®
INA141
1
INA141
INA141
Precision, Low Power, G = 10, 100
INSTRUMENTATION AMPLIFIER
®
FEATURES
LOW OFFSET VOLTAGE: 50µV max
LOW DRIFT: 0.5µV/°C max
ACCURATE GAIN: ±0.05% at G = 10
LOW INPUT BIAS CURRENT: 5nA max
HIGH CMR: 117dB min
INPUTS PROTECTED TO ±40V
WIDE SUPPLY RANGE: ±2.25 to ±18V
LOW QUIESCENT CURRENT: 750µA
8-PIN PLASTIC DIP, SO-8
DESCRIPTION
The INA141 is a low power, general purpose instru-
mentation amplifier offering excellent accuracy. Its
versatile 3-op amp design and small size make it ideal
for a wide range of applications. Current-feedback
input circuitry provides wide bandwidth even at high
gain (200kHz at G = 100).
Simple pin connections set an accurate gain of 10 or
100V/V without external resistors. Internal input pro-
tection can withstand up to ±40V without damage.
The INA141 is laser trimmed for very low offset
voltage (50µV), drift (0.5µV/°C) and high common-
mode rejection (117dB at G = 100). It operates with
power supplies as low as ±2.25V, and quiescent
current is only 750µA—ideal for battery operated
systems.
The INA141 is available in 8-pin plastic DIP, and
SO-8 surface-mount packages, specified for the –40°C
to +85°C temperature range.
INA141
A
1
A
2
A
3
40k40k
40k40k
V
IN
2
1
8
3
6
5
V
IN
V+
V–
INA141
Ref
V
O
+
Over-Voltage
Protection
25k
25k
Over-Voltage
Protection
4
7
G = 10
or
G =100
252
5050
252
APPLICATIONS
BRIDGE AMPLIFIER
THERMOCOUPLE AMPLIFIER
RTD SENSOR AMPLIFIER
MEDICAL INSTRUMENTATION
DATA ACQUISITION
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/ • FAXLine: (800) 548-6133 (US/Canada Only) • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132
PDS-1297B
®
INA141 2
SPECIFICATIONS
At TA = +25°C, VS = ±15V, and RL = 10kΩ, unless otherwise noted.
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.
INA141P, U INA141PA, UA
PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS
INPUT
Offset Voltage, RTI G = 100 ±20 ±50 ±125 µV
G = 10 ±50 ±100 ±250 µV
vs Temperature G = 100 ±0.2 ±0.5 ±1.5 µV/°C
G = 10(2) ±0.5 ±2±2.5 µV/°C
vs Power Supply
V
S
= ±2.25 to ±18V, G = 100
±0.4 ±1±3µV/V
G = 10 ±2±10 ±20 µV/V
Long-Term Stability G = 100 0.2 µV/mo
G = 10 0.5 µV/mo
Impedance, Differential 1010 || 2 || pF
Common-Mode 1010 || 9 || pF
Common-Mode Voltage Range(1) VO = 0V (V+) – 2 (V+) – 1.4 ✻✻ V
(V–) + 2 (V–) + 1.7 ✻✻ V
Safe Input Voltage ±40 V
Common-Mode Rejection VCM = ±13V, RS = 1k
G = 100 117 125 110 120 dB
G = 10 100 106 93 100 dB
BIAS CURRENT ±2±5±10 nA
vs Temperature ±30 pA/°C
Offset Current ±1±5±10 nA
vs Temperature ±30 pA/°C
NOISE VOLTAGE, RTI
f = 10Hz G = 100, RS = 010 nV/Hz
f = 100Hz 8 nV/Hz
f = 1kHz 8 nV/Hz
fB = 0.1Hz to 10Hz 0.2 µVp-p
f = 10Hz G = 10, RS = 022 nV/Hz
f = 100Hz 13 nV/Hz
f = 1kHz 12 nV/Hz
fB = 0.1Hz to 10Hz 0.6 µVp-p
Noise Current
f = 10Hz 0.9 pA/Hz
f = 1kHz 0.3 pA/Hz
fB = 0.1Hz to 10Hz 30 pAp-p
GAIN
Gain Error VO = ±13.6V, G = 100 ±0.03 ±0.075 ±0.15 %
G = 10 ±0.01 ±0.05 ±0.15 %
Gain vs Temperature(2) G = 10, 100 ±2±10 ✻✻ppm/°C
Nonlinearity G = 100 ±0.0005 ±0.002 ±0.004 % of FSR
G = 10 ±0.0003 ±0.001 ±0.002 % of FSR
OUTPUT
Voltage: Positive RL = 10k(V+) – 1.4 (V+) – 0.9 ✻✻ V
Negative RL = 10k(V–) + 1.4 (V–) + 0.9 ✻✻ V
Load Capacitance Stability 1000 pF
Short-Circuit Current +6/–15 mA
FREQUENCY RESPONSE
Bandwidth, –3dB G = 100 200 kHz
G = 10 1 MHz
Slew Rate VO = ±10V, G = 10 4 V/µs
Settling Time, 0.01% VO = ±5V, G = 100 9 µs
G = 10 7 µs
Overload Recovery 50% Overdrive 4 µs
POWER SUPPLY
Voltage Range ±2.25 ±15 ±18 ✻✻ V
Current, Total VIN = 0V ±750 ±800 ✻✻µA
TEMPERATURE RANGE
Specification –40 85 ✻✻°C
Operating –40 125 ✻✻°C
θ
JA 8-Pin DIP 80 °C/W
SO-8 SOIC 150 °C/W
Specification same as INA141P, U.
NOTE: (1) Input common-mode range varies with output voltage—see typical curves. (2) Guaranteed by wafer test.
®
INA141
3
J
V
IN
V
+IN
V–
J
V+
V
O
Ref
1
2
3
4
8
7
6
5
Top View
PIN CONFIGURATION
8-Pin DIP and SO-8
Supply Voltage .................................................................................. ±18V
Analog 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
ABSOLUTE MAXIMUM RATINGS
ELECTROSTATIC
DISCHARGE SENSITIVITY
This integrated circuit can be damaged by ESD. Burr-Brown
recommends that all integrated circuits be handled with ap-
propriate 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.
ORDERING INFORMATION
PACKAGE
DRAWING TEMPERATURE
PRODUCT PACKAGE NUMBER(1) RANGE
INA141PA 8-Pin Plastic DIP 006 –40°C to +85°C
INA141P 8-Pin Plastic DIP 006 –40°C to +85°C
INA141UA SO-8 Surface-Mount 182 –40°C to +85°C
INA141U SO-8 Surface-Mount 182 –40°C to +85°C
NOTE: (1) For detailed drawing and dimension table, please see end of data
sheet, or Appendix C of Burr-Brown IC Data Book.
®
INA141 4
TYPICAL PERFORMANCE CURVES
At TA = +25°C and VS = ±15V, unless otherwise noted.
GAIN vs FREQUENCY
60
50
40
30
20
10
0
–10
–20
Gain (dB)
Frequency (Hz)
1k 10k 100k 1M 10M
G = 100V/V
G = 10V/V
POSITIVE POWER SUPPLY REJECTION
vs FREQUENCY
Frequency (Hz)
Power Supply Rejection (dB)
140
120
100
80
60
40
20
010 100 1k 10k 100k 1M
G = 100V/V
G = 10V/V
INPUT COMMON-MODE RANGE
vs OUTPUT VOLTAGE, VS = ±5, ±2.5V
Output Voltage (V)
Common-Mode Voltage (V)
–5
5
4
3
2
1
0
–1
–2
–3
–4
–5 –4 –3 –2 –1 0 1 2 3 4 5
VS = ±5V
VS = ±2.5V
COMMON-MODE REJECTION vs FREQUENCY
Frequency (Hz)
Common-Mode Rejection (dB)
10 100 10k 1M1k
140
120
100
80
60
40
20
0100k
G = 10V/V
G = 100V/V
NEGATIVE POWER SUPPLY REJECTION
vs FREQUENCY
Frequency (Hz)
Power Supply Rejection (dB)
140
120
100
80
60
40
20
010 100 1k 10k 100k 1M
G = 100V/V
G = 10V/V
INPUT COMMON-MODE RANGE
vs OUTPUT VOLTAGE, V
S
= ±15V
Output Voltage (V)
Common-Mode Voltage (V)
–15 –10 0 5 15–5
15
10
5
0
–5
–10
–15 10
V
D/2
+
+
V
CM
V
O
V
D/2
Ref
–15V
+15V
+
®
INA141
5
INPUT OFFSET VOLTAGE WARM-UP
10
8
6
4
2
0
–2
–4
–6
–8
–10 0100 200 300 400 500
Time (µs)
Input Offset Voltage Change (µV)
TYPICAL PERFORMANCE CURVES (CONT)
At TA = +25°C and VS = ±15V, unless otherwise noted.
OUTPUT VOLTAGE SWING
vs OUTPUT CURRENT
(V+)
(V+)–0.4
(V+)–0.8
(V+)–1.2
(V+)+1.2
(V–)+0.8
(V–)+0.4
V– 01234
Output Current (mA)
Output Voltage (V)
INPUT- REFERRED NOISE vs FREQUENCY
Frequency (Hz)
Input-Referred Voltage Noise (nV/ Hz)
110 1k100
1k
100
10
110k
G = 10V/V
100
10
1
0.1
Input Bias Current Noise (pA/ Hz)
Current Noise
G = 100V/V
INPUT OVER-VOLTAGE V/I CHARACTERISTICS
5
4
3
2
1
0
–1
–2
–3
–4
–5
Input Current (mA)
Input Voltage (V)
–50 –40 –30 –20 –10 10 20 30 40050
G = 10V/V
G = 10V/V
G = 100V/V
G = 100V/V V
IN
I
IN
–15V
+15V
INA141
Flat region represents
normal linear operation.
QUIESCENT CURRENT and SLEW RATE
vs TEMPERATURE
Temperature (°C)
Quiescent Current (µA)
0.9
0.85
0.8
0.75
0.7
0.65
6
5
4
3
2
1
–75 –50 –25 0 25 50 75 100 125
Slew Rate (V/µs)
IQ
Slew Rate
INPUT BIAS CURRENT vs TEMPERATURE
2
1
0
–1
–2–75 –50 –25 0 25 50 75 100 125
Temperature (°C)
Input Bias Current (nA)
I
OS
I
B
Typical I
B
Range
±2nA at 25°C
®
INA141 6
TYPICAL PERFORMANCE CURVES (CONT)
At TA = +25°C and VS = ±15V, unless otherwise noted.
OUTPUT VOLTAGE SWING
vs POWER SUPPLY VOLTAGE
V+
(V+)–0.4
(V+)–0.8
(V+)–1.2
(V–)+1.2
(V–)+0.8
(V–)+0.4
V– 0 5 10 15 20
Power Supply Voltage (V)
Output Voltage Swing (V)
+25°C +85°C
–40°C
+25°C
–40°C
+85°C
R
L
= 10k
+85°C
–40°C
SHORT-CIRCUIT OUTPUT CURRENT
vs TEMPERATURE
18
16
14
12
10
8
6
4
2
0–75 –50 –25 0 25 50 75 100 125
Temperature (°C)
Short-Circuit Current (mA)
–I
SC
+I
SC
MAXIMUM OUTPUT VOLTAGE vs FREQUENCY
Frequency (Hz)
Peak-to-Peak Output Voltage (Vpp)
30
25
20
15
10
5
01k 10k 100k 1M
G = 10, 100
TOTAL HARMONIC DISTORTION + NOISE
vs FREQUENCY
Frequency (Hz)
THD+N (%)
100 1k 10k
1
0.1
0.01
0.001 100k
V
O
= 1Vrms
G = 10V/V
R
L
= 100k
G = 100, R
L
= 100k
R
L
= 10k
500kHz Measurement
Bandwidth
Dashed Portion
is noise limited.
®
INA141
7
TYPICAL PERFORMANCE CURVES (CONT)
At TA = +25°C and VS = ±15V, unless otherwise noted.
G = 10
G = 100
G = 10
G = 100
5µs/div5µs/div
LARGE-SIGNAL STEP RESPONSE
SMALL-SIGNAL STEP RESPONSE
VOLTAGE NOISE 0.1 to 10Hz
INPUT-REFERRED, G = 100
1s/div
0.1µV/div
20mV/div 5V/div
®
INA141 8
APPLICATION INFORMATION
Figure 1 shows the basic connections required for operation
of the INA141. Applications with noisy or high impedance
power supplies may require decoupling capacitors close to
the device pins as shown.
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 resis-
tance of 8 in series with the Ref pin will cause a typical
device to degrade to approximately 80dB CMR (G = 1).
SETTING THE GAIN
Gain is selected with a jumper connection as shown in
Figure 1. G = 10V/V with no jumper installed. With a
jumper installed, G = 100V/V. To preserve good gain
accuracy, this jumper must have low series resistance. A
resistance of 0.5 in series with the jumper will decrease the
gain by 0.1%.
Internal resistor ratios are laser trimmed to assure excellent
gain accuracy. Actual resistor values can vary by approxi-
mately ±25% from the nominal values shown.
Gains between 10 and 100 can be achieved by connecting an
external resistor to the jumper pins. This is not recom-
mended, however, because the ±25% variation of internal
resistor values makes the required external resistor value
uncertain. A companion model, INA128, features accurately
trimmed internal resistors so that gains from 1 to 10,000 can
be set with an external resistor.
DYNAMIC PERFORMANCE
The typical performance curve “Gain vs Frequency” shows
that, despite its low quiescent current, the INA141 achieves
wide bandwidth, even at G = 100. This is due to the current-
feedback topology of the INA141. Settling time also re-
mains excellent at G = 100.
NOISE PERFORMANCE
The INA141 provides very low noise in most applications.
Low frequency noise is approximately 0.2µVp-p measured
from 0.1 to 10Hz (G = 100). This provides dramatically
improved noise when compared to state-of-the-art chopper-
stabilized amplifiers.
FIGURE 1. Basic Connections.
A1
A2
A36
40k40k
40k40k
7
4
3
8
1
2
VIN
VIN
V+
V–
INA141
+5
Over-Voltage
Protection
25k
25k
Over-Voltage
Protection
Load
VO = G • (VIN – VIN)
+
0.1µF
0.1µF
+
VO
Also drawn in simplified form:
INA141
Ref
VO
VIN
VIN
+
Ref
G = 10
(no connection)
or
G = 100
(connect jumper)
252
5050
252
®
INA141
9
FIGURE 3. Providing an Input Common-Mode Current Path.
OFFSET TRIMMING
The INA141 is laser trimmed for low offset voltage and
offset voltage 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 with the output. The op amp buffer
provides low impedance at the Ref terminal to preserve good
common-mode rejection.
FIGURE 2. Optional Trimming of Output Offset Voltage.
INPUT BIAS CURRENT RETURN PATH
The input impedance of the INA141 is extremely high—
approximately 1010. However, a path must be provided for
the input bias current of both inputs. This input bias current
is approximately ±2nA. High input impedance means that
this input bias current changes very little with varying input
voltage.
Input circuitry must provide a path for this input bias current
for proper operation. Figure 3 shows various provisions for
an input bias current path. Without a bias current path, the
inputs will float to a potential which exceeds the common-
mode range of the INA141 and the input amplifiers will
saturate.
If the differential source resistance is low, the bias current
return path can be connected to one input (see the thermo-
couple example in Figure 3). With higher source impedance,
using two equal resistors provides a balanced input with
possible advantages of lower input offset voltage due to bias
current and better high-frequency common-mode rejection.
INPUT COMMON-MODE RANGE
The linear input voltage range of the input circuitry of the
INA141 is from approximately 1.4V below the positive
supply voltage to 1.7V above the negative supply. As a
differential input voltage causes the output voltage to in-
crease, however, the linear input range will be limited by the
output voltage swing of amplifiers A1 and A2. So the linear
common-mode input range is related to the output voltage of
the complete amplifier. This behavior also depends on sup-
ply voltage—see performance curves “Input Common-Mode
Range vs Output Voltage”.
Input overload can produce an output voltage that appears
normal. For example, if an input overload condition drives
both input amplifiers to their positive output swing limit, the
difference voltage measured by the output amplifier will be
near zero. The output of the INA141 will be near 0V even
though both inputs are overloaded.
LOW VOLTAGE OPERATION
The INA141 can be operated on power supplies as low as
±2.25V. Performance remains excellent with power supplies
ranging from ±2.25V to ±18V. Most parameters vary only
slightly through this supply voltage range—see Typical
Performance Curves. Operation at very low supply voltage
requires careful attention to assure that the input voltages
remain within their linear range. Voltage swing require-
ments of internal nodes limit the input common-mode range
with low power supply voltage. Typical performance curves,
“Input Common-Mode Range vs Output Voltage” show the
range of linear operation for ±15V, ±5, and ±2.5V supplies.
INPUT PROTECTION
The inputs of the INA141 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 of approxi-
mately 1.5 to 5mA. The typical performance curve “Input
Bias Current vs Common-Mode Input Voltage” shows this
input current limit behavior. The inputs are protected even if
the power supplies are disconnected or turned off.
10k
OPA177
±10mV
Adjustment Range
100
100
100µA
1/2 REF200
100µA
1/2 REF200
V+
V–
INA141
Ref
V
O
V
IN
V
IN
+
47k47k
10k
Microphone,
Hydrophone
etc.
Thermocouple
Center-tap provides
bias current return.
INA141
INA141
INA141
®
INA141 10
REF102
R
2
R
1
R
3
Pt100
Cu
Cu
V+
K
6
10.0V
4
2
INA141 V
O
Ref
100 = Pt100 at 0°C
FIGURE 4. ECG Amplifier With Right-Leg Drive.
FIGURE 5. Bridge Amplifier.
FIGURE 7. Thermocouple Amplifier With RTD Cold-
Junction Compensation.
SEEBECK
ISA COEFFICIENT
TYPE MATERIAL (µV/°C) R1, R2
E + Chromel 58.5 66.5k
– Constantan
J + Iron 50.2 76.8k
– Constantan
K + Chromel 39.4 97.6k
– Alumel
T + Copper 38.0 102k
– Constantan
INA141 V
O
C
1
0.1µF
OPA602
Ref R
1
1M
f
–3dB
= 1
2πR
1
C
1
= 1.59Hz
V
IN
+
FIGURE 6. AC-Coupled Instrumentation Amplifier.
INA141
I
B
R
1
V
IN
+
A
1
I
O
Load
I
O
= • G
V
IN
R
1
Ref
A1IB Error
OPA177 ±1.5nA
OPA131 50pA
OPA602 ±1pA
OPA128 ±75fA
FIGURE 8. Differential Voltage to Current Converter.
INA141 V
O
LA
RL
RA
10k
Ref G = 10
20k20k
V
G
1/4
OPA4131
390k
390k
1/4
OPA4131
OPA4131
1/4
OPA4131
1/4
300
+5V
2.5V – V
2.5V + V
+15V
–15V
INA141 V
O
Ref