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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: 270 A/Amp Unity Gain Stable No Phase Reversal APPLICATIONS Precision Current Measurement Line or Battery-Powered Instrumentation Remote Sensors Precision Filters
Precision Micropower Single Supply Operational Amplifier OP777
FUNCTIONAL BLOCK DIAGRAMS 8-Lead MSOP (RM Suffix)
NC IN IN V 1 8 NC V+ OUT NC
OP777
4 5 NC = NO CONNECT
8-Lead SOIC (R Suffix)
NC 1 IN 2 +IN 3 V 4 8 NC
OP777
7 V+ 6 OUT 5 NC
NC = NO CONNECT
GENERAL DESCRIPTION
The OP777 is a precision single supply amplifier featuring micropower operation and rail-to-rail output ranges. This amplifier provides improved performance over the industry-standard OP07 with 15 V supplies and offers the further advantage of true single supply operation down to 2.7 V, and smaller package footprint than any other high-voltage precision bipolar amplifier. Outputs are stable with capacitive loads of over 1000 pF. Supply current is less than 300 A per amplifier at 5 V. 500 series resistors protect the inputs, allowing input signal levels to exceed either power supply rail by up to 3 V without causing phase reversal of the output signal or causing damage to the amplifier. The proprietary fabrication process yields a very low-voltage noise corner frequency under 10 Hz, greatly improving the low-frequency noise performance of the OP07 and similar amplifiers. The specially fabricated input PNP transistors operate with very low input bias currents while allowing operation with large differential voltages, eliminating a common limitation of many precision amplifiers and enabling application of the OP777 in precision comparator and rectifier circuits. This large differential voltage capability also further reduces the need for external protection devices such as clamping diodes.
Applications for these amplifiers include both line powered and portable instrumentation, remote sensor signal conditioning, and precision filters. The OP777 is specified over the extended industrial (-40C to +85C) temperature range and is available in 8-lead MSOP and 8-lead SOIC packages. The OP777 uses a standard operational amplifier pinout, allowing for easy drop-in replacement of lower performance amplifiers in most circuits. Surface mount devices in MSOP packages are available in tape and reel only.
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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 (c) Analog Devices, Inc., 2000
OP777-SPECIFICATIONS
ELECTRICAL CHARACTERISTICS (V = 5.0 V, V
S CM
= 2.5 V, TA = 25 C unless otherwise noted)
Min Typ Max 100 200 11 2 4 110 500 0.3 Unit V V nA nA V dB V/mV V/C V mV mA dB A A V/s MHz Vp-p nV/Hz pA/Hz
Parameter INPUT CHARACTERISTICS Offset Voltage Input Bias Current Input Offset Current Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Offset Voltage Drift OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Short Circuit Limit POWER SUPPLY Power Supply Rejection Ratio Supply Current/Amplifier DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product NOISE PERFORMANCE Voltage Noise Voltage Noise Density Current Noise Density
Specifications subject to change without notice.
Symbol VOS IB IOS CMRR AVO VOS /T VOH VOL IOUT PSRR ISY
Conditions
-40C TA +85C -40C TA +85C -40C TA +85C VCM = 0 V to 4 V RL = 10 k , VO = 0.5 V to 4.5 V -40C TA +85C IL = 1 mA, -40C TA +85C IL = 1 mA, -40C TA +85C VDROPOUT < 1 V VS = 3 V to 30 V VO = 0 V -40C TA +85C RL = 2 k 0 104 300
1.3
4.88 140 10 120 130 270 0.2 0.7 0.4 15 0.13 270 320
SR GBP enp-p en in
0.1 Hz to 10 Hz f = 1 kHz f = 1 kHz
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OP777 ELECTRICAL CHARACTERISTICS (V =
S
15.0 V, VCM = 0 V, TA = 25 C unless otherwise noted)
Conditions Min Typ Max 100 200 10 2 +14 120 2,500 0.3 1.3 Unit V V nA nA V dB V/mV V/C V V mA dB A A V/s MHz Vp-p nV/Hz pA/Hz
Parameter INPUT CHARACTERISTICS Offset Voltage Input Bias Current Input Offset Current Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Offset Voltage Drift OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Short Circuit Limit POWER SUPPLY Power Supply Rejection Ratio Supply Current/Amplifier DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product NOISE PERFORMANCE Voltage Noise Voltage Noise Density Current Noise Density
Specifications subject to change without notice.
Symbol VOS IB IOS CMRR AVO VOS /T VOH VOL IOUT PSRR ISY
-40C TA +85C -40C TA +85C -40C TA +85C VCM = -15 V to +14 V RL = 10 k , VO = -14.5 V to +14.5 V -40C TA +85C IL = 1 mA, -40C TA +85C IL = 1 mA, -40C TA +85C -15 110 1,000
14.9 -14.9 30 120 130 350 0.2 0.7 0.4 15 0.13 350 400
VS = 1.5 V to 15 V VO = 0 V -40C TA +85C RL = 2 k
SR GBP enp-p en in
0.1 Hz to 10 Hz f = 1 kHz f = 1 kHz
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OP777
ABSOLUTE MAXIMUM RATINGS*
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 V Input Voltage . . . . . . . . . . . . . . . . . . . . . VS- - 3 V to VS+ + 3 V Differential Input Voltage . . . . . . . . . . . . . . Supply Voltage Output Short-Circuit Duration to GND . . . . . . . . . Indefinite Storage Temperature Range R, RM Packages . . . . . . . . . . . . . . . . . . . . -65C to +150C Operating Temperature Range OP777 . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40C to +85C Junction Temperature Range R, RM Packages . . . . . . . . . . . . . . . . . . . . -65C to +150C Lead Temperature Range (Soldering, 60 sec) . . . . . . . . 300C ESD (HBM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 kV
*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.
Package Type 8-Lead MSOP (RM) 8-Lead SOIC (R)
JA
1
JC
Unit C/W C/W
190 158
44 43
NOTE 1 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
Temperature Range -40C to +85C -40C to +85C
Package Description 8-Lead MSOP 8-Lead SOIC
Package Option RM-8 SO-8
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 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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Typical Performance Characteristics-OP777
220 200
NUMBER OF AMPLIFIERS
220 VSY = 15V VCM = 0V TA = 25 C 200
NUMBER OF AMPLIFIERS
30
160 140 120 100 80 60 40 20 0 100 80 60 40 20 0 20 40 60 80 100 OFFSET VOLTAGE - V
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
180
VSY = 5V VCM = 2.5V TA = 25 C
25
VSY = 15V VCM = 0V TA = 40 C TO +85 C
20
15
10
5
0 0 0.2 0.4 0.6 0.8 1.0 INPUT OFFSET DRIFT - V/ C 1.2
Figure 1. Input Offset Voltage Distribution
Figure 2. Input Offset Voltage Distribution
Figure 3. Input Offset Voltage Drift Distribution
30 VSY = 15V VCM = 0V TA = 25 C
10k
10k VS = 5V TA = 25 C
OUTPUT VOLTAGE - mV
25 NUMBER OF AMPLIFIERS
1k
1k
VS = 15V TA = 25 C
OUTPUT VOLTAGE - mV
20
100 10
SINK SOURCE
100 10
15
SINK
10
1.0
1.0
SOURCE
5
0.1 0 0.001
0.1 0 0.001
0 3 5 7 4 6 INPUT BIAS CURRENT - nA 8
0.01
0.1 1 10 LOAD CURRENT - mA
100
0.01
0.1 1 10 LOAD CURRENT - mA
100
Figure 4. Input Bias Current Distribution
Figure 5. Output Voltage to Supply Rail vs. Load Current
Figure 6. Output Voltage to Supply Rail vs. Load Current
10 VSY = 5
INPUT BIAS CURRENT - nA
500 15V 400 ISY+ (VSY = 15V)
350 TA = 25 C 300
SUPPLY CURRENT - A
0 5 10 15 20 25 30
SUPPLY CURRENT - A
200 100 0 100 200 ISY (VSY = 5V) 300 400 500 ISY (VSY = 60 40 15V) ISY+ (VSY = 5V)
250 200 150 100 50 0
60 40
20 0 20 40 60 80 100 120 140 TEMPERATURE - C
20 0 20 40 60 80 100 120 140 TEMPERATURE - C
0
5
10 15 20 25 SUPPLY VOLTAGE - V
30
35
Figure 7. Input Bias Current vs. Temperature
Figure 8. Supply Current vs. Temperature
Figure 9. Supply Current vs. Supply Voltage
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OP777
70 60
OPEN-LOOP GAIN - dB
70 VSY = 15V CLOAD = 0 RLOAD = 60
PHASE SHIFT - Degrees OPEN-LOOP GAIN - dB
PHASE SHIFT - Degrees
50 40 30 20 10 0 10 20 30 10 100
CLOSED-LOOP GAIN - dB
0 45 90 135 180 225 270
50 40 30 20 10 0 10 20
VSY = 5V CLOAD = 0 RLOAD =
60 50 0 45 90 135 180 225 270 40 AV = 30 20 10 0 AV = +1 10 20 30 AV = 10 100 VSY = 15V CLOAD = 0 RLOAD = 2k
1k 10k 100k 1M FREQUENCY - Hz
10M 100M
30 100
1k
10k 1M 100k FREQUENCY - Hz
10M
100M
40 1k
10k
100k 1M 10M FREQUENCY - Hz
100M
Figure 10. Open Loop Gain and Phase Shift vs. Frequency
Figure 11. Open Loop Gain and Phase Shift vs. Frequency
Figure 12. Closed Loop Gain vs. Frequency
60 50
300 VSY = 5V CLOAD = 0 RLOAD = 2k
OUTPUT IMPEDANCE -
270 240 210 180 150 120 90 60 30 AV = 10
VSY = 5V AV = 1
OUTPUT IMPEDANCE -
300 270 240 210 180 150 120 90 60 30 AV = 100 AV = 10 AV = 1 VSY = 15V
CLOSED-LOOP GAIN - dB
40 AV = 30 20 10 0 AV = +1 10 20 30 40 1k 10k AV = 10 100
AV = 100
100k 1M 10M FREQUENCY - Hz
100M
0 100
1k
100k 10k 1M FREQUENCY - Hz
10M
100M
0 100
1k
10k 1M 100k FREQUENCY - Hz
10M
100M
Figure 13. Closed Loop Gain vs. Frequency
Figure 14. Output Impedance vs. Frequency
Figure 15. Output Impedance vs. Frequency
VSY = 2.5V RL = 2k CL = 300pF VOLTAGE - 1V/DIV
VOLTAGE - 1V/DIV
VSY = 15V RL = 2k CL = 300pF VOLTAGE - 50mV/DIV
VSY = 2.5V CL = 300pF RL = 2k VIN = 100mV
TIME - 100 s/DIV
TIME - 100 s/DIV
TIME - 10 s/DIV
Figure 16. Large Signal Transient Response
Figure 17. Large Signal Transient Response
Figure 18. Small Signal Transient Response
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OP777
40 35
SMALL SIGNAL OVERSHOOT - %
SMALL SIGNAL OVERSHOOT - %
VOLTAGE - 50mV/DIV
VSY = 15V CL = 300pF RL = 2k VIN = 100mV
35 30 25 20 15 10 5 0 1
VSY = 2.5V RL = 2k VIN = 100mV
30 25
VSY = 15V RL = 2k VIN = 100mV
+OS 20 OS 15 10 5 0
TIME - 10 s/DIV
100 10 CAPACITANCE - pF
1k
1
1k 10 100 CAPACITANCE - pF
10k
Figure 19. Small Signal Transient Response
Figure 20. Small Signal Overshoot vs. Load Capacitance
Figure 21. Small Signal Overshoot vs. Load Capacitance
INPUT +200mV INPUT 0V VSY = 15V RL = 10k AV = 100 VIN = 200mV 0V 2V OUTPUT 0V 200mV VSY = 2.5V RL = 10k AV = 100 VIN = 200mV
INPUT
VS = 15V AV = 1
VOLTAGE - 5V/DIV
OUTPUT
+2V 0V OUTPUT
TIME - 40 s/DIV
TIME - 40 s/DIV
TIME - 400 s/DIV
Figure 22. Positive Overvoltage Recovery
Figure 23. Negative Overvoltage Recovery
Figure 24. No Phase Reversal
140 VSY = 120 100
CMRR - dB
140 2.5V 120 100 80 60 40 20 0 PSRR - dB VSY = 15V
140 VSY = 120 +PSRR 100 PSRR 80 60 40 20 0 2.5V
CMRR - dB
80 60 40 20 0
10
100
10k 100k 1k FREQUENCY - Hz
1M
10M
10
100
10k 100k 1k FREQUENCY - Hz
1M
10M
10
100
10k 100k 1k FREQUENCY - Hz
1M
10M
Figure 25. CMRR vs. Frequency
Figure 26. CMRR vs. Frequency
Figure 27. PSRR vs. Frequency
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OP777
140 VSY = 120
VOLTAGE - 1V/DIV
15V
VSY = 5V GAIN = 10M
VSY = 15V GAIN = 10M
PSRR - dB
+PSRR 80 PSRR 60 40 20 0
10
100
10k 100k 1k FREQUENCY - Hz
1M
10M
VOLTAGE - 1V/DIV
100
TIME - 1s/DIV
TIME - 1s/DIV
Figure 28. PSRR vs. Frequency
Figure 29. 0.1 Hz to 10 Hz Input Voltage Noise
Figure 30. 0.1 Hz to 10 Hz Input Voltage Noise
90
90
90
VOLTAGE NOISE DENSITY - nV/ Hz
VSY = 2.5V
VOLTAGE NOISE DENSITY - nV/ Hz
VOLTAGE NOISE DENSITY - nV/ Hz
VSY = 80 70 60 50 40 30 20 10 0 50
15V
VSY = 80 70 60 50 40 30 20 10 0 100
15V
80 70 60 50 40 30 20 10
100 150 FREQUENCY - Hz
200
250
0
100
200 300 FREQUENCY - Hz
400
500
200 300 FREQUENCY - Hz
400
500
Figure 31. Voltage Noise Density
Figure 32. Voltage Noise Density
Figure 33. Voltage Noise Density
40
50
VSY = 2.5V
50 VSY = 5V
SHORT CIRCUIT CURRENT - mA
VOLTAGE NOISE DENSITY - nV/ Hz
SHORT CIRCUIT CURRENT - mA
35 30 25 20 15 10 5 0 0 500 1k 1.5k FREQUENCY - Hz 2.0k 2.5k
40 30 20 10 0 10 20 30 40 50 60 40
40 30 20 10 0 10 20 30 40 50 ISC+ ISC
VSY =
15V
ISC
ISC+
20 0 20 40 60 80 100 120 140 TEMPERATURE - C
60 40
20 0 20 40 60 80 100 120 140 TEMPERATURE - C
Figure 34. Voltage Noise Density
Figure 35. Short Circuit Current vs. Temperature
Figure 36. Short Circuit Current vs. Temperature
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4.95 VSY = 5V IL = 1mA 160 150 VSY = 5V IL = 1mA
14.964 14.962
OUTPUT VOLTAGE HIGH - V
OUTPUT VOLTAGE LOW - mV
OUTPUT VOLTAGE HIGH - V
4.94
VSY = 15V IL = 1mA
140 130 120 110 100 90 80
14.960 14.958 14.956 14.954 14.952 14.950 14.948 14.946
4.93
4.92
4.91
4.90
4.89
60
40
20 0 20 40 60 80 100 120 140 TEMPERATURE - C
70 60
40
20 0 20 40 60 80 100 120 140 TEMPERATURE - C
14.944 60
40
20 0 20 40 60 80 100 120 140 TEMPERATURE - C
Figure 37. Output Voltage High vs. Temperature
Figure 38. Output Voltage Low vs. Temperature
Figure 39. Output Voltage High vs. Temperature
14.930 VSY = 15V IL = 1mA
OUTPUT VOLTAGE LOW - V
1.5 VSY = 15V VCM = 0V TA = 25 C
14.935
1.0
14.940
VOS - V
0.5 0
14.945
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
Figure 40. Output Voltage Low vs. Temperature
Figure 41. Warm-Up Drift
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OP777
BASIC OPERATION
100k 100k 0.27V 100k +3V
The OP777 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 ground-in 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 input bias current figure comparable to that obtained with "Darlington" input stage amplifier but without the drawbacks (i.e., severe penalties for input voltage range, offset, drift and noise). PNP input structure also greatly lowers the noise and reduces the dc input error terms.
Supply Voltage
OP777
100k 0.1V VIN = 1kHz at 400mV p-p
Figure 43. OP777 Configured as a Difference Amplifier Operating at VCM < 0 V
Input Over Voltage Protection
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 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
The OP777 is rated with an input common-mode voltage which extends from minus supply to 1 V of the Positive supply. However, the amplifier can still operate with input voltages slightly below VEE. In Figure 43, OP777 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.
When the input of an amplifier is more than a diode drop below VEE, large currents will flow from the substrate (V- pin) to the input pins which can destroy the device. In the case of OP777, differential voltage equal to the supply voltage will not cause any problem (see Figure 44). OP777 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 series is free from such limitations.
30V
V p-p = 32 V
OP777
Figure 44a. Unity Gain Follower
VOLTAGE - 100 V/DIV
VSY = 15V
VOUT
VIN
VOLTAGE - 5V/DIV
0V VIN
VOUT
TIME - 0.2ms/DIV
Figure 42. Input and Output Signals with VCM < 0 V
TIME - 400 s/DIV
Figure 44b. Input Voltage Can Exceed the Supply Voltage Without Damage
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OP777
Phase Reversal Output Short Circuit
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 has a protection circuit against phase reversal when one or both inputs are forced beyond their input common voltage range. It is not recommended that the parts be continuously driven more than 3 V beyond the rails.
VSY = 15V
The output of the OP777 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
VIN
VOUT
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 and limiting device power dissipation is of prime importance in these designs. Figure 48 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: R2 VOUT = 5 V - x RSENSE x I L R1
VOLTAGE - 5V/DIV
TIME - 400 s/DIV
Figure 45. 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 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
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 transfer characteristic is -2.5 V/A, decreasing from VEE.
5V 2.49k VOUT Q1 5V
100
OP777
0.1 RSENSE RETURN TO GROUND
VOUT = 1mV VIN = 1mV
OP777
Figure 46. Follower Circuit
Figure 48. A Low-Side Load Current Monitor
VOLTAGE - 25mV/DIV
1.0mV
TIME - 10 s/DIV
Figure 47. Rail-to-Rail Operation
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OP777
The OP777 can be very useful in many single supply bridge applications. Figure 49 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 VO = 2R2 = R1 R1 6 1M 4 REF 192 4 3 0.1 F 15V 15V R1 R1(1+ ) V1 R1 10.1k 10pF VO R2 = R2A + R2B IO = R2 V R1 R2B S 11mA R2A 97.3k 3 RG = 10k 10.1k 1M 100k R1 = 100k R2B 2.7k IO + VL RLOAD + 2.5V 2.7V TO 30V 100k
A single supply current source is shown in Figure 51. Large resistors are used to maintain micropower operation. Output current can be adjusted by changing the R2B resistor. Compliance voltage is:
VL VSAT - VS
C3865-2.5-4/00 (rev. 0) 01536
VO
10pF
OP777
2 2.5V
REF 192
OP777
OP777
R1(1+ ) R2 V2
OP777
= 1mA
Figure 49. Linear Response Bridge, Single Supply
Figure 51. Single Supply Current Source
In systems, where dual supplies are available, circuit of Figure 50 could be used to detect bridge outputs that are linearly related to fractional deviation of the bridge.
15V
A single supply instrumentation amplifier using two OP777 amplifiers is shown in Figure 52.
10.1k 2.7V TO 30V
1k
R2 = 1M
1M
2N2222
2.7V TO 30V R1 = 10.1k
REF 192 4 3 20k
OP777
12k R1 R1 R2
OP777
V1 V2
VO
OP777
+15V
+15V
R(1+ )
R 15V
OP777
VO = R2 V R1 REF R = R
VO = 100 (V2 V1) 0.02mV V1 V2 2mV VOUT 29V
290mV
USE MATCHED RESISTORS
OP777
15V
Figure 52. Single Supply Micropower Instrumentation Amplifier
Figure 50. Linear Response Bridge
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
8-Lead SOIC (RM Suffix)
0.122 (3.10) 0.114 (2.90)
8-Lead SOIC (R Suffix)
0.1968 (5.00) 0.1890 (4.80)
8 5 4
8
5
0.122 (3.10) 0.114 (2.90)
1 4
0.199 (5.05) 0.187 (4.75)
0.1574 (4.00) 0.1497 (3.80) 1
0.2440 (6.20) 0.2284 (5.80)
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
PIN 1 0.0098 (0.25) 0.0040 (0.10)
0.0688 (1.75) 0.0532 (1.35)
0.0196 (0.50) x 45 0.0099 (0.25)
0.0500 0.0192 (0.49) SEATING (1.27) 0.0098 (0.25) PLANE BSC 0.0138 (0.35) 0.0075 (0.19)
8 0 0.0500 (1.27) 0.0160 (0.41)
0.028 (0.71) 0.016 (0.41)
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PRINTED IN U.S.A.

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