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INA129-EP
SBOS508A – DECEMBER 2009 – REVISED DECEMBER 2015
INA129-EP Precision, Low Power Instrumentation Amplifiers
1 Features
3 Description
•
•
•
•
•
•
The INA129-EP device is a low power, generalpurpose instrumentation amplifier offering excellent
accuracy. The versatile 3-op amp design and small
size make the device ideal for a wide range of
applications. Current-feedback input circuitry provides
wide bandwidth even at high gain (200 kHz at G =
100).
1
Low Offset Voltage
Low Input Bias Current
High CMR: 95 dB (Typical)
Inputs Protected to ±40 V
Wide Supply Range: ±2.25 V to ±18 V
Low Quiescent Current: 2 mA (Typical)
A single external resistor sets any gain from 1 to
10,000. The INA129-EP provides an industrystandard gain equation; the INA129-EP gain equation
is compatible with the AD620.
2 Applications
•
•
•
•
•
•
(1)
Bridge Amplifier
Thermocouple Amplifier
RTD Sensor Amplifier
Medical Instrumentation
Data Acquisition
Supports Extreme Temperature Applications:
– Controlled Baseline
– One Assembly and Test Site
– One Fabrication Site
– Available in Military (–55°C to +125°C)
Temperature Range (1)
– Extended Product Life Cycle
– Extended Product-Change Notification
– Product Traceability
The INA129-EP device is laser trimmed for very low
offset voltage, drift, and high common-mode rejection
(113 dB at G ≥ 100). It operates with power supplies
as low as ±2.25 V, and quiescent current is only 750
μA–ideal for battery operated systems. Internal input
protection can withstand up to ±40 V without damage.
The INA129-EP is available in a 8-Pin SOIC surfacemount package specified for the –55°C to 125°C
temperature range.
Device Information(1)
PART NUMBER
INA129-EP
PACKAGE
SOIC (8)
BODY SIZE (NOM)
4.90 mm × 3.91 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Custom temperature ranges available
Simplified Schematic
V+
7
G=1+
INA129
2
VIN
49.4 kW
RG
Over-Voltage
Protection
A1
40 kW
1
A3
RG
8
+
VIN
40 kW
24.7 kW
3
6
VO
24.7 kW
Over-Voltage
Protection
5
A2
40 kW
Ref
40 kW
4
V-
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
INA129-EP
SBOS508A – DECEMBER 2009 – REVISED DECEMBER 2015
www.ti.com
Table of Contents
1
2
3
4
5
6
7
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
5
6.1
6.2
6.3
6.4
6.5
6.6
5
5
5
5
6
8
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description ............................................ 11
7.1 Overview ................................................................. 11
7.2 Functional Block Diagram ....................................... 11
7.3 Feature Description................................................. 11
7.4 Device Functional Modes........................................ 12
8
Application and Implementation ........................ 13
8.1 Application Information............................................ 13
8.2 Typical Application ................................................. 13
9
Power Supply Recommendations...................... 17
9.1 Low Voltage Operation ........................................... 17
10 Layout................................................................... 18
10.1 Layout Guidelines ................................................. 18
10.2 Layout Example .................................................... 18
11 Device and Documentation Support ................. 19
11.1
11.2
11.3
11.4
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
19
19
19
19
12 Mechanical, Packaging, and Orderable
Information ........................................................... 19
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Original (December 2009) to Revision A
Page
•
Added ESD Ratings table, Feature Description section, Device Functional Modes, Application and Implementation
section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and
Mechanical, Packaging, and Orderable Information section ................................................................................................. 1
•
Removed junction-to-ambient thermal resistance value for 8-pin DIP package, and updated SOIC package thermal
information. ............................................................................................................................................................................ 5
2
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SBOS508A – DECEMBER 2009 – REVISED DECEMBER 2015
5 Pin Configuration and Functions
D Package
8-Pin SOIC
Top View
RG
1
8
RG
V- IN
2
7
V+
V+IN
3
6
VO
V-
4
5
Ref
Pin Functions
PIN
NAME
NO.
I/O
DESCRIPTION
Ref
5
I
Output voltage reference
RG
1, 8
O
Gain resistor connection
V+
7
Power
Positive power supply voltage from 2.25 V to 18 V
V–
4
Power
Negative power supply voltage from –2.25 V to –18 V
V+IN
3
I
Non-inverting input voltage
V–IN
2
I
Inverting input voltage
VO
6
O
Output voltage
Bare Die Information
DIE THICKNESS
BACKSIDE FINISH
BACKSIDE
POTENTIAL
BOND PAD
METALLIZATION COMPOSITION
15 mils
Silicon with backgrind
GND
Al-Si-Cu (0.5%)
Origin
a
c
b
d
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Bond Pad Coordinates in Mils
(1)
DESCRIPTION
PAD NUMBER
a
b
c
d
NC
1
-57.4
-31.1
-53.3
-27
V-IN
2
-9.85
-31.4
-5.75
-27.3
V+IN
3
25.05
-31.4
29.15
-27.3
-30.2
V-
4
56.2
-34.3
60.3
Ref
5
53.75
-17.6
57.85
-11
VO
6
50.35
27.8
56.95
31.9
V+
7
7.75
30.2
11.85
34.3
32.5
NC
8
-57.4
28.4
-53.3
RG (1)
9
-57.4
13.4
-53.3
20
RG (1)
10
-57.5
2.7
-53.4
9.3
RG (1)
11
-57.5
-7.9
-53.4
-1.3
RG (1)
12
-57.4
-18.6
-53.3
-12
Pads 9 and 10 must both be bonded to a common point and correspond to package pin 8. Pads 11 and 12 must both be bonded to a
common point and correspond to package pin 1.
NC
RG
RG
RG
RG
NC
PAD #1
V-IN
V+
V+IN
VO
V-
4
Ref
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6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)
(1)
MIN
VS
MAX
UNIT
±18
V
±40
V
125
°C
Supply voltage
Analog input voltage
Output short-circuit (to ground)
Continuous
TA
Operating temperature
TJ
Junction temperature
150
°C
Lead temperature (soldering, 10s)
300
°C
125
°C
Tstg
(1)
–55
Storage temperature
–55
Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may
degrade device reliability. These are stress ratings only, and functional operation of the device at these or any other conditions beyond
those specified is not implied.
6.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic discharge
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins (1)
±4000
Charged device model (CDM), per JEDEC specification JESD22-C101, all
pins (2)
±200
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
V power supply
Input common-mode voltage range for VO = 0
TA operating temperature INA129-EP
MIN
NOM
MAX
UNIT
±2.25
±15
±18
V
V-2V
V + –2 V
–55
125
°C
6.4 Thermal Information
INA129-EP
THERMAL METRIC (1)
D (SOIC)
UNIT
8 PINS
RθJA
Junction-to-ambient thermal resistance
110
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
57
°C/W
RθJB
Junction-to-board thermal resistance
54
°C/W
ψJT
Junction-to-top characterization parameter
11
°C/W
ψJB
Junction-to-board characterization parameter
53
°C/W
(1)
For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.
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6.5 Electrical Characteristics
At TA = 25°C, VS = ±15 V, RL = 10 kΩ (unless otherwise noted)
PARAMETER
TEST CONDITIONS
TA = 25°C
MIN
TA = 25°C
TYP
MAX
MIN
TYP
MAX
UNIT
INPUT
Offset Voltage, RTI
±100
±800/G
TA = 25°C
Initial
±150
±2050/G
Overtemperature
vs power supply
TA = 25°C, VS = ±2.25 V to ±18
V
±1.6
±175/G
±1.8
±175/G
Overtemperature
µV
µV/V
Long-term stability
±1 ±3/G
µV/mo
Impedance, differential
1010 || 2
Ω || pF
1011||9
Ω || pF
Common mode
Common mode voltage
range (1)
VO = 0 V
(V+) −
2
(V+) − 1.4
V
(V−) +
2
(V−) + 1.7
V
75
86
Safe input voltage
±40
G=1
Overtemperature
G = 10
VCM = ±13 V, Overtemperature
Common-mode rejection
ΔRS = 1 kΩ
G = 100
67
93
106
113
125
84
Overtemperature
G = 1000
V
dB
98
113
130
Overtemperature
98
CURRENT
Bias current
Offset Current
±2
±8
Overtemperature
±16
±1
±8
Overtemperature
±16
nA
nA
NOISE
Noise voltage, RTI
Noise current
G = 1000,
RS = 0 Ω
G = 1000,
RS = 0 Ω
f = 10 Hz
10
f = 100 Hz
8
f = 1 kHz
8
nV/√Hz
fB = 0.1 Hz to 10
Hz
0.2
f = 10 Hz
0.9
f = 1 kHz
0.3
fB = 0.1 Hz to 10
Hz
30
pAPP
1+
(49.4
kΩ/RG)
V/V
µVpp
pA/√Hz
GAIN
Gain equation
Range of gain
(1)
6
1
10000
V/V
Input common-mode range varies with output voltage — see Typical Characteristics.
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Electrical Characteristics (continued)
At TA = 25°C, VS = ±15 V, RL = 10 kΩ (unless otherwise noted)
PARAMETER
TEST CONDITIONS
TA = 25°C
MIN
G=1
TA = 25°C
TYP
MAX
±0.05%
±0.1%
MIN
Overtemperature
±0.02%
±0.5%
±0.05%
±0.65%
Overtemperature
±0.65%
G = 100
Overtemperature
±1.1%
G = 1000
Gain vs temperature (2)
G=1
49.4-kΩ
resistance (2) (3)
VO = ±13.6 V,
G=1
±0.5%
±2%
±1
±10
ppm/°C
±25
±100
ppm/°C
±0.0001
±0.0018
Overtemperature
±0.0035
G = 10
Nonlinearity
UNIT
MAX
±0.15%
G = 10
Gain error
TYP
±0.0003
±0.0035
Overtemperature
±0.0055
G = 100
±0.0005
% of
FSR
±0.0035
Overtemperature
±0.0055
G = 1000
±0.001
See
(4)
OUTPUT
Positive
RL = 10 kΩ
(V+) −
1.4
(V+) − 0.9
Negative
RL = 10 kΩ
(V−) +
1.4
(V−) + 0.8
Voltage
Load capacitance
stability
Short-circuit current
V
1000
pF
+6/−15
mA
FREQUENCY RESPONSE
Bandwidth, −3 dB
Slew rate
Settling time, 0.01%
Overload recovery
G=1
1300
G = 10
700
G = 100
200
G = 1000
20
VO = ±10 V,
G = 10
4
G=1
7
G = 10
7
G = 100
9
G = 1000
80
50% overdrive
kHz
V/µs
µs
4
µs
POWER SUPPLY
Voltage range
Current, total
±2.25
VIN = 0 V
±15
±18
±700
±750
V
Overtemperature
±1200
µA
TEMPERATURE RANGE
Specification
−55
125
°C
Operating
−55
125
°C
(2)
(3)
(4)
Specified by wafer test.
Temperature coefficient of the 49.4-kΩ term in the gain equation.
Nonlinearity measurements in G = 1000 are dominated by noise. Typical nonlinearity is ±0.001%.
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6.6 Typical Characteristics
At TA = 25°C, VS = ±15 V, unless otherwise noted.
60
140
G =1000V/V
G =100V/V
G = 1000V/V
Common-Mode Rejection (dB)
50
40
Gain (dB)
G = 100V/V
30
20
G = 10 V/V
10
0
G = 1V/V
− 10
120
G =10V/V
100
G =1V/V
80
60
40
20
− 20
0
10k
1k
100k
10M
1M
10
100
10k
1k
Frequency (Hz)
100k
1M
Frequency (Hz)
Figure 1. Gain vs Frequency
Figure 2. Common-Mode Rejection vs Frequency
140
140
Power Supply Rejection (dB)
Power Supply Rejection (dB)
G = 1000V/V
120
G =1000V/V
100
G =100V/V
80
60
G= 10V/V
40
G=1V/V
20
120
80
60
100
10k
1k
100k
G=1V/V
20
0
10
1M
Frequency (Hz)
Frequency (Hz)
Figure 3. Positive Power-Supply Rejection vs Frequency
Figure 4. Negative Power-Supply Rejection vs Frequency
5
15
G ≥ 10
G ≥ 10
G=1
G=1
5
+15V
VD/2
0
VD/2
5
+
VO
Ref
+
VCM
-15V
10
3
2
G=1
G=1
G ≥ 10
1
0
G=1
1
2
3
VS = ±5V
VS = ±2.5V
4
5
15
-15
-10
-5
0
5
10
15
-5
-4
-3
-2
-1
0
1
2
3
4
5
Output Voltage (V)
Output Voltage (V)
VS = ±5 V, ±2.5 V
VS = ±15 V
Figure 5. Input Common-Mode Range vs Output Voltage
8
G ≥ 10
G ≥ 10
4
10
Common-Mode Voltage (V)
Common-Mode Voltage (V)
G=10V/V
40
0
10
G =100V/V
100
Figure 6. Input Common-Mode Range vs Output Voltage
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Typical Characteristics (continued)
1k
100
100
¾
Input Bias Current Noise (pA/√Hz)
¾
G = 1V / V
100
10
G =10V/V
10
1
G =100, 1000V/V
Current Noise
1
0.01%
Settling Time (ms)
Input-Referred Voltage Noise (nV/√Hz)
At TA = 25°C, VS = ±15 V, unless otherwise noted.
0.1%
10
1
0.1
1
10
100
10
1
10k
1k
Figure 7. Input-Referred Noise vs Frequency
4
8
Input Current (mA)
Flat region represents
normal linear operation.
Offset Voltage Change (mV)
10
2
G = 1000V/V
1
G = 1V / V
0
1
+15V
G=1V/V
2
3
VIN
G = 1000V/V
4
6
4
2
0
-2
-4
-6
-8
IIN 15V
5
-10
-50
-40
-30
-20
-10
0
10
20
30
40
200
100
0
50
500
400
300
Input Voltage (V)
Time (ms)
Figure 9. Input Overvoltage Voltage-to-Current
Characteristics
Figure 10. Input Offset Voltage Warm-Up
(V+)
(V+)
(V+)-0.4
(V+)-0.4
Output Voltage Swing (V)
Output Voltage (V)
1000
Figure 8. Settling Time vs Gain
5
3
100
Gain (V/V)
Frequency (Hz)
(V+)-0.8
(V+)-1.2
(V-)+1.2
(V-)+0.8
+25°C
(V+)-0.8
(V+)-1.2
+85°C
-40 °C
RL = 10 k Ω
+25°C
(V-)+1.2
-40 °C
+85°C
(V-)+0.8
+85°C
-40 °C
(V-)+0.4
(V-)+0.4
(V-)
(V-)
0
1
2
3
4
0
5
10
15
20
Power Supply Voltage (V)
Output Current (mA)
Figure 11. Output Voltage Swing vs Output Current
Figure 12. Output Voltage Swing vs Power Supply Voltage
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Typical Characteristics (continued)
At TA = 25°C, VS = ±15 V, unless otherwise noted.
1
G =10, 100
25
VO = 1 Vrms
500kHz Measurement
Bandwidth
G=1
G = 1000
TH D + N (% )
Peak-to-Peak Output Voltage (VPP)
30
20
15
10
G =100, RL = 100kW
0.01
G =10V/V
RL = 100kW
G =1, RL = 100kW
5
Dashed Portion
is noise limited.
0
1k
10
0.1
G=1
RL = 10kW
10k
100k
1M
0.001
100
1k
10k
100k
Frequency (Hz)
Frequency (Hz)
Figure 13. Maximum Output Voltage vs Frequency
Figure 14. Total Harmonic Distortion + Noise vs Frequency
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7 Detailed Description
7.1 Overview
The INA129-EP instrumentation amplifier is a type of differential amplifier that has been outfitted with input
protection circuit and input buffer amplifiers, which eliminate the need for input impedance matching and make
the amplifier particularly suitable for use in measurement and test equipment. Additional characteristics of the
INA129-EP include a very low DC offset, low drift, low noise, very high open-loop gain, very high common-mode
rejection ratio, and very high input impedances. The INA129-EP is used where great accuracy and stability of the
circuit both short and long-term are required.
7.2 Functional Block Diagram
V+
7
G=1+
INA129
2
VIN
49.4 kW
RG
Over-Voltage
Protection
A1
40 kW
1
A3
RG
8
+
VIN
40 kW
24.7 kW
3
6
VO
24.7 kW
Over-Voltage
Protection
5
A2
40 kW
Ref
40 kW
4
V-
7.3 Feature Description
The INA129-EP device is a low power, general-purpose instrumentation amplifier that offers excellent accuracy.
The versatile three-operational-amplifier design and small size make the amplifier ideal for a wide range of
applications. Current-feedback input circuitry provides wide bandwidth, even at high gain. A single external
resistor sets any gain from 1 to 10,000. The INA129-EP device is laser trimmed for very low offset voltage (50
μV) and high common-mode rejection (93 dB at G ≥ 100). This device operates with power supplies as low as
±2.25 V, and quiescent current of 2 mA, typically. The internal input protection can withstand up to ±40 V without
damage.
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7.4 Device Functional Modes
A single external resistor sets the any gain from 1 to 10000. TI INA129-EP provides an industry standard gain
equation, as highlighted in Figure 16.
7.4.1 Noise Performance
The INA129-EP provides very low noise in most applications. Low frequency noise is approximately 0.2 μVPP
measured from 0.1 Hz to 10 Hz (G ≥ 100). This provides dramatically improved noise when compared to stateof-the-art chopper-stabilized amplifiers.
0.1mV/div
1s/div
G ≥ 100
Figure 15. 0.1-Hz to 10-Hz Input-Referred Voltage Noise
7.4.2 Input Common-Mode Range
The linear input voltage range of the input circuitry of the INA129-EP is from approximately 1.4 V below the
positive supply voltage to 1.7 V above the negative supply. As a differential input voltage causes the output
voltage increase, 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 supply voltage (see Figure 5 and Figure 6).
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 A3 will be near 0 V even though both inputs are overloaded.
12
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8 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
The INA129-EP device measures small differential voltage with high common-mode voltage developed between
the non-inverting and inverting input. The high-input voltage protection circuit in conjunction with high input
impedance make the INA129-EP suitable for a wide range of applications. The ability to set the reference pin to
adjust the functionality of the output signal offers additional flexibility that is practical for multiple configurations.
8.2 Typical Application
Figure 16 shows the basic connections required for operation of the INA129-EP. 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 lowimpedance connection to assure good common-mode rejection. A resistance of 8 Ω in series with the Ref pin will
cause a typical device to degrade to approximately 80 dB CMR (G = 1).
V+
0.1µF
49.4kΩ
G=1+
RG
DESIRED
GAIN (V/V)
RG
(Ω)
NEAREST
1% RG (Ω)
1
2
5
10
20
50
100
200
500
1000
2000
5000
10000
NC
49.4K
12.35K
5489
2600
1008
499
248
99
49.5
24.7
9.88
4.94
NC
49.9K
12.4K
5.49K
2.61K
1K
499
249
100
49.9
24.9
9.76
4.87
7
VIN-
2
Over Voltage
Protection
A1
40kΩ
1
VO = G · (VIN- - VIN+)
A3
RG
VIN
3
24.74kΩ
Over Voltage
Protection
A2
40kΩ
4
NC: No Connection
6
+
8
+
40kΩ
24.7kΩ
40kΩ
5
Ref
Load VO
-
0.1µF
V IN
V-
Also drawn in simplified form:
VO
RG
+
V IN
Ref
Figure 16. Basic Connections
8.2.1 Design Requirements
The device can be configured to monitor the input differential voltage when the gain of the input signal is set by
the external resistor RG. The output signal references to the REF pin. The most common application is where the
output is referenced to ground when no input signal is present by connecting the REF pin to ground, as
Figure 16 shows. When the input signal increases, the output voltage at the OUT pin increases, too.
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Typical Application (continued)
8.2.2 Detailed Design Procedure
8.2.2.1 Setting the Gain
Gain is set by connecting a single external resistor, RG, between pins 1 and 8.
49.4 kW
G=1+ ¾
RG
(1)
Commonly used gains and resistor values are shown in Figure 16.
The 49.9-kΩ term in Equation 1 comes from the sum of the two internal feedback resistors of A1 and A2. These
on-chip metal film resistors are laser trimmed to accurate absolute values. The accuracy and temperature
coefficient of these internal resistors are included in the gain accuracy and drift specifications of the INA129-EP.
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 Equation 1. Low resistor values required for high gain can
make wiring resistance important. Sockets add to the wiring resistance which will contribute additional gain error
(possibly an unstable gain error) in gains of approximately 100 or greater.
8.2.2.2 Dynamic Performance
Figure 1 shows that, despite its low quiescent current, the INA129-EP achieves wide bandwidth, even at high
gain. This is due to the current-feedback topology of the input stage circuitry. Settling time also remains excellent
at high gain.
8.2.2.3 Offset Trimming
The INA129-EP is laser trimmed for low offset voltage and offset voltage drift. Most applications require no
external offset adjustment. Figure 17 shows an optional circuit for trimming the output offset voltage. The voltage
applied to Ref terminal is summed with the output. The operational amplifier buffer provides low impedance at
the Ref terminal to preserve good common-mode rejection.
VIN
V+
RG
+
VIN
INA129
VO
100mA
1/2 REF200
Ref
OPA177
±10mV
Adjustment Range
10kW
100W
100W
100mA
1/2 REF200
V-
Figure 17. Optional Trimming of Output Offset Voltage
8.2.2.4 Input Bias Current Return Path
The input impedance of the INA129-EP is extremely high (approximately 1010 Ω). However, a path must be
provided for the input bias current of both inputs. This input bias current is approximately ±2 nA. 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 18 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, and the input amplifiers will saturate.
14
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Typical Application (continued)
If the differential source resistance is low, the bias current return path can be connected to one input (see the
thermocouple example in Figure 18). 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 highfrequency common-mode rejection.
Microphone,
Hydrophone
etc.
INA129
47kW
47kW
Thermocouple
INA129
10kW
INA129
Center-tap provides
bias current return.
Figure 18. Providing an Input Common-Mode Current Path
8.2.3 Application Curves
G=1
G = 10 0
20mV/div
20mV/div
G = 10
G = 10 0 0
20ms/div
5ms/div
G = 100, 1000
G = 1, 10
Figure 20. Small Signal
Figure 19. Small Signal
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Typical Application (continued)
G=1
G =100
5V/div
5V/div
G = 10
G =1000
5ms/div
20ms/div
G = 1, 10
G = 100, 1000
Figure 21. Large Signal
16
Figure 22. Large Signal
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9 Power Supply Recommendations
The minimum power supply voltage for INA129-EP is ±2.25 V and the maximum power supply voltage is ±18 V.
This minimum and maximum range covers a wide range of power supplies; but for optimum performance, ±15 V
is recommended. TI recommends adding a bypass capacitor at the input to compensate for the layout and power
supply source impedance.
9.1 Low Voltage Operation
The INA129-EP can be operated on power supplies as low as ±2.25 V. Performance remains excellent with
power supplies ranging from ±2.25 V to ±18 V. Most parameters vary only slightly throughout this supply voltage
range.
Operation at very low supply voltage requires careful attention to assure that the input voltages remain within
their linear range. Voltage swing requirements of internal nodes limit the input common-mode range with low
power supply voltage. Figure 5 and Figure 6 show the range of linear operation for ±15 V, ±5 V, and ±2.5 V
supplies.
+5V
2.5V - ∆V
VIN
+
RG
300W
RG
VO
INA129
Ref
VO
INA129
R1
1MW
C1
0.1mF
Ref
2.5V + ∆V
1
f-3dB=
2pR1C1
OPA130
= 1.59 Hz
Figure 23. Bridge Amplifier
Figure 24. AC-Coupled Instrumentation Amplifier
V+
10.0V
6
REF102
R1
VIN
2
IO =
R1
RG
INA129
V IN
· G
R1
+
Ref
R2
IB
4
A1
Pt100
Cu
K
VO
Cu
RG
INA129
E
J
K
T
MATERIAL
+Chromel
-Constantan
+Iron
-Constantan
+Chromel
-Alumel
+Copper
-Constantan
IB ERROR
OPA177
±1.5 nA
OPA131
±50 pA
OPA602
±1 pA
OPA128
±75 fA
IO
Load
Ref
R3
100Ω = Pt100 at 0°C
ISA
TYPE
A1
SEEBECK
COEFFICIENT
(mV/°C)
R1, R2
58.5
66.5kW
50.2
76.8kW
39.4
97.6kW
38
102kW
Figure 25. Thermocouple Amplifier With RTD ColdJunction Compensation
Figure 26. Differential Voltage to Current Converter
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Low Voltage Operation (continued)
RG = 5.6kW
2.8kW
G = 10
LA
RA
RG/2
INA129
VO
Ref
2.8kW
390kW
VG
1/2
OPA2131
RL
VG
1/2
OPA2131
10kW
390kW
NOTE: Due to the INA129’s current-feedback
topology, VG is approximately 0.7 V less than
the common-mode input voltage. This DC offset
in this guard potential is satisfactory for many
guarding applications.
Figure 27. ECG Amplifier With Right-Leg Drive
10 Layout
10.1 Layout Guidelines
Place the power-supply bypass capacitor as closely as possible to the supply and ground pins. The
recommended value of this bypass capacitor is 0.1 μF to 1 μF. If necessary, additional decoupling capacitance
can be added to compensate for noisy or high-impedance power supplies. These decoupling capacitors must be
placed between the power supply and INA129-EP device.
The gain resistor must be placed close to pin 1 and pin 8. This placement limits the layout loop and minimizes
any noise coupling into the part.
10.2 Layout Example
Gain Resistor
Bypass
Capacitor
VIN
VIN
–
+
R6
R6
V–IH
V+
V+IH
VO
V–
REF
V+
VOUT
GND
Bypass
Capacitor
V–
GND
Figure 28. Recommended Layout
18
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11 Device and Documentation Support
11.1 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
11.2 Trademarks
E2E is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
11.3 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
11.4 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
12 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
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19
PACKAGE OPTION ADDENDUM
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10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
INA129MDREP
ACTIVE
SOIC
D
8
2500
RoHS & Green
NIPDAU
Level-3-260C-168 HR
-55 to 125
129EP
V62/10605-01XE
ACTIVE
SOIC
D
8
2500
RoHS & Green
NIPDAU
Level-3-260C-168 HR
-55 to 125
129EP
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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