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INA
145
INA145
For most current data sheet and other product information, visit www.burr-brown.com
Programmable Gain DIFFERENCE AMPLIFIER
FEATURES
q HIGH COMMON-MODE VOLTAGE: +8V at VS = +5V 28V at VS = 15V q DIFFERENTIAL GAIN = 1V/V TO 1000V/V: Set with External Resistors q LOW QUIESCENT CURRENT: 570A q WIDE SUPPLY RANGE: Single Supply: 4.5V to 36V Dual Supplies: 2.25V to 18V q LOW GAIN ERROR: 0.025% q HIGH CMR: 86dB q SO-8 PACKAGE
DESCRIPTION
The INA145 is a precision, unity-gain difference amplifier consisting of a precision op amp with a precision resistor network. Two external resistors set the gain from 1V/V to 1000V/V. The input commonmode voltage range extends beyond the positive and negative rails. On-chip precision resistors are laser-trimmed to achieve accurate gain and high common-mode rejection. Excellent TCR tracking of these resistors assures continued high precision over temperature. The INA145 is available in the SO-8 surface-mount package specified for the extended industrial temperature range, -40C to +85C.
APPLICATIONS
q q q q CURRENT SHUNT MEASUREMENTS SENSOR AMPLIFIER SYNCHRONOUS DEMODULATOR CURRENT AND DIFFERENTIAL LINE RECEIVER q VOLTAGE-CONTROLLED CURRENT SOURCE q BATTERY POWERED SYSTEMS V+ q LOW COST AUTOMOTIVE INSTRUMENTATION 7
- VIN
RG1
RG2
5 R2 40k R5 10k (1%)
2
R1 40k
A2 6
VO VO = (VIN - VIN)(1 + RG2/RG1)
+ -
G=1 R3 40k
A1 R4 40k INA145 4 V- 1 Ref 8 V01
VIN
+
3
International Airport Industrial Park * Mailing Address: PO Box 11400, Tucson, AZ 85734 * Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 * Tel: (520) 746-1111 Twx: 910-952-1111 * Internet: http://www.burr-brown.com/ * Cable: BBRCORP * Telex: 066-6491 * FAX: (520) 889-1510 * Immediate Product Info: (800) 548-6132
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(c)1999 Burr-Brown Corporation
PDS-1567A 1
Printed in U.S.A. December, 1999
INA145
SPECIFICATIONS: VS = 2.25V to 18V
Boldface limits apply over the specified temperature range, TA = -40C to +85C
At TA = +25C, G = 1, RL = 10k connected to ground and ref pin connected to ground unless otherwise noted. INA145UA PARAMETER OFFSET VOLTAGE, VO Input Offset Voltage vs Temperature vs Power Supply vs Time Offset Voltage, V01 INPUT VOLTAGE RANGE Common-Mode Voltage Range Common-Mode Rejection Over Temperature INPUT BIAS CURRENT(2) Bias Current Offset Current INPUT IMPEDANCE Differential (non-inverting input) Differential (inverting input) Common-Mode NOISE Voltage Noise, f = 0.1Hz to 10Hz Voltage Noise Density, f = 1kHz GAIN Gain Equation Initial(1) Gain Error vs Temperature vs Temperature Nonlinearity FREQUENCY RESPONSE Small Signal Bandwidth Slew Rate Settling Time, 0.1% 0.01% Overload Recovery OUTPUT, VO Voltage Output Over Temperature Over Temperature Short-Circuit Current Capacitive Load POWER SUPPLY Specified Voltage Range, Dual Supplies Operating Voltage Range Quiescent Current Over Temperature TEMPERATURE RANGE Specified Range Operating Range Storage Range Thermal Resistance RTI(1, 4) en 2 90 G = 1 to 1000 G = 1 + RG2 /RG1 1 0.01 0.025 0.0002 500 50 0.45 40 90 40 (V-) + 0.15 (V-) + 0.25 (V-) + 0.3 (V-) + 0.5 15 1000 2.25 1.35 VIN = 0, IO = 0 18 18 700 (V+) - 1 (V+) - 1 (V+) - 1.25 (V+) - 1.25 Vp-p nV/Hz V/V V/V % ppm / C % ppm / C % of FS kHz kHz V/s s s s V V V V mA pF V V A A C C C C/W VOS VOS /T PSRR CONDITION RTI(1, 2) VCM = VO = 0V VS = 1.35V to 18V RTI(1, 2) VCM CMRR (VIN+) - (VIN-) = 0V, VO = 0V VCM = 2(V-) to 2(V+) - 2V, RS = 0 VS = 15V VCM = VS /2 IB IOS 2(V-) 76 70 MIN TYP 0.2 See Typical Curve 20 0.3 0.4 MAX 1 60 UNITS mV V/V V/mo mV V dB dB nA nA k k k
2(V+) -2 86 80 50 5 80 27 40
RL = 100k, VO = (V-)+0.15 to (V+)-1, G = 1 RL = 100k, VO = (V-)+0.25 to (V+)-1, G = 1 RL = 10k, VO = (V-)+0.3 to (V+)-1.25, G = 1 RL = 10k, VO = (V-)+0.5 to (V+)-1.25, G = 1 RL = 10k, VO = (V-)+0.3 to (V+)-1.25, G = 1 G=1 G = 10 G = 1, 10V Step G = 1, 10V Step 50% Input Overload RL = 100k, G = 1 RL = 100k, G = 1 RL = 10k, G = 1 RL = 10k, G = 1 Continuous to Common Stable Operation
2 2
0.1 0.1 0.001
10 10
570
800
-40 -55 -55
+85 +125 +125 150
JA
NOTES: (1) Overall difference amplifier configuration. Referred to input pins (VIN+ and VIN-), Gain = 1V/V. Specified with 10k in feedback of A2. (2) Input offset voltage specification includes effects of amplifier's input bias and offset currents. (3) Common-mode voltage range is 2(V-) to 2(V+) - 2V. (4) Includes effects of input current noise and thermal noise contribution of resistor network.
The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes no responsibility for the use of this information, and all use of such information shall be entirely at the user's own risk. Prices and specifications are subject to change without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant any BURR-BROWN product for use in life support devices and/or systems.
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INA145
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SPECIFICATIONS: VS = +5V Single Supply
Boldface limits apply over the specified temperature range, TA = -40C to +85C
At TA = +25C, G = 1, RL = 10k connected to ground and ref pin connected to 2.5V unless otherwise noted. INA145UA PARAMETER OFFSET VOLTAGE, VO Input Offset Voltage VOS vs Temperature VOS /T vs Power Supply Rejection Ratio PSRR vs Time Offset Voltage, V01 INPUT VOLTAGE RANGE Common-Mode Voltage Range Common-Mode Rejection Ratio Over Temperature INPUT BIAS CURRENT(2) Bias Current Offset Current INPUT IMPEDANCE Differential (non-inverting input) Differential (inverting input) Common-Mode NOISE Voltage Noise, f = 0.1Hz to 10Hz Voltage Noise Density, f = 1kHz GAIN Gain Equation Initial(1) Gain Error vs Temperature vs Temperature Nonlinearity FREQUENCY RESPONSE Small Signal Bandwidth Slew Rate Settling Time, 0.1% 0.01% Overload Recovery OUTPUT, VO Voltage Output Over Temperature Over Temperature Short-Circuit Current Capacitive Load POWER SUPPLY Voltage Range, Single Supply Operating Voltage Range Quiescent Current Over Temperature TEMPERATURE RANGE Specified Range Operating Range Storage Range Thermal Resistance RTI(1, 3, 4) en 2 90 G = 1 to 1000 G = 1 + RG2 /RG1 1 0.01 0.025 0.001 500 50 0.45 40 90 40 0.15 0.25 0.3 0.5 15 1000 +4.5 +2.7 VIN = 0, IO = 0 570 +36 +36 700 800 +85 +125 +125 150 4 4 3.75 3.75 Vp-p nV/Hz V/V V/V V/V % ppm / C % ppm / C % of FS kHz kHz V/s s s s V V V V mA pF V V A A C C C C/W VCM CMRR CONDITION RTI(1, 2) VCM = VO = 2.5V VS = 1.35V to 18V RTI(1, 2) VIN+ - VIN- = 0V, VO = 2.5V VCM = -2.5V to +5.5V, RS = 0 -2.5 76 MIN TYP 0.35 See Typical Curve 20 0.3 0.55 MAX 1 60 UNITS mV V/C V/mo mV V dB dB nA nA k k k
5.5 86 80 50 5 80 27 40
IB IOS
RL = 100k, VO = 0.15V to 4V, G = 1 RL = 100k, VO = 0.25V to 4V, G = 1 RL = 10k, VO = 0.3V to 3.75V, G = 1 RL = 10k, VO = 0.5V to 3.75V, G = 1 RL = 10k, VO = +0.3 to +3.75, G = 1 G = 0.1 G=1 G = 1, 10V Step G = 1, 10V Step 50% Input Overload RL = 100k, G = 1 RL = 100k, G = 1 RL = 10k, G = 1 RL = 10k, G = 1 Continuous to Common Stable Operation
2 2
0.1 0.1 0.005
10 10
-40 -55 -55
JA
NOTES: (1) Overall difference amplifier configuration. Referred to input pins (VIN+ and VIN-), Gain = 1V/V. Specified with 10k in feedback of A2. (2) Input offset voltage specification includes effects of amplifier's input bias and offset currents. (3) Includes effects of input current noise and thermal noise contribution of resistor network. (4) Common-mode voltage range with single supply is 2(V+) - 2V - VREF to -VREF.
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INA145
AMPLIFIER A1, A2 PERFORMANCE
Boldface limits apply over the specified temperature range, TA = -40C to +85C
At TA = +25C, G = 1, RL = 10k connected to ground and ref pin connected to ground unless otherwise noted. INA145UA PARAMETER OFFSET VOLTAGE, VO Input Offset Voltage vs Temperature INPUT VOLTAGE RANGE Common-Mode Voltage Range Common-Mode Rejection Ratio OPEN-LOOP GAIN Open Loop Gain INPUT BIAS CURRENT(2) Bias Current Offset Current RESISTOR AT A1 OUTPUT, VO1 Initial Error Temperature Drift Coefficient VOS VOS /T VCM CMRR AOL IB IOS CONDITION RTI(1, 2) VS = 15V, VCM = VO = 0V TA = -40C to +85C VIN+ - VIN- = 0V, VO = 0V VCM = (V-) to (V+) -1 MIN TYP 0.5 MAX UNITS mV V/C V dB dB nA nA k % ppm/C
1
(V-) to (V+) -1 90 110 50 5 10 0.2 50
PIN CONFIGURATION
Top View SO-8
ELECTROSTATIC DISCHARGE SENSITIVITY
This integrated circuit can be damaged by ESD. Burr-Brown recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
Ref
- VIN + VIN
1 2 3 4
8 7 6 5
VO1 V+ VO RG
V-
ABSOLUTE MAXIMUM RATINGS(1)
Supply Voltage, V+ to V- .................................................................... 36V Signal Input Terminals, Voltage ........................................................ 80V Current ....................................................... 1mA Output Short Circuit (to ground) .............................................. Continuous Operating Temperature .................................................. -55C to +125C Storage Temperature ..................................................... -55C to +150C Junction Temperature .................................................................... +150C Lead Temperature (soldering, 10s) ............................................... +240C NOTE: (1) Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may degrade device reliability.
PACKAGE/ORDERING INFORMATION
PACKAGE DRAWING NUMBER 182 SPECIFIED TEMPERATURE RANGE -40C to +85C PACKAGE MARKING INA145UA ORDERING NUMBER(1) INA145UA INA145UA/2K5 TRANSPORT MEDIA Rails Tape and Reel
PRODUCT INA145UA
PACKAGE SO-8
"
"
"
"
"
NOTE: (1) Models with a slash (/) are available only in Tape and Reel in the quantities indicated (e.g., /2K5 indicates 2500 devices per reel). Ordering 2500 pieces of "INA145UA/2K5" will get a single 2500-piece Tape and Reel.
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TYPICAL PERFORMANCE CURVES
At TA = +25C, VS = 15V, G = 1, RL = 10k connected to ground and Ref pin connected to ground, unless otherwise noted.
GAIN vs FREQUENCY 60 G = 100 40
Voltage Gain (dB) Voltage Gain (dB)
GAIN vs FREQUENCY
VS = 15V CL = 1000pF
60 G = 100 40
VS = 15V CL = 200pF 10k G = 10
20 G = 10 0 G=1 -20 100 1K 10K 100K 1M 10M Frequency (Hz)
20
0 G=1 -20 100 1K 10K 100K 1M 10M Frequency (Hz)
COMMON-MODE REJECTION vs FREQUENCY 100
Common-Mode Rejection (dB)
100
POWER SUPPLY REJECTION vs FREQUENCY PSR+ (VS = 15V)
Power Supply Rejection (dB)
80
80
60
60
PSR+ (VS = +5V)
40
40
20
20 PSR- (VS = 15V) 1 10 100 1k 10k 100k
0 10 100 1k 10k 100k 1M 10M Frequency (Hz)
0
Frequency (Hz)
INPUT VOLTAGE NOISE DENSITY 1k
0.1Hz to 10Hz VOLTAGE NOISE (RTI)
Input Voltage Noise (nV/Hz
G=1 100
500nV/div
G = 100 G = 10 10 0.1 1 10 100 Frequency (Hz) 1k 10k 100k
500ms/div
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INA145
TYPICAL PERFORMANCE CURVES
(Cont.)
At TA = +25C, VS = 15V, G = 1, RL = 10k connected to ground and Ref pin connected to ground, unless otherwise noted.
QUIESCENT CURRENT AND SHORT-CIRCUIT CURRENT vs TEMPERATURE 670 650 630 610 590
IQ (A)
SLEW RATE vs TEMPERATURE
20 G=1 ISC 18 16
Sew Rate (V/s)
0.6 G=1 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 -60 -40 -20 0 20 40 60 80 100 120 140 Temperature (C)
14
ISC (mA)
12 10 IQ 8 6 4 2 0 -60 -40 -20 0 20 40 60 80 100 120 140 Temperature (C)
570 550 530 510 490 470
GAIN AND PHASE vs FREQUENCY Op Amp A1 and A2 110 100 90 80 70 60 50 40 30 20 10 0 -10 1 10 100 1k Frequency (Hz) 10k 100k 1M
SETTLING TIME vs LOAD CAPACITANCE 160
G
RL = 10k || 200pF -90 RL = 1nF
140 120
Open-Loop Gain (dB)
G=1 0.01%
G = 10 0.01%
Settling Time (s)
100 80 60 40 20 G=1 0.1% G = 10 0.1%
-135
Phase ()
-180
0 1 10 Load Capacitance (nF) 100
MAXIMUM OUTPUT VOLTAGE SWING vs OUTPUT CURRENT 15 10 +125C 5 0 +125C -5 -25C -10 -15 -0.8 -0.6 +85C +25C +85C -55C -55C
OFFSET VOLTAGE PRODUCTION DISTRIBUTION VS = 2.25V Typical Production Distribution of Packaged Units.
Output Voltage Swing (V)
-0.4
-0.2
-1
0
0.2
0.4
0.6
0.8
Output Current (mA)
Offset Voltage, RTI (mV)
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1
0
2
4
6
8
10
12
14
16
Relative Frequency
-25C +25C
TYPICAL PERFORMANCE CURVES
(Cont.)
At TA = +25C, VS = 15V, G = 1, RL = 10k connected to ground and Ref pin connected to ground, unless otherwise noted.
OFFSET VOLTAGE PRODUCTION DISTRIBUTION
20
OFFSET VOLTAGE DRIFT PRODUCTION DISTRIBUTION VS = 15V 15
VS = 15V
Typical Production Distribution of Packaged Devices
Relative Frequency
Relative Frequency
10
5
0
-1
-0.8
-0.6
-0.4
-0.2
0.2
0.4
0.6
0.8
Offset Voltage, RTI (mV)
SMALL-SIGNAL STEP RESPONSE (G = 1, RL = 10k, CL = 200pF)
50mV/div
5s/div
50mV/div
SMALL-SIGNAL STEP RESPONSE (G = 10, CL = 1000pF)
50mV/div
5V/div
5s/div
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10
0
1
Offset Voltage Drift, RTI (V/C)
SMALL-SIGNAL STEP RESPONSE (G = 1, CL = 1000pF)
5s/div
LARGE-SIGNAL STEP RESPONSE (G = 10, RL = 10k, CL = 200pF)
50s/div
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INA145
APPLICATION INFORMATION
The INA145 is a programmable gain difference amplifier consisting of a gain of 1 difference amplifier and a programmable-gain output buffer stage. Basic circuit connections are shown in Figure 1. Power supply bypass capacitors should be connected close to pins 4 and 7, as shown. The amplifier is programmable in the range of G = 1 to G = 1000 with two external resistors. The output of A1 is connected to the noninverting input of A2 through a 10k resistor which is trimmed to 1% absolute accuracy. The A2 input is available for applications such as a filter or a precision current source. See application figures for examples. OPERATING VOLTAGE The INA145 is fully specified for supply voltages from 2.25V to 18V, with key parameters guaranteed over the temperature range -40C to +85C. The INA145 can be operated with single or dual supplies, with excellent performance. Parameters that vary significantly with operating voltage, load conditions, or temperature are shown in the typical performance curves.
SETTING THE GAIN The gain of the INA145 is set by using two external resistors, RG1 and RG2, according to the equation: G = 1 + RG2 / RG1 For a total gain of 1, A2 is connected as a buffer amplifier with no RG1. A feedback resistor, RG2 = 10k, should be used in the buffer connection. This provides bias current cancellation (in combination with internal R5) to assure specified offset voltage performance. Commonly used values are shown in the table of Figure 1. Resistor values for other gains should be chosen to provide a 10k parallel resistance. COMMON-MODE RANGE The input resistors of the INA145 provides an input common-mode range that extends well beyond the power supply rails. Exact range depends on the power supply voltage and the voltage applied to the Ref terminal (pin 1). To assure proper operation, the voltage at the non-inverting input of A1 (an internal node) must be within its linear operating range. Its voltage is determined by the simple 1:1 voltage divider between pin 3 and pin 1. This voltage must be between V- and (V+) - 1V.
+VS 0.1F
RG1
RG2
RB 7 R1 40k
- VIN
5 R2 40k R5 10k (1%) A1 VO = (VIN - VIN)(1 + RG2/RG1) A2 6 VO
+ -
2
STANDARD 1% RESISTORS R3 40k
+ VIN
R4 40k INA145 4 1 8 V01 -VS
TOTAL GAIN (V/V) 1 2 5 10 20 50 100 200 500 1000
A2 GAIN (V/V) 1 2 5 10 20 50 100 200 500 1000
RG1 (W) (None) 20k 12.4k 11.0k 10.5k 10.2k 10.2k 499 100 100
RG2 (W) 10k 20k 49.9k 100k 200k 499k 1M 100k 49.9k 100k
RB (W) -- -- -- -- -- -- -- 9.53k 10k 10k
3 0.1F
FIGURE 1. Basic Circuit Connections.
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OFFSET TRIM The INA145 is laser-trimmed for low offset voltage and drift. Most applications require no external offset adjustment. Figure 2 shows an optional circuit for trimming the offset voltage. A voltage applied to the Ref terminal will be summed with the output signal. This can be used to null offset voltage. To maintain good common-mode rejection, the source impedance of a signal applied to the Ref terminal should be less than 10 and a resistor added to the positive input terminal should be 10 times that, or 100. Alternatively, the trim voltage can be buffered with an op amp such as the OPA277.
INPUT IMPEDANCE The input impedance of the INA145 is determined by the input resistor network and is approximately 40k. The source impedance at the two input terminals must be nearly equal to maintain good common-mode rejection. A 5 mismatch in impedance between the two inputs will cause the typical common-mode rejection to be degraded to approximately 72dB. Figure 7 shows a common application measuring power supply current through a shunt resistor. The source impedance of the shunt resistor, RS, is balanced by an equal compensation resistor, RC. Source impedances greater than 300 are not recommended, even if they are perfectly matched. Internal resistors are laser trimmed for accurate ratios, not to absolute values. Adding equal resistors greater than 300 can cause a mismatch in the total resistor ratios, degrading CMR.
10k 5 40k
- VIN
40k
10k 10 VIN 40k
+
A2 6
VO
40k
A1
INA145 1 VO1 RT 100k 100k 10 NOTE: Increasing the trim resistor RT will decrease the trim range -15V +15V
Offset Adjustment Range = 15mV, RTI (1.5mV at pin 1)
FIGURE 2. Optional Offset Trim Circuit.
V+ +5V 7 RS 1 2
RG1 10.2k 5
RG2 1M
G = 100 VB IL 10k 6 Load 3 INA145 4 1 8 V+ +5V +7V +10V +15V Max VB 8V 12V 18V 28V VO = 100 ILRS
FIGURE 3. Measuring Current with Shunt Resistor.
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INA145
Pole at 106Hz
10k
G=1
1500pF
5
RG1 10k
RG2 1M
- VIN
2
5
- VIN
6 VO
2
10k 6
VO
VIN
+
3 INA145 1 8
VIN
+
3 INA145 1 8 22nF Pole at 720Hz
G1 G= R3 R3 + R4
R4
R3
FIGURE 4. Noise Filtering.
FIGURE 5. Creating Gains Less Than Unity.
RG2 10k 5 2 R1 R2 0V VO 5V 10k 6 VO Alternate Soft Clamp To Pin 8 VIN
+
- VIN
3
R3
R4 INA145 1 8 1N914 1N4684 (3.3V) 1N914 5.0V or Analog-to-Digital VS 1N914
(1)
Voltage Reference
(1)
NOTE: (1) 1/2 OPA2342 with VS connected to +5V and GND.
FIGURE 6. Clamp Circuits.
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RG1 11k Power Supply For sense resistors (RS) greater than 5, use series compensation resistor (RC) for good common-mode rejection. Sense resistors greater than 200 are not recommended. 2 RC 10
RG2 100k
5
G = 10 VO
6 RS 10 3 INA145 Load 1 8 VO1
FIGURE 7. Current Monitor, G = 1.
+5V
24V 7 2 5
Feedback
8.4k
8k
1V SHUNT R-I Lamp/10 e.g., 0.1 for 1A 3 INA145 4 1 8 10M 6 VO 1V - 50mV 2k 10k
Lamp
FIGURE 8. Comparator Output with Optional Hysteresis Application to Sense Lamp Burn-Out.
RG1 11k RG2 100k
5
- VIN
RG2 10k 5
- VIN
2
2
6
VO
10k
+
6
VO
VIN
3 INA145 1 8 C1 0.1F
R1 1M
+
VIN
3 INA145 1 8
+ - IOUT = (VIN - VIN)/10k
f=
Pole at 1 = 1.6Hz 2R1RC
OPA277
FIGURE 9. AC Coupling (DC Restoration). 11
FIGURE 10. Precision Current Source.
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INA145

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