPLIFIERS
NUMBER OF AMPLIFIERS
400
400 300
20
300
15
200
200
10
100 0 140 120
100 0 140 120
5
0 40 40 80 OFFSET VOLTAGE -
80 V
120
0 40 80 40 OFFSET VOLTAGE -
80 V
120
0 3 5 7 4 6 INPUT BIAS CURRENT - nA 8
TPC 7. OP727 Input Offset Voltage Distribution
TPC 8. OP727 Input Offset Voltage Distribution
TPC 9. Input Bias Current Distribution
REV. C
-5-
OP777/OP727/OP747
10k VS = 15V TA = 25 C 1k
10k VS = 5V TA = 25 C INPUT BIAS CURRENT - nA 1k
SINK SOURCE
OUTPUT VOLTAGE - mV
6 VSY = 5 15V
OUTPUT VOLTAGE - mV
100 10
100 10
4
SINK
3 2
1.0
1.0
SOURCE
0.1 0 0.001
0.1 0 0.001
1 0 60 40 20 0 20 40 60 80 100 120 140 TEMPERATURE - C
0.01
0.1 1 10 LOAD CURRENT - mA
100
0.01
0.1 1 10 LOAD CURRENT - mA
100
TPC 10. Output Voltage to Supply Rail vs. Load Current
TPC 11. Output Voltage to Supply Rail vs. Load Current
TPC 12. Input Bias Current vs. Temperature
500 400
350 TA = 25 C 300
140 120 100
OPEN-LOOP GAIN - dB
A
SUPPLY CURRENT - A
300 200 100 0 100 200 300 400 500 60 40
SUPPLY CURRENT -
250 200 150 100 50 0
80 60 40 20 0 -20 -40
0 45 90 135 180 225 270 100 1k 10k 100k 1M 10M 100M
ISY+ (VSY = 5V)
ISY (VSY = 5V)
ISY (VSY =
15V)
20 0 20 40 60 80 100 120 140 TEMPERATURE - C
0
5
10 15 20 25 SUPPLY VOLTAGE - V
30
35
-60 10
FREQUENCY - Hz
TPC 13. Supply Current vs. Temperature
TPC 14. Supply Current vs. Supply Voltage
TPC 15. Open Loop Gain and Phase Shift vs. Frequency
140 120 100
OPEN-LOOP GAIN - dB
60
CLOSED-LOOP GAIN - dB
VSY = 5V CLOAD = 0 RLOAD =
PHASE SHIFT - Degrees
50 40 AV = 30 20 10 0 AV = +1 10 20 30 40 1k 10k AV = 10 100
VSY = 15V CLOAD = 0 RLOAD = 2k
CLOSED-LOOP GAIN - dB
60 50 40 AV = 30 20 10 0 AV = +1 10 20 30 AV = 10 100
VSY = 5V CLOAD = 0 RLOAD = 2k
80 60 40 20 0 -20 -40 -60 100 1k 10k 100k 1M FREQUENCY - Hz 10M
0 45 90 135 180 225 270 100M
100k 1M 10M FREQUENCY - Hz
100M
40 1k
10k
100k 1M 10M FREQUENCY - Hz
100M
TPC 16. Open Loop Gain and Phase Shift vs. Frequency
TPC 17. Closed Loop Gain vs. Frequency
TPC 18. Closed Loop Gain vs. Frequency
-6-
REV. C
PHASE SHIFT - Degrees
ISY+ (VSY =
15V)
VSY = 15V CLOAD = 0 RLOAD =
OP777/OP727/OP747
300 270 240 AV = 1 VSY = 5V 300 270 240 VSY = 15V
VSY = 2.5V RL = 2k CL = 300pF
VOLTAGE - 1V/DIV
OUTPUT IMPEDANCE -
210 180 150 120 90 60 30 0 100 1k 100k 10k 1M FREQUENCY - Hz 10M 100M AV = 10 AV = 100
OUTPUT IMPEDANCE -
210 180 150 120 90 60 30 0 100 1k AV = 100 AV = 10
AV = 1
AV = 1 0V
10k 1M 100k FREQUENCY - Hz
10M
100M
TIME - 100 s/DIV
TPC 19. Output Impedance vs. Frequency
TPC 20. Output Impedance vs. Frequency
TPC 21. Large Signal Transient Response
VSY = 15V RL = 2k CL = 300pF
VOLTAGE - 50mV/DIV
AV = 1
AV = 1
VOLTAGE - 50mV/DIV
VOLTAGE - 1V/DIV
VSY = 2.5V CL = 300pF RL = 2k VIN = 100mV
VSY = 15V CL = 300pF RL = 2k VIN = 100mV
AV = 1
0V
TIME - 100 s/DIV
TIME - 10 s/DIV
TIME - 10 s/DIV
TPC 22. Large Signal Transient Response
TPC 23. Small Signal Transient Response
TPC 24. Small Signal Transient Response
40
35
SMALL SIGNAL OVERSHOOT - %
SMALL SIGNAL OVERSHOOT - %
35 30
VSY = 2.5V RL = 2k VIN = 100mV OS
30 25
VSY = 15V RL = 2k VIN = 100mV
INPUT +200mV 0V
+OS
25 20 OS 15 10 5 0 1 100 10 CAPACITANCE - pF 1k
20 OS 15
VSY = 15V RL = 10k AV = 100 VIN = 200mV 0V
10 5
10V
OUTPUT
0 1 10 100 1k CAPACITANCE - pF 10k
TIME - 40 s/DIV
TPC 25. Small Signal Overshoot vs. Load Capacitance
TPC 26. Small Signal Overshoot vs. Load Capacitance
TPC 27. Negative Overvoltage Recovery
REV. C
-7-
OP777/OP727/OP747
200mV
INPUT 0V 200mV VSY = 15V RL = 10k AV = 100 VIN = 200mV OUTPUT
INPUT 0V VSY = 2.5V RL = 10k AV = 100 VIN = 200mV 0V 2V OUTPUT
0V 200mV
INPUT VSY = 2.5V RL = 10k AV = 100 VIN = 200mV
10V 0V
2V 0V OUTPUT
TIME - 40 s/DIV
TIME - 40 s/DIV
TIME - 40 s/DIV
TPC 28. Positive Overvoltage Recovery
TPC 29. Negative Overvoltage Recovery
TPC 30. Positive Overvoltage Recovery
140 INPUT VS = 15V AV = 1 VSY = 120 100
CMRR - dB CMRR - dB
140
2.5V
120 100 80 60 40 20 0
VSY =
15V
VOLTAGE - 5V/DIV
OUTPUT
80 60 40 20 0
TIME - 400 s/DIV
10
100
10k 100k 1k FREQUENCY - Hz
1M
10M
10
100
10k 100k 1k FREQUENCY - Hz
1M
10M
TPC 31. No Phase Reversal
TPC 32. CMRR vs. Frequency
TPC 33. CMRR vs. Frequency
140 VSY = 120 +PSRR PSRR 80 60 40 20 0 100 2.5V
140 VSY = 120 15V
VSY = 5V GAIN = 10M
PSRR - dB
PSRR - dB
+PSRR 80 PSRR 60 40 20 0
10
100
10k 100k 1k FREQUENCY - Hz
1M
10M
10
100
10k 100k 1k FREQUENCY - Hz
1M
10M
VOLTAGE - 1V/DIV
100
TIME - 1s/DIV
TPC 34. PSRR vs. Frequency
TPC 35. PSRR vs. Frequency
TPC 36. 0.1 Hz to 10 Hz Input Voltage Noise
-8-
REV. C
OP777/OP727/OP747
90
90
VOLTAGE NOISE DENSITY - nV/ Hz
VSY = 15V
VOLTAGE NOISE DENSITY - nV/ Hz
VSY = 15V GAIN = 10M
VSY = 80 70 60 50 40 30 20 10
2.5V
80 70 60 50 40 30 20 10
VOLTAGE - 1V/DIV
TIME - 1s/DIV
0
100
200 300 FREQUENCY - Hz
400
500
0
100
200 300 FREQUENCY - Hz
400
500
TPC 37. 0.1 Hz to 10 Hz Input Voltage Noise
TPC 38. Voltage Noise Density
TPC 39. Voltage Noise Density
40
VOLTAGE NOISE DENSITY - nV/ Hz
VOLTAGE NOISE DENSITY - nV/ Hz
40
50
VSY = 35 30 25 20 15 10 5 0
15V
VSY = 35 30 25 20 15 10 5 0
2.5V
SHORT CIRCUIT CURRENT - mA
40 30 20 10 0 10 20 30 40 50
VSY = 5V
ISC
ISC+
0
500
1k 1.5k FREQUENCY - Hz
2.0k
2.5k
0
500
1k 1.5k FREQUENCY - Hz
2.0k
2.5k
60 40
20 0 20 40 60 80 100 120 140 TEMPERATURE - C
TPC 40. Voltage Noise Density
TPC 41. Voltage Noise Density
TPC 42. Short Circuit Current vs. Temperature
50
4.95 VSY = 15V
160 VSY = 5V IL = 1mA 150 VSY = 5V IL = 1mA
SHORT CIRCUIT CURRENT - mA
40 30 20 10 0 10 20 30 40 50 60 40 ISC+ ISC
OUTPUT VOLTAGE HIGH - V
4.94
OUTPUT VOLTAGE LOW - mV
140 130 120 110 100 90 80
4.93
4.92
4.91
4.90
20 0 20 40 60 80 100 120 140 TEMPERATURE - C
4.89
70 60 40 20 0 20 40 60 80 100 120 140 TEMPERATURE - C 60
40
20 0 20 40 60 80 100 120 140 TEMPERATURE - C
TPC 43. Short Circuit Current vs. Temperature
TPC 44. Output Voltage High vs. Temperature
TPC 45. Output Voltage Low vs. Temperature
REV. C
-9-
OP777/OP727/OP747
14.964 14.962
OUTPUT VOLTAGE HIGH - V
14.930
1.5
VSY = 15V IL = 1mA
OUTPUT VOLTAGE LOW - V
VSY = 15V IL = 1mA 14.935
14.960 14.958 14.956 14.954 14.952 14.950 14.948 14.946 14.944 60 40 20 0 20 40 60 80 100 120 140 TEMPERATURE - C
1.0
VSY = 15V VCM = 0V TA = 25 C
14.940
VOS - V
0.5
14.945
0
14.950 14.955 14.960
0.5
1.0
60
40
20 0 20 40 60 80 100 120 140 TEMPERATURE - C
1.5
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 TIME - Minutes
TPC 46. Output Voltage High vs. Temperature
TPC 47. Output Voltage Low vs. Temperature
TPC 48. Warm-Up Drift
BASIC OPERATION
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.
Supply Voltage
VOLTAGE - 100 V/DIV
VOUT
0V VIN
TIME - 0.2ms/DIV
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 V/V) and CMRR of 110 dB (3 V/V) offset is minimally affected by power supply or common-mode voltages. Dual supply, 15 V operation is also fully specified.
Input Common-Mode Voltage Range
Figure 1. Input and Output Signals with VCM < 0 V
100k 100k 0.27V 100k +3V
100k 0.1V
OP777/ OP727/ OP747
VIN = 1kHz at 400mV p-p
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.
Figure 2. OP777/OP727/OP747 Configured as a Difference Amplifier Operating at VCM < 0 V
-10-
REV. C
OP777/OP727/OP747
Input Over Voltage Protection
When the input of an amplifier is more than a diode drop below VEE, or above V CC, 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 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.
30V
VIN
VSY =
15V
VOLTAGE - 5V/DIV
VOUT
TIME - 400 s/DIV
Figure 4. No Phase Reversal
Output Stage
V p-p = 32V
OP777/ OP727/ OP747
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
VSY = 15V
VOUT = 1mV
VIN
VIN = 1mV
OP777/ OP727/ OP747
VOLTAGE - 5V/DIV
VOUT
Figure 5. Follower Circuit
TIME - 400 s/DIV
VOLTAGE - 25mV/DIV
Figure 3b. Input Voltage Can Exceed the Supply Voltage Without Damage
Phase Reversal
1.0mV
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
REV. C
-11-
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 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 R2 = 5V - x RSENSE x I L R1
15V 1k REF 192 4 3 20k R1 R1 +15V 2N2222
1/4 OP747
12k R2
+15V
R(1+ )
R 15V
VO
1/4 OP747
VO = R2 V R1 REF R = R
1/4 OP747
15V
Figure 9. Linear Response Bridge
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.
5V R2 = 2.49k VOUT Q1 5V
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:
VL VSAT - VS
10pF 2.7V TO 30V 100k 100k R1 = 100k R2B 2.7k 10pF IO R2A 97.3k + VL RLOAD
OP777
R1 = 100 0.1 RSENSE
OP777
RETURN TO GROUND
R2 = R2A + R2B IO = R2 V R1 R2B S 11mA
= 1mA
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.
15V 2 = 300 AR1 VREF 2R2 R1 = R1
VO =
+ 2.5V
1/4 OP747
2 2.5V 4 REF 192 4 3 0.1 F 3 REF 192
6 1M
RG = 10k 10.1k
1M 15V 15V
R1
R1(1+ ) V1 R1
10.1k
1/4 OP747
R1(1+ ) R2
VO
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 x log (100/(1-(R2 x R3)/(R1x R4)). It is common to specify t he accuracy of the resistor network in terms of resistor-to-resistor percentage mismatch. We can rewrite the CMRR equation to reflect this CMRR = 20 x 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.
R3 = 10.1k 2.7V TO 30V R2 = 1M
1/4 OP747
V2
R4 = 1M R1 = 10.1k
2.7V TO 30V
Figure 8. Linear Response Bridge, Single Supply
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
VO
1/2 OP727
USE MATCHED RESISTORS
Figure 11. Single-Supply Micropower Instrumentation Amplifier
-12-
REV. C
OP777/OP727/OP747
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
8-Lead MSOP (RM-8)
0.122 (3.10) 0.114 (2.90)
8
5
0.122 (3.10) 0.114 (2.90)
1 4
0.199 (5.05) 0.187 (4.75)
PIN 1 0.0256 (0.65) BSC 0.120 (3.05) 0.112 (2.84) 0.006 (0.15) 0.002 (0.05) 0.018 (0.46) SEATING 0.008 (0.20) PLANE 0.043 (1.09) 0.037 (0.94) 0.011 (0.28) 0.003 (0.08) 0.120 (3.05) 0.112 (2.84) 33 27
0.028 (0.71) 0.016 (0.41)
8-Lead SOIC (R-8)
0.1968 (5.00) 0.1890 (4.80)
8 5 4
0.1574 (4.00) 0.1497 (3.80) PIN 1
1
0.2440 (6.20) 0.2284 (5.80)
0.0500 (1.27) BSC 0.0098 (0.25) 0.0040 (0.10) SEATING PLANE 0.0688 (1.75) 0.0532 (1.35) 0.0192 (0.49) 0.0138 (0.35) 8 0.0098 (0.25) 0 0.0075 (0.19)
0.0196 (0.50) 0.0099 (0.25)
45
0.0500 (1.27) 0.0160 (0.41)
8-Lead TSSOP (RU-8)
0.122 (3.10) 0.114 (2.90)
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)
8 0
0.028 (0.70) 0.020 (0.50)
REV. C
-13-
OP777/OP727/OP747
14-Lead SOIC (R-14)
0.3444 (8.75) 0.3367 (8.55) 0.1574 (4.00) 0.1497 (3.80)
14 1 8 7
0.2440 (6.20) 0.2284 (5.80)
PIN 1
0.050 (1.27) BSC
0.0688 (1.75) 0.0532 (1.35)
0.0196 (0.50) 0.0099 (0.25)
45
0.0098 (0.25) 0.0040 (0.10)
8 0 0.0192 (0.49) SEATING 0.0099 (0.25) PLANE 0.0138 (0.35) 0.0075 (0.19)
0.0500 (1.27) 0.0160 (0.41)
14-Lead TSSOP (RU-14)
0.201 (5.10) 0.193 (4.90)
14
8
0.177 (4.50) 0.169 (4.30) 0.256 (6.50) 0.246 (6.25)
1 7
PIN 1 0.006 (0.15) 0.002 (0.05) 0.0433 (1.10) MAX
SEATING PLANE
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)
-14-
REV. C
OP777/OP727/OP747 Revision History
Location Data Sheet changed from REV. B to REV. C. Page
Addition of text to APPLICATIONS section Addition of 8-Lead SOIC (R-8) package
............................................................... .............................................................
1 1 1 2
.................................................................. ...............................................................
Addition of text to GENERAL DESCRIPTION Addition of package to ORDERING GUIDE
REV. C
-15-
-16-
CO2051-0-9/01(C)
PRINTED IN U.S.A.

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