TI1 INA131APG4 Precision g = 100 instrumentation amplifier Datasheet

®
INA131
INA
131
Precision G = 100
INSTRUMENTATION AMPLIFIER
FEATURES
DESCRIPTION
● LOW OFFSET VOLTAGE: 50µV max
● LOW DRIFT: 0.25µV/°C max
The INA131 is a low cost, general purpose G = 100
instrumentation amplifier offering excellent accuracy.
Its 3-op amp design and small size make it ideal for
a wide range of applications.
● LOW INPUT BIAS CURRENT: 2nA max
● HIGH COMMON-MODE REJECTION:
110dB min
● INPUT OVERVOLTAGE PROTECTION:
±40V
● WIDE SUPPLY RANGE: ±2.25 to ±18V
● LOW QUIESCENT CURRENT: 3mA
● 8-PIN PLASTIC DIP
On-chip laser trimmed resistors accurately set a fixed
gain of 100. The INA131 is laser trimmed to achieve
very low offset voltage (50µV max), drift (0.25µV/°C
max), and high CMR (110dB min). Internal input
protection can withstand up to ±40V inputs without
damage.
The INA131 is available in a 8-pin plastic DIP. They
are specified over the –40°C to +85°C temperature
range.
APPLICATIONS
●
●
●
●
●
BRIDGE AMPLIFIER
THERMOCOUPLE AMPLIFIER
RTD SENSOR AMPLIFIER
MEDICAL INSTRUMENTATION
DATA ACQUISITION
V+
7
–
VIN
2
Over-Voltage
Protection
INA131
A1
5kΩ
1
25kΩ
25kΩ
A3
2.63kΩ
8
+
VIN
3
6
+
–
VO = 100 (VIN – VIN)
25kΩ
Over-Voltage
Protection
5
A2
5kΩ
Ref
25kΩ
4
DIP
V–
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Internet: http://www.burr-brown.com/ • FAXLine: (800) 548-6133 (US/Canada Only) • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132
©
1992 Burr-Brown Corporation
SBOS016
PDS-1144E
Printed in U.S.A. March, 1998
SPECIFICATIONS
At TA = +25°C, VS = ±15V, RL = 2kΩ, unless otherwise noted.
INA131BP
PARAMETER
CONDITIONS
INPUT
Offset Voltage, RTI
Initial
vs Temperature
vs Power Supply
Long-Term Stability
Impedance, Differential
Common-Mode
Input Common-Mode Range
Safe Input Voltage
Common-Mode Rejection
TYP
MAX
±50
±0.25
3
±11
±10
±0.1
0.5
0.2
1010 || 6
1010 || 6
±13.5
110
120
TA = +25°C
TA = TMIN to TMAX
VS = ±2.25V to ±18V
VCM = ±10V, ∆RS = 1kΩ
INA131AP
MIN
MIN
TYP
MAX
UNITS
±125
±1
✻
✻
±25
±0.25
✻
✻
✻
✻
✻
106
110
µV
µV/°C
µV/V
µV/mo
Ω || pF
Ω || pF
V
V
dB
±40
✻
BIAS CURRENT
vs Temperature
±0.5
±8
±2
✻
✻
±5
nA
pA/°C
OFFSET CURRENT
vs Temperature
±0.5
±8
±2
✻
✻
±5
nA
pA/°C
NOISE VOLTAGE, RTI
f = 10Hz
f = 100Hz
f = 1kHz
f = 10kHz
fB = 0.1Hz to 10Hz
Noise Current
f = 10Hz
f= 1kHz
fB = 0.1Hz to 100Hz
RS = 0Ω
GAIN
Gain Error(1)
Resistor Value(2)
Gain vs Temperature
Nonlinearity
OUTPUT
Voltage
Load Capacitance, max
Short Circuit Current
FREQUENCY RESPONSE
Bandwidth, –3dB
Slew Rate
Settling Time, 0.01%
Overload Recovery
POWER SUPPLY
Voltage Range
Current
IO = 5mA, TMIN to TMAX
VS = ±11.4V, RL = 2kΩ
VS = ±2.25V, R L= 2kΩ
Stable Operation
±13.5
±10
±1
VO = ±10V
0.3
50% Overdrive
±2.25
VIN = 0V
TEMPERATURE RANGE
Specification
Operating
θJA
16
12
12
12
0.4
✻
✻
✻
✻
✻
nV/√Hz
nV/√Hz
nV/√Hz
nV/√Hz
µVp-p
0.4
0.2
18
✻
✻
✻
pA/√Hz
pA/√Hz
pAp-p
±0.01
±10
±0.024
±40
✻
✻
±0.1
✻
%
%
±5
±0.0003
±10
±0.002
✻
✻
±20
±0.004
ppm/°C
% of FSR
±13.7
10.5
1.5
1000
+20/–15
✻
✻
✻
70
0.7
100
20
±15
±2.2
–40
–40
✻
±18
±3
✻
85
125
✻
✻
100
✻
✻
✻
✻
✻
V
V
V
pF
mA
✻
✻
✻
✻
kHz
V/µs
µs
µs
✻
✻
✻
✻
✻
V
mA
✻
✻
°C
°C
°C/W
✻ Specification same as INA131BP.
NOTES: (1) RL = 10kΩ. (2) Absolute value of internal gain-setting resistors. (Gain depends on resistor ratios.)
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.
®
INA131
2
ABSOLUTE MAXIMUM RATINGS(1)
PIN CONFIGURATION
Top View
P-Package/8-Pin DIP
RG
1
8
RG
V –IN
2
7
V+
V +IN
3
6
VO
V–
4
5
Ref
Supply Voltage .................................................................................. ±18V
Input Voltage Range .......................................................................... ±40V
Output Short Circuit (to ground) .............................................. Continuous
Operating Temperature .................................................. –40°C to +125°C
Storage Temperature ..................................................... –40°C to +125°C
Junction Temperature .................................................................... +150°C
Lead Temperature (soldering –10s) .............................................. +300°C
NOTE: (1) Stresses above these ratings may cause permanent damage.
ELECTROSTATIC
DISCHARGE SENSITIVITY
PACKAGE/ORDERING INFORMATION
PRODUCT
PACKAGE
PACKAGE
DRAWING
NUMBER(1)
INA131AP
INA131BP
8-Pin Plastic DIP
8-Pin Plastic DIP
006
006
TEMPERATURE
RANGE
–40°C to +85°C
–40°C to +85°C
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.
NOTE: (1) For detailed drawing and dimension table, please see end of data
sheet, or Appendix C of Burr-Brown IC Data Book.
®
3
INA131
TYPICAL PERFORMANCE CURVES
At 25°C, VS = ±15V, unless otherwise noted.
COMMON-MODE REJECTION vs FREQUENCY
GAIN vs FREQUENCY
60
Common-Mode Rejection (dB)
140
Gain (dB)
40
20
0
100
80
60
40
20
0
–20
100
1k
10k
100k
1M
10
10M
100
1k
100k
Frequency (Hz)
INPUT COMMON-MODE VOLTAGE RANGE
vs OUTPUT VOLTAGE
POWER SUPPLY REJECTION
vs FREQUENCY
1M
140
VD/2
5
VD/2
0
Limited by
A2
+ Output
Swing
Power Supply Rejection (dB)
by A 1
Limited
g
ut Swin
tp
u
O
+
10
–
VO
+
–
+
VCM
–5
–10
–15
–15
A3 – Output
Swing Limit
A3 + Output
Swing Limit
Limited
by A
2
– Outpu
t Swing
by A 1
Limited
g
ut Swin
– Outp
Negative Supply
120
100
80
Positive Supply
60
40
20
0
–10
–5
0
5
10
15
10
100
1k
Output Voltage (V)
10k
100k
1M
Frequency (Hz)
INPUT- REFERRED NOISE VOLTAGE
vs FREQUENCY
OFFSET VOLTAGE WARM-UP vs TIME
100
6
Offset Voltage Change (µV)
Input-Referred Noise Voltage (nV/√ Hz)
10k
Frequency (Hz)
15
Common-Mode Voltage (V)
120
10
1
4
2
0
–2
–4
–6
1
10
100
1k
10k
0
Frequency (Hz)
30
45
60
75
90
Time from Power Supply Turn-on (s)
®
INA131
15
4
105
120
TYPICAL PERFORMANCE CURVES (CONT)
At 25°C, VS = ±15V, unless otherwise noted.
INPUT BIAS CURRENT
vs INPUT VOLTAGE
2
3
2
Input Bias Current (mA)
Input Bias and Input Offset Current (nA)
INPUT BIAS AND INPUT OFFSET CURRENT
vs TEMPERATURE
1
±IB
0
IOS
–1
1
0
Common-Mode
(|IB1| + |IB2|)
Differential Mode
–1
–2
–2
–40
–15
10
35
60
–3
–45
85
–30
Temperature (°C)
MAXIMUM OUTPUT SWING vs FREQUENCY
0
15
30
45
SLEW RATE vs TEMPERATURE
32
1.2
28
1.0
24
Slew Rate (V/µs)
Peak-to-Peak Amplitude (V)
–15
Differential Overload Voltage (V)
20
16
12
8
0.8
0.6
0.4
4
0
10
100
1k
10k
100k
0.2
–75
1M
–50
–25
Frequency (Hz)
OUTPUT CURRENT LIMIT vs TEMPERATURE
50
75
100
125
2.8
Quiescent Current (mA)
Short Circuit Current (mA)
25
QUIESCENT CURRENT vs TEMPERATURE
30
25
+|ICL|
20
15
–|ICL|
10
–40
0
Temperature (°C)
–15
10
35
60
2.6
2.4
2.2
2.0
1.8
–75
85
Temperature (°C)
–50
–25
0
25
50
75
100
125
Temperature (°C)
®
5
INA131
TYPICAL PERFORMANCE CURVES (CONT)
At 25°C, VS = ±15V, unless otherwise noted.
POSITIVE SIGNAL SWING vs TEMPERATUE (RL = 2kΩ)
120
2.5
100
2.4
80
Power Dissipation
2.3
60
Quiescent Current
2.2
40
2.1
20
2.0
0
±3
±6
±9
±12
16
12
VS = ±11.4V
10
8
6
4
VS = ±2.25V
2
0
±18
±15
VS = ±15V
14
Output Voltage (V)
2.6
Power Dissipation (mW)
Quiescent Current (mA)
QUIESCENT CURRENT AND POWER DISSIPATION
vs POWER SUPPLY VOLTAGE
0
–75
–50
–25
0
25
50
75
100
125
Temperature (°C)
Power Supply Voltage (V)
LARGE SIGNAL RESPONSE, G = 100
NEGATIVE SIGNAL SWING vs TEMPERATUE (RL = 2kΩ)
–16
VS = ±15V
Output Voltage (V)
–14
–12
+10V
VS = ±11.4V
–10
0
–8
–6
–4
–10V
VS = ±2.25V
–2
0
–75
–50
–25
0
25
50
75
100
125
Temperature (°C)
SMALL SIGNAL RESPONSE, G = 100
INPUT-REFERRED NOISE, 0.1 to 10Hz
+200mV
0.1µV/div
0
–200mV
1s/div
®
INA131
6
device. Absolute accuracy of the internal values is ±40%.
The nominal gain with an external RG resistor can be
calculated by:
APPLICATION INFORMATION
Figure 1 shows the basic connections required for operation
of the INA131. Applications with noisy or high impedance
power supplies may require decoupling capacitors close to
the device pins as shown.
G = 100 + 250 kΩ
RG
The output is referred to the output reference (Ref) terminal
which is normally grounded. This must be a low-impedance
connection to assure good common-mode rejection. A resistance of 5Ω in series with the Ref pin will cause a device
with 110dB CMR to degrade to approximately 106dB CMR.
(1)
Where: RG is the external gain resistor.
Accuracy of the 250kΩ term is ±40%.
The stability and temperature drift of the external gain
setting resistor, RG, also affects gain. RG’s contribution to
gain accuracy and drift can be directly inferred from the
gain equation (1).
SETTING THE GAIN
No external resistors are required for G = 100. On-chip
laser-trimmed resistors set the gain, providing excellent gain
accuracy and temperature stability. Gain is distributed between the input and output stages of the INA131. Bandwidth
is increased by approximately five times (compared to the
INA114 in G = 100). Input common-mode range is also
improved (see “Input Common-Mode Range”).
NOISE PERFORMANCE
The INA131 provides very low noise in most applications.
For differential source impedances less than 1kΩ, the
INA103 may provide lower noise. For source impedances
greater than 50kΩ, the INA111 FET-Input Instrumentation
Amplifier may provide lower noise.
Although the INA131 is primarily intended for fixed
G = 100 applications, the gain can be increased by connecting an external resistor to the RG pins. The internal resistors
are trimmed for precise ratios, not to absolute values, so the
influence of an external resistor will vary from device to
Low frequency noise of the INA131 is approximately
0.4µVp-p measured from 0.1 to 10Hz. This is approximately one-tenth the noise of state-of-the-art chopper-stabilized amplifiers.
V+
0.1µF
Pin numbers are
for DIP packages.
–
VIN
2
Over-Voltage
Protection
7
INA131
A1
5kΩ
1
25kΩ
+
25kΩ
–
)
VO = 100 • (VIN – VIN
6
A3
2.63kΩ
+
8
25kΩ
Load
VO
–
+
VIN
3
Over-Voltage
Protection
5
A2
5kΩ
4
25kΩ
0.1µF
Also drawn in simplified form:
V–
–
VIN
INA131
V+
IN
VO
Ref
FIGURE 1. Basic Connections.
®
7
INA131
OFFSET TRIMMING
The INA131 is laser trimmed for very low offset voltage and
drift. Most applications require no external offset adjustment. Figure 2 shows an optional circuit for trimming the
output offset voltage. The voltage applied to Ref terminal is
summed at the output. Low impedance must be maintained
at this node to assure good common-mode rejection. This is
achieved by buffering trim voltage with an op amp as
shown.
Microphone,
Hydrophone
etc.
INA131
47kΩ
47kΩ
Thermocouple
–
VIN
VO
V+
INA131
+
VIN
100µA
1/2 REF200
Ref
OPA177
±10mV
Adjustment Range
INA131
10kΩ
100Ω
10kΩ
INA131
100Ω
Center-tap provides
bias current return.
100µA
1/2 REF200
FIGURE 3. Providing an Input Common-Mode Current Path.
V–
FIGURE 2. Optional Trimming of Output Offset Voltage.
INA114 and other unity output gain instrumentation amplifiers, the INA131 provides several additional volts of input
common-mode range with full output voltage swing. See the
typical performance curve “Input Common-Mode Range vs
Output Voltage”.
INPUT BIAS CURRENT RETURN PATH
The input impedance of the INA131 is extremely high—
approximately 1010Ω. However, a path must be provided for
the input bias current of both inputs. This input bias current
is typically less than ±1nA (it can be either polarity due to
cancellation circuitry). High input impedance means that
this input bias current changes very little with varying input
voltage.
Input-overload often produces an output voltage that appears
normal. For example, an input voltage of +20V on one input
and +40V on the other input will obviously exceed the linear
common-mode range of both input amplifiers. Since both
input amplifiers are saturated to the nearly the same output
voltage limit, the difference voltage measured by the output
amplifier will be near zero. The output of the INA131 will
be near 0V even though both inputs are overloaded.
Input circuitry must provide a path for this input bias current
if the INA131 is to operate properly. Figure 3 shows various
provisions for an input bias current path. Without a bias
current return path, the inputs will float to a potential which
exceeds the common-mode range of the INA131 and the
input amplifiers will saturate. If the differential source resistance is low, bias current return path can be connected to one
input (see thermocouple example in Figure 3). With higher
source impedance, using two resistors provides a balanced
input with possible advantages of lower input offset voltage
due to bias current and better common-mode rejection.
INPUT PROTECTION
The inputs of the INA131 are individually protected for
voltages up to ±40V. For example, a condition of –40V on
one input and +40V on the other input will not cause
damage. Internal circuitry on each input provides low series
impedance under normal signal conditions. To provide
equivalent protection, series input resistors would contribute
excessive noise. If the input is overloaded, the protection
circuitry limits the input current to a safe value (approximately 1.5mA). The typical performance curve “Input Bias
Current vs Input Voltage” shows this input current limit
behavior. The inputs are protected even if no power supply
voltage is present.
INPUT COMMON-MODE RANGE
The linear common-mode range of the input op amps of the
INA131 is approximately ±13.75V (or 1.25V from the
power supplies). As the output voltage increases, however,
the linear input range is limited by the output voltage swing
of the input amplifiers, A1 and A2. The 5V/V output stage
gain of the INA131 reduces this effect. Compared to the
®
INA131
8
–
VIN
1MΩ
1MΩ
+
VIN
VO
INA131
Ref
Shield is driven at the
common-mode potential.
100Ω
Common-mode resistors have
approximately 0.1% effect
on gain.
OPA602
FIGURE 4. Shield Driver Circuit.
V+
V+
REF200
100µA
Equal line resistance here creates
a small common-mode voltage
which is rejected by INA131.
1
RTD
VO
INA131
2
Ref
RZ
3
VO = 0V at RRTD = RZ
Resistance in this line causes
a small common-mode voltage
which is rejected by INA131.
FIGURE 5. RTD Temperature Measurement Circuit.
V+
2
10.0V
6
REF102
R1
27k Ω
1N4148
(1)
Cu
R2
5.23k Ω
R4
80.6k Ω
4
(2)
R7
1MΩ
INA131
K
Cu
Ref
R3
100Ω
ISA
TYPE
MATERIAL
SEEBECK
COEFFICIENT
(µV/°C)
R2
(R3 = 100Ω)
R4
(R5 + R6 = 100Ω)
E
Chromel
Constantan
58.5
3.48kΩ
56.2kΩ
J
Iron
Constantan
50.2
4.12kΩ
64.9kΩ
K
Chromel
Alumel
39.4
5.23kΩ
80.6kΩ
T
Copper
Constantan
38.0
5.49kΩ
84.5kΩ
VO
R5
50Ω
R6
100Ω
Zero Adj
NOTES: (1) –2.1mV/°C at 200µA. (2) R7 provides down-scale burn-out indication.
FIGURE 6. Thermocouple Amplifier with Cold Junction Compensation.
®
9
INA131
+10V
–
VIN
R
IO =
100 • VIN
R
INA131
+
Ref
Bridge
IB
VO
INA131
A1
Ref
IO
Load
FIGURE 7. Bridge Transducer Amplifier.
–
VIN
+
±1.5nA
1pA
75fA
FIGURE 9. Differential Voltage to Current Converter.
C1
0.1µF
OPA602
R1
1MΩ
f–3dB =
1
2πR1C1
= 1.59Hz
FIGURE 8. AC-Coupled Instrumentation Amplifier.
®
INA131
IB Error
OPA177
OPA602
OPA128
VO
INA131
Ref
A1
10
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pertaining to warranty, patent infringement, and limitation of liability.
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accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent
TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily
performed, except those mandated by government requirements.
Customers are responsible for their applications using TI components.
In order to minimize risks associated with the customer’s applications, adequate design and operating
safeguards must be provided by the customer to minimize inherent or procedural hazards.
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Copyright  2000, Texas Instruments Incorporated
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