Sample &
Buy
Product
Folder
Support &
Community
Tools &
Software
Technical
Documents
INA333
SBOS445C – JULY 2008 – REVISED DECEMBER 2015
INA333 Micro-Power (50μA), Zerø-Drift, Rail-to-Rail Out Instrumentation Amplifier
1 Features
•
•
•
•
•
•
•
•
•
•
•
•
1
3 Description
The INA333 device is a low-power, precision
instrumentation amplifier offering excellent accuracy.
The versatile 3-operational amplifier design, small
size, and low power make it ideal for a wide range of
portable applications.
Low Offset Voltage: 25 μV (Maximum), G ≥ 100
Low Drift: 0.1 μV/°C, G ≥ 100
Low Noise: 50 nV/√Hz, G ≥ 100
High CMRR: 100 dB (Minimum), G ≥ 10
Low Input Bias Current: 200 pA (Maximum)
Supply Range: 1.8 V to 5.5 V
Input Voltage: (V–) +0.1 V to (V+) –0.1 V
Output Range: (V–) +0.05 V to (V+) –0.05 V
Low Quiescent Current: 50 μA
Operating Temperature: –40°C to +125°C
RFI Filtered Inputs
8-Pin VSSOP and 8-Pin WSON Packages
A single external resistor sets any gain from 1 to
1000. The INA333 is designed to use an industrystandard gain equation: G = 1 + (100 kΩ / RG).
The INA333 device provides very low offset voltage
(25 μV, G ≥ 100), excellent offset voltage drift
(0.1 μV/°C, G ≥ 100), and high common-mode
rejection (100 dB at G ≥ 10). It operates with power
supplies as low as 1.8 V (±0.9 V) and quiescent
current is only 50 μA, making it ideal for batteryoperated systems. Using autocalibration techniques
to ensure excellent precision over the extended
industrial temperature range, the INA333 device also
offers exceptionally low noise density (50 nV/√Hz)
that extends down to DC.
2 Applications
•
•
•
•
•
•
•
•
•
Bridge Amplifiers
ECG Amplifiers
Pressure Sensors
Medical Instrumentation
Portable Instrumentation
Weigh Scales
Thermocouple Amplifiers
RTD Sensor Amplifiers
Data Acquisition
The INA333 device is available in both 8-pin VSSOP
and WSON surface-mount packages and is specified
over the TA = –40°C to +125°C temperature range.
Device Information(1)
PART NUMBER
PACKAGE
INA333
BODY SIZE (NOM)
VSSOP (8)
3.00 mm × 3.00 mm
WSON (8)
3.00 mm × 3.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Simplified Schematic
V+
7
VIN-
2
RFI Filtered Inputs
150kW
150kW
A1
1
RFI Filtered Inputs
50kW
6
A3
RG
VOUT
50kW
8
RFI Filtered Inputs
VIN+
3
150kW
150kW
A2
5
REF
RFI Filtered Inputs
INA333
4
V-
G=1+
100kW
RG
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.
INA333
SBOS445C – JULY 2008 – 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
4
6.1
6.2
6.3
6.4
6.5
6.6
4
4
4
4
5
7
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information .................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description ............................................ 13
7.1 Overview ................................................................. 13
7.2 Functional Block Diagram ....................................... 13
7.3 Feature Description................................................. 13
7.4 Device Functional Modes........................................ 13
8
Application and Implementation ........................ 14
8.1 Application Information............................................ 14
8.2 Typical Application ................................................. 14
9 Power Supply Recommendations...................... 19
10 Layout................................................................... 20
10.1 Layout Guidelines ................................................. 20
10.2 Layout Example .................................................... 20
11 Device and Documentation Support ................. 21
11.1
11.2
11.3
11.4
11.5
Device Support......................................................
Documentation Support ........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
21
22
22
22
23
12 Mechanical, Packaging, and Orderable
Information ........................................................... 23
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision B (October 2008) to Revision C
•
2
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
Submit Documentation Feedback
Copyright © 2008–2015, Texas Instruments Incorporated
Product Folder Links: INA333
INA333
www.ti.com
SBOS445C – JULY 2008 – REVISED DECEMBER 2015
5 Pin Configuration and Functions
DGK Package
8-Pin VSSOP
Top View
DRG Package
8-Pin WSON
Top View
RG
1
8
RG
VIN-
2
7
V+
VIN+
3
6
VOUT
V-
4
5
REF
RG
1
VIN-
2
VIN+
3
V-
4
Exposed
Thermal
Die Pad
on
Underside
8
RG
7
V+
6
VOUT
5
REF
Pin Functions
PIN
NAME
NO.
I/O
DESCRIPTION
REF
5
I
RG
1, 8
—
Reference input. This pin must be driven by low impedance or connected to ground.
Gain setting pins. For gains greater than 1, place a gain resistor between pins 1 and 8.
V+
7
—
Positive supply
–
V
4
—
Negative supply
VIN+
3
I
Positive input
VIN–
2
I
Negative input
VOUT
6
O
Output
Submit Documentation Feedback
Copyright © 2008–2015, Texas Instruments Incorporated
Product Folder Links: INA333
3
INA333
SBOS445C – JULY 2008 – REVISED DECEMBER 2015
www.ti.com
6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)
(1)
MIN
Supply voltage
MAX
Analog input voltage
(2)
V
(V–) – 0.3
Output short-circuit (3)
(V+) + 0.3
–40
Junction temperature, TJ
Storage temperature, Tstg
(2)
(3)
V
Continuous
Operating temperature, TA
(1)
UNIT
7
–65
150
°C
150
°C
150
°C
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
Input pins are diode-clamped to the power-supply rails. Input signals that can swing more than 0.3 V beyond the supply rails should be
current limited to 10 mA or less.
Short-circuit to ground.
6.2 ESD Ratings
VALUE
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001
V(ESD)
(1)
(2)
Electrostatic discharge
(1)
UNIT
±4000
Charged-device model (CDM), per JEDEC specification JESD22-C101 (2)
±1000
Machine model (MM)
±200
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)
MIN
VS
MAX
UNIT
Supply voltage
1.8
5.5
V
Specified temperature
–40
125
°C
6.4 Thermal Information
INA333
THERMAL METRIC (1)
DGK (VSSOP)
DRG (WSON)
UNIT
8 PINS
8 PINS
RθJA
Junction-to-ambient thermal resistance
169.5
60
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
62.7
60
°C/W
RθJB
Junction-to-board thermal resistance
90.3
50
°C/W
ψJT
Junction-to-top characterization parameter
7.6
—
°C/W
ψJB
Junction-to-board characterization parameter
88.7
—
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
—
6
°C/W
(1)
4
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953.
Submit Documentation Feedback
Copyright © 2008–2015, Texas Instruments Incorporated
Product Folder Links: INA333
INA333
www.ti.com
SBOS445C – JULY 2008 – REVISED DECEMBER 2015
6.5 Electrical Characteristics
for VS = 1.8 V to 5.5 V at TA = 25°C, RL = 10 kΩ, VREF = VS / 2, and G = 1 (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
INPUT (1)
Offset voltage, RTI (2)
VOSI
PSR
±10 ±25/G
vs temperature
TA = –40°C to +125°C
vs power supply
1.8 V ≤ VS ≤ 5.5 V
±1 ±5/G
Long-term stability
Turnon time to specified VOSI
See
TA = –40°C to +125°C
μV
±25 ±75/G
±0.1 ±0.5 / G
μV/°C
±5 ±15/G
μV/V
(3)
See Typical Characteristics
Impedance
ZIN
Differential
100 || 3
ZIN
Common-mode
100 || 3
VCM
Common-mode voltage range
VO = 0 V
Common-mode rejection
DC to 60 Hz
G=1
VCM = (V–) + 0.1 V
to (V+) – 0.1 V
80
90
dB
G = 10
VCM = (V–) + 0.1 V
to (V+) – 0.1 V
100
110
dB
G = 100
VCM = (V–) + 0.1 V
to (V+) – 0.1 V
100
115
dB
G = 1000
VCM = (V–) + 0.1 V
to (V+) – 0.1 V
100
115
dB
CMR
(V–) + 0.1
GΩ || pF
GΩ || pF
(V+) – 0.1
V
INPUT BIAS CURRENT
Input bias current
IB
vs temperature
±70
TA = –40°C to +125°C
See Figure 26
TA = –40°C to +125°C
See Figure 28
Input offset current
IOS
vs temperature
±200
pA
pA/°C
±50
±200
pA
pA/°C
INPUT VOLTAGE NOISE
eNI
Input voltage noise
G = 100, RS = 0 Ω, f = 10 Hz
50
nV/√Hz
G = 100, RS = 0 Ω, f = 100 Hz
50
nV/√Hz
G = 100, RS = 0 Ω, f = 1 kHz
50
nV/√Hz
G = 100, RS = 0 Ω, f = 0.1 Hz to 10 Hz
iN
Input current noise
μVPP
1
f = 10 Hz
100
f = 0.1 Hz to 10 Hz
fA/√Hz
2
pAPP
GAIN
G
Gain equation
1 + (100 kΩ/RG)
Range of gain
1
V/V
1000
V/V
VS = 5.5 V, (V–) + 100 mV
≤ VO ≤ (V+) – 100 mV
Gain error
G=1
±0.01%
±0.1%
G = 10
±0.05%
±0.25%
G = 100
±0.07%
±0.25%
G = 1000
±0.25%
±0.5%
Gain vs temperature, G = 1
TA = –40°C to +125°C
±1
±5
ppm/°C
Gain vs temperature, G > 1 (4)
TA = –40°C to +125°C
±15
±50
ppm/°C
Gain nonlinearity
VS = 5.5 V, (V–) + 100 mV
≤ VO ≤ (V+) – 100 mV
Gain nonlinearity, G = 1 to 1000
RL = 10 kΩ
Output voltage swing from rail
VS = 5.5 V, RL = 10 kΩ
10
ppm
OUTPUT
Capacitive load drive
ISC
(1)
(2)
(3)
(4)
Short-circuit current
Continuous to common
See Figure 29
50
mV
500
pF
–40, +5
mA
Total VOS, referred-to-input = (VOSI) + (VOSO / G)
RTI = Referred-to-input
300-hour life test at 150°C demonstrated randomly distributed variation of approximately 1 μV
Does not include effects of external resistor RG
Submit Documentation Feedback
Copyright © 2008–2015, Texas Instruments Incorporated
Product Folder Links: INA333
5
INA333
SBOS445C – JULY 2008 – REVISED DECEMBER 2015
www.ti.com
Electrical Characteristics (continued)
for VS = 1.8 V to 5.5 V at TA = 25°C, RL = 10 kΩ, VREF = VS / 2, and G = 1 (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
FREQUENCY RESPONSE
Bandwidth, –3dB
SR
tS
tS
Slew rate
Settling time to 0.01%
Settling time to 0.001%
Overload recovery
G=1
150
kHz
G = 10
35
kHz
G = 100
3.5
kHz
G = 1000
350
Hz
VS = 5 V, VO = 4-V step, G = 1
0.16
V/μs
VS = 5 V, VO = 4-V step, G = 100
0.05
V/μs
VSTEP = 4 V, G = 1
VSTEP = 4 V, G = 100
VSTEP = 4 V, G = 1
VSTEP = 4 V, G = 100
50% overdrive
50
μs
400
μs
60
μs
500
μs
75
μs
REFERENCE INPUT
RIN
300
Voltage range
V–
kΩ
V+
V
V
POWER SUPPLY
Voltage range
IQ
Single voltage range
+1.8
+5.5
Dual voltage range
±0.9
±2.75
V
75
μA
80
μA
Quiescent current
VIN = VS / 2
50
vs temperature
TA = –40°C to +125°C
TEMPERATURE RANGE
6
Specified temperature range
–40
125
°C
Operating temperature range
–40
150
°C
Submit Documentation Feedback
Copyright © 2008–2015, Texas Instruments Incorporated
Product Folder Links: INA333
INA333
www.ti.com
SBOS445C – JULY 2008 – REVISED DECEMBER 2015
6.6 Typical Characteristics
at TA = 25°C, VS = 5 V, RL = 10 kΩ, VREF = midsupply, and G = 1 (unless otherwise noted)
VS = 5.5V
-25.0
-22.5
-20.0
-17.5
-15.0
-12.5
-10.0
-7.5
-5.0
-2.5
0
2.5
5.0
7.5
10.0
12.5
15.0
17.5
20.0
22.5
25.0
-0.10
-0.09
-0.08
-0.07
-0.06
-0.05
-0.04
-0.03
-0.02
-0.01
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.10
Population
Population
VS = 5.5V
Input Offset Voltage (mV)
Input Voltage Offset Drift (mV/°C)
Figure 2. Input Voltage Offset Drift (–40°C to 125°C)
Figure 1. Input Offset Voltage
VS = 5.5V
-75.0
-67.5
-60.0
-52.5
-45.0
-37.5
-30.0
-22.5
-15.0
-7.5
0
7.5
15.0
22.5
30.0
37.5
45.0
52.5
60.0
67.5
75.0
-0.50
-0.45
-0.40
-0.35
-0.30
-0.25
-0.20
-0.15
-0.10
-0.05
0
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
Population
Population
VS = 5.5V
Output Offset Voltage (mV)
Output Voltage Offset Drift (mV/°C)
Figure 4. Output Voltage Offset Drift (–40°C to 125°C)
Figure 3. Output Offset Voltage
0
Gain = 1
VS = 1.8V
-5
Noise (1mV/div)
VOS (mV)
VS = 5V
-10
-15
-20
-25
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Time (1s/div)
VCM (V)
Figure 5. Offset Voltage vs Common-Mode Voltage
Figure 6. 0.1-Hz to 10-Hz Noise
Submit Documentation Feedback
Copyright © 2008–2015, Texas Instruments Incorporated
Product Folder Links: INA333
7
INA333
SBOS445C – JULY 2008 – REVISED DECEMBER 2015
www.ti.com
Typical Characteristics (continued)
at TA = 25°C, VS = 5 V, RL = 10 kΩ, VREF = midsupply, and G = 1 (unless otherwise noted)
1000
Noise (0.5mV/div)
1000
Output Noise
100
100
Current Noise
Input Noise
10
10
2
(Input Noise) +
Total Input-Referred Noise =
(Output Noise)
2
G
1
1
0.1
Time (1s/div)
Current Noise Density (fA/ÖHz)
Voltage Noise Density (nV/ÖHz)
Gain = 100
1
10
100
1k
10k
Frequency (Hz)
Figure 8. Spectral Noise Density
Figure 7. 0.1-Hz to 10-Hz Noise
G = 1000
G = 100
G = 10
G=1
0.008
Gain = 1
VS = ±2.75V
Output Voltage (1V/div)
DC Output Nonlinearity Error (%FSR)
0.012
0.004
0
-0.004
-0.008
-0.012
0
0.5
1.0
1.5
2.0
2.5
3.0 3.5
4.0
4.5
5.0
5.5
Time (25ms/div)
VOUT (V)
Figure 9. Nonlinearity Error
Figure 10. Large Signal Response
Gain = 1
Output Voltage (1V/div)
Output Voltage (50mV/div)
Gain = 100
Time (100ms/div)
Time (10ms/div)
Figure 11. Large-Signal Step Response
8
Submit Documentation Feedback
Figure 12. Small-Signal Step Response
Copyright © 2008–2015, Texas Instruments Incorporated
Product Folder Links: INA333
INA333
www.ti.com
SBOS445C – JULY 2008 – REVISED DECEMBER 2015
Typical Characteristics (continued)
at TA = 25°C, VS = 5 V, RL = 10 kΩ, VREF = midsupply, and G = 1 (unless otherwise noted)
10000
Output Voltage (50mV/div)
Gain = 100
Time (ms)
1000
0.001%
100
0.01%
0.1%
10
1
Time (100ms/div)
1000
100
10
Gain (V/V)
Figure 14. Settling Time vs Gain
Figure 13. Small-Signal Step Response
80
Gain = 1
G = 1000
Supply
60
40
Gain (dB)
Supply (1V/div)
VOUT (50mV/div)
VOUT
G = 100
G = 10
20
G=1
0
-20
-40
-60
10
Time (50ms/div)
100
10k
1k
100k
1M
Frequency (Hz)
Figure 16. Gain vs Frequency
Figure 15. Start-Up Settling Time
10
VS = 5.5V
VS = ±2.75V
8
G=1
VS = ±0.9V
Population
CMRR (mV/V)
6
4
G = 10
2
0
-2
-4
G = 100,
G = 1000
-6
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
-8
-10
-50
-25
0
25
50
75
100
125
150
Temperature (°C)
CMRR (mV/V)
Figure 17. Common-Mode Rejection Ratio
Figure 18. Common-Mode Rejection Ratio vs Temperature
Submit Documentation Feedback
Copyright © 2008–2015, Texas Instruments Incorporated
Product Folder Links: INA333
9
INA333
SBOS445C – JULY 2008 – REVISED DECEMBER 2015
www.ti.com
Typical Characteristics (continued)
at TA = 25°C, VS = 5 V, RL = 10 kΩ, VREF = midsupply, and G = 1 (unless otherwise noted)
2.5
140
2.0
Common-Mode Voltage (V)
160
G = 1000
CMRR (dB)
120
G = 100
100
80
60
G=1
40
G = 10
20
VS = ±2.5V
VREF = 0
1.0
All Gains
0
-1.0
-2.0
2.5
-2.5 -2.0
0
10
100k
10k
1k
100
2.0
1.0
2.5
Output Voltage (V)
Figure 19. Common-Mode Rejection Ratio vs Frequency
5
Figure 20. Typical Common-Mode Range vs Output Voltage
0.9
VS = +5V
VREF = 0
VS = ±0.9V
VREF = 0
0.7
Common-Mode Voltage (V)
Common-Mode Voltage (V)
0
-1.0
Frequency (Hz)
4
3
All Gains
2
1
0.5
0.3
0.1
All Gains
-0.1
-0.3
-0.5
-0.7
-0.9
-0.9
0
0
3
2
1
5
4
-0.7
Output Voltage (V)
140
1.4
0.5
0.7
0.9
G = 1000
120
1.2
1.0
+PSRR (dB)
Common-Mode Voltage (V)
0.3
160
All Gains
0.8
0.6
100
G = 100
80
60
G = 10
40
0.4
G=1
20
0.2
0
0
0
10
0.1
-0.1
Figure 22. Typical Common-Mode Range vs Output Voltage
VS = +1.8V
VREF = 0
1.6
-0.3
Output Voltage (V)
Figure 21. Typical Common-Mode Range vs Output Voltage
1.8
-0.5
0.2
0.4
0.5
0.8
1.0
1.2
1.4
1.6
1.8
1
10
100
1k
10k
100k
1M
Output Voltage (V)
Frequency (Hz)
Figure 23. Typical Common-Mode Range vs Output Voltage
Figure 24. Positive Power-Supply Rejection Ratio
Submit Documentation Feedback
Copyright © 2008–2015, Texas Instruments Incorporated
Product Folder Links: INA333
INA333
www.ti.com
SBOS445C – JULY 2008 – REVISED DECEMBER 2015
Typical Characteristics (continued)
at TA = 25°C, VS = 5 V, RL = 10 kΩ, VREF = midsupply, and G = 1 (unless otherwise noted)
160
1200
VS = 5V
140
G = 100
G = 1000
-IB
800
100
600
IB (pA)
-PSRR (dB)
120
80
+IB
1000
G = 10
60
400
VS = ±0.9V
40
VS = ±2.75V
200
G=1
20
0
0
-20
-200
0.1
10
1
100
1k
10k
100k
1M
-50
25
0
-25
Frequency (Hz)
50
75
100
125
150
Temperature (°C)
Figure 25. Negative Power-Supply Rejection Ratio
Figure 26. Input Bias Current vs Temperature
200
250
180
200
160
150
120
IOS (pA)
| IB | (pA)
140
100
80
60
100
VS = ±2.75V
50
0
VS = 5V
40
VS = ±0.9V
-50
20
VS = 1.8V
0
0
0.5
1.0
1.5
2.0
-100
2.5
3.0
3.5
4.0
4.5
5.0
-50
-25
0
VCM (V)
50
75
100
125
150
Temperature (°C)
Figure 27. Input Bias Current vs Common-Mode Voltage
Figure 28. Input Offset Current vs Temperature
80
(V+)
(V+) - 0.25
(V+) - 0.50
(V+) - 0.75
(V+) - 1.00
(V+) - 1.25
(V+) - 1.50
(V+) - 1.75
VS = ±2.75V
70
VS = ±0.9V
VS = 5V
60
50
IQ (mA)
VOUT (V)
25
(V-) + 1.75
(V-) + 1.50
(V-) + 1.25
(V-) + 1.00
(V-) + 0.75
(V-) + 0.50
(V-) + 0.25
(V-)
40
VS = 1.8V
30
20
+125°C
+25°C
-40°C
10
0
0
10
20
30
40
50
60
-50
IOUT (mA)
-25
0
25
50
75
100
125
150
Temperature (°C)
Figure 29. Output Voltage Swing vs Output Current
Figure 30. Quiescent Current vs Temperature
Submit Documentation Feedback
Copyright © 2008–2015, Texas Instruments Incorporated
Product Folder Links: INA333
11
INA333
SBOS445C – JULY 2008 – REVISED DECEMBER 2015
www.ti.com
Typical Characteristics (continued)
at TA = 25°C, VS = 5 V, RL = 10 kΩ, VREF = midsupply, and G = 1 (unless otherwise noted)
80
70
VS = 5V
60
IQ (mA)
50
40
VS = 1.8V
30
20
10
0
0
1.0
3.0
2.0
4.0
5.0
VCM (V)
Figure 31. Quiescent Current vs Common-Mode Voltage
12
Submit Documentation Feedback
Copyright © 2008–2015, Texas Instruments Incorporated
Product Folder Links: INA333
INA333
www.ti.com
SBOS445C – JULY 2008 – REVISED DECEMBER 2015
7 Detailed Description
7.1 Overview
The INA333 is a monolithic instrumentation amplifier (INA) based on the precision zero-drift OPA333 (operational
amplifier) core. The INA333 also integrates laser-trimmed resistors to ensure excellent common-mode rejection
and low gain error. The combination of the zero-drift amplifier core and the precision resistors allows this device
to achieve outstanding DC precision and makes the INA333 ideal for many 3.3-V and 5-V industrial applications.
7.2 Functional Block Diagram
V+
7
VIN-
2
RFI Filtered Inputs
150kW
150kW
A1
1
RFI Filtered Inputs
50kW
6
A3
RG
VOUT
50kW
8
RFI Filtered Inputs
VIN+
3
150kW
150kW
A2
5
REF
RFI Filtered Inputs
INA333
4
V-
G=1+
100kW
RG
7.3 Feature Description
The INA333 is a low-power, zero-drift instrumentation amplifier offering excellent accuracy. The versatile threeoperational-amplifier design and small size make the amplifiers ideal for a wide range of applications. Zero-drift
chopper circuitry provides excellent DC specifications. A single external resistor sets any gain from 1 to 10,000.
The INA333 is laser trimmed for very high common-mode rejection (100 dB at G ≥ 100). This devices operate
with power supplies as low as 1.8 V, and quiescent current of 50 µA, typically.
7.4 Device Functional Modes
7.4.1 Internal Offset Correction
INA333 internal operational amplifiers use an auto-calibration technique with a time-continuous 350-kHz
operational amplifier in the signal path. The amplifier is zero-corrected every 8 µs using a proprietary technique.
Upon power up, the amplifier requires approximately 100 µs to achieve specified VOS accuracy. This design has
no aliasing or flicker noise.
7.4.2 Input Common-Mode Range
The linear input voltage range of the input circuitry of the INA333 is from approximately 0.1 V below the positive
supply voltage to 0.1 V above the negative supply. As a differential input voltage causes the output voltage to
increase, however, the linear input range is limited by the output voltage swing of amplifiers A1 and A2. Thus, 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 20.
Input overload conditions can produce an output voltage that appears normal. For example, if an input overload
condition drives both input amplifiers to the respective positive output swing limit, the difference voltage
measured by the output amplifier is near zero. The output of the INA333 is near 0 V even though both inputs are
overloaded.
Submit Documentation Feedback
Copyright © 2008–2015, Texas Instruments Incorporated
Product Folder Links: INA333
13
INA333
SBOS445C – JULY 2008 – REVISED DECEMBER 2015
www.ti.com
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 INA333 measures small differential voltage with high common-mode voltage developed between the
noninverting and inverting input. The high input impedance makes the INA333 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 32 shows the basic connections required for operation of the INA333 device. Good layout practice
mandates the use of bypass capacitors placed close to the device pins as shown.
The output of the INA333 device is referred to the output reference (REF) pin, which is normally grounded. This
connection must be low-impedance to assure good common-mode rejection. Although 15 Ω or less of stray
resistance can be tolerated while maintaining specified CMRR, small stray resistances of tens of Ωs in series
with the REF pin can cause noticeable degradation in CMRR.
V+
0.1mF
7
VIN-
2
RFI Filter
150kW
150kW
A1
VO = G ´ (VIN+ - VIN-)
RFI Filter
1
50kW
RG
G=1+
6
A3
50kW
+
8
Load VO
RFI Filter
VIN+
100kW
RG
150kW
-
150kW
5
A2
3
Ref
RFI Filter
INA333
4
0.1mF
V-
Also drawn in simplified form:
VINRG
VIN+
VO
INA333
Ref
Figure 32. Basic Connections
14
Submit Documentation Feedback
Copyright © 2008–2015, Texas Instruments Incorporated
Product Folder Links: INA333
INA333
www.ti.com
SBOS445C – JULY 2008 – REVISED DECEMBER 2015
Typical Application (continued)
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. When the
input signal increases, the output voltage at the OUT pin increases, too.
8.2.2 Detailed Design Procedure
8.2.2.1 Setting the Gain
Gain of the INA333 device is set by a single external resistor, RG, connected between pins 1 and 8. The value of
RG is selected according to Equation 1:
G = 1 + (100 kΩ / RG)
(1)
Table 1 lists several commonly-used gains and resistor values. The 100 kΩ in Equation 1 comes from the sum of
the two internal feedback resistors of A1 and A2. These on-chip resistors are laser trimmed to accurate absolute
values. The accuracy and temperature coefficient of these resistors are included in the gain accuracy and drift
specifications of the INA333 device.
The stability and temperature drift of the external gain setting resistor, RG, also affects gain. The contribution of
RG to gain accuracy and drift can be directly inferred from the gain Equation 1. Low resistor values required for
high gain can make wiring resistance important. Sockets add to the wiring resistance and contribute additional
gain error (possibly an unstable gain error) in gains of approximately 100 or greater. To ensure stability, avoid
parasitic capacitance of more than a few picofarads at the RG connections. Careful matching of any parasitics on
both RG pins maintains optimal CMRR over frequency.
Table 1. Commonly-Used Gains and Resistor Values
DESIRED GAIN
(1)
RG (Ω)
(1)
NEAREST 1% RG (Ω)
1
NC
2
100k
100k
NC
5
25k
24.9k
10
11.1k
11k
20
5.26k
5.23k
50
2.04k
2.05
100
1.01k
1k
200
502.5
499
500
200.4
200
1000
100.1
100
NC denotes no connection. When using the SPICE model, the simulation will not converge unless a
resistor is connected to the RG pins; use a very large resistor value.
8.2.2.2 Internal Offset Correction
The INA333 device internal operational amplifiers use an auto-calibration technique with a time-continuous 350kHz operational amplifier in the signal path. The amplifier is zero-corrected every 8 μs using a proprietary
technique. Upon power-up, the amplifier requires approximately 100 μs to achieve specified VOS accuracy. This
design has no aliasing or flicker noise.
8.2.2.3 Offset Trimming
Most applications require no external offset adjustment; however, if necessary, adjustments can be made by
applying a voltage to the REF pin. Figure 33 shows an optional circuit for trimming the output offset voltage. The
voltage applied to REF pin is summed at the output. The operational amplifier buffer provides low impedance at
the REF pin to preserve good common-mode rejection.
Submit Documentation Feedback
Copyright © 2008–2015, Texas Instruments Incorporated
Product Folder Links: INA333
15
INA333
SBOS445C – JULY 2008 – REVISED DECEMBER 2015
www.ti.com
VIN-
V+
RG
VO
INA333
100mA
1/2 REF200
Ref
VIN+
100W
OPA333
±10mV
Adjustment Range
10kW
100W
100mA
1/2 REF200
V-
Figure 33. Optional Trimming of Output Offset Voltage
8.2.2.4 Noise Performance
The auto-calibration technique used by the INA333 device results in reduced low frequency noise, typically only
50 nV/√Hz, (G = 100). The spectral noise density can be seen in detail in Figure 8. Low frequency noise of the
INA333 device is approximately 1 μVPP measured from 0.1 Hz to 10 Hz, (G = 100).
8.2.2.5 Input Bias Current Return Path
The input impedance of the INA333 device is extremely high—approximately 100 GΩ. However, a path must be
provided for the input bias current of both inputs. This input bias current is typically ±70 pA. 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 34 shows various
provisions for an input bias current path. Without a bias current path, the inputs float to a potential that exceeds
the common-mode range of the INA333 device, 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 thermocouple example in
Figure 34). With higher source impedance, using two equal resistors provides a balanced input with possible
advantages of lower input offset voltage as a result of bias current and better high-frequency common-mode
rejection.
16
Submit Documentation Feedback
Copyright © 2008–2015, Texas Instruments Incorporated
Product Folder Links: INA333
INA333
www.ti.com
SBOS445C – JULY 2008 – REVISED DECEMBER 2015
Microphone,
Hydrophone,
etc.
INA333
47kW
47kW
Thermocouple
INA333
10kW
INA333
Center tap provides
bias current return.
Figure 34. Providing an Input Common-Mode Current Path
8.2.2.6 Input Common-Mode Range
The linear input voltage range of the input circuitry of the INA333 device is from approximately 0.1 V below the
positive supply voltage to 0.1 V above the negative supply. As a differential input voltage causes the output
voltage to increase, however, the linear input range is limited by the output voltage swing of amplifiers A1 and A2.
Thus, 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 20 to Figure 23 in the Typical Characteristics section.
Input overload conditions can produce an output voltage that appears normal. For example, if an input overload
condition drives both input amplifiers to the respective positive output swing limit, the difference voltage
measured by the output amplifier is near zero. The output of the INA333 is near 0 V even though both inputs are
overloaded.
8.2.2.7 Operating Voltage
The INA333 operates over a power-supply range of 1.8 V to 5.5 V (±0.9 V to ±2.75 V). Supply voltages higher
than 7 V (absolute maximum) can permanently damage the device. Parameters that vary over supply voltage or
temperature are shown in the Typical Characteristics section of this data sheet.
8.2.2.8 Low Voltage Operation
The INA333 device can be operated on power supplies as low as ±0.9 V. Most parameters vary only slightly
throughout this supply voltage range—see the Typical Characteristics section. Operation at very low supply
voltage requires careful attention to assure that the input voltages remain within the linear range. Voltage swing
requirements of internal nodes limit the input common-mode range with low power-supply voltage. Figure 20 to
Figure 23 show the range of linear operation for various supply voltages and gains.
8.2.2.9 Single-Supply Operation
The INA333 device can be used on single power supplies of 1.8 V to 5.5 V. Figure 35 shows a basic singlesupply circuit. The output REF pin is connected to mid-supply. Zero differential input voltage demands an output
voltage of mid-supply. Actual output voltage swing is limited to approximately 50 mV more than ground, when the
load is referred to ground as shown. Figure 29 shows how the output voltage swing varies with output current.
Submit Documentation Feedback
Copyright © 2008–2015, Texas Instruments Incorporated
Product Folder Links: INA333
17
INA333
SBOS445C – JULY 2008 – REVISED DECEMBER 2015
www.ti.com
With single-supply operation, VIN+ and VIN– must both be 0.1 V more than ground for linear operation. For
instance, the inverting input cannot be connected to ground to measure a voltage connected to the noninverting
input.
To show the issues affecting low voltage operation, consider the circuit in Figure 35. It shows the INA333 device
operating from a single 3-V supply. A resistor in series with the low side of the bridge assures that the bridge
output voltage is within the common-mode range of the amplifier inputs.
+3V
3V
2V - DV
RG
300W
VO
INA333
Ref
2V + DV
1.5V
150W
R1
(1)
(1)
R1 creates proper common-mode voltage, only for low-voltage operation—see Single-Supply Operation.
Figure 35. Single-Supply Bridge Amplifier
8.2.2.10 Input Protection
The input pins of the INA333 device are protected with internal diodes connected to the power-supply rails.
These diodes clamp the applied signal to prevent it from damaging the input circuitry. If the input signal voltage
can exceed the power supplies by more than 0.3 V, the input signal current should be limited to less than 10 mA
to protect the internal clamp diodes. This current limiting can generally be done with a series input resistor. Some
signal sources are inherently current-limited and do not require limiting resistors.
18
Submit Documentation Feedback
Copyright © 2008–2015, Texas Instruments Incorporated
Product Folder Links: INA333
INA333
www.ti.com
SBOS445C – JULY 2008 – REVISED DECEMBER 2015
8.2.3 Application Curves
Output Voltage (1V/div)
Gain = 100
Output Voltage (1V/div)
Gain = 1
Time (25ms/div)
Time (100ms/div)
Figure 36. Large Signal Response
Figure 37. Large-Signal Step Response
Output Voltage (50mV/div)
Gain = 100
Output Voltage (50mV/div)
Gain = 1
Time (10ms/div)
Time (100ms/div)
Figure 38. Small-Signal Step Response
Figure 39. Small-Signal Step Response
9 Power Supply Recommendations
The minimum power supply voltage for INA333 is 1.8 V and the maximum power supply voltage is 5.5 V. For
optimum performance, 3.3 V to 5 V is recommended. TI recommends adding a bypass capacitor at the input to
compensate for the layout and power supply source impedance.
Submit Documentation Feedback
Copyright © 2008–2015, Texas Instruments Incorporated
Product Folder Links: INA333
19
INA333
SBOS445C – JULY 2008 – REVISED DECEMBER 2015
www.ti.com
10 Layout
10.1 Layout Guidelines
Attention to good layout practices is always recommended. Keep traces short and, when possible, use a printedcircuit-board (PCB) ground plane with surface-mount components placed as close to the device pins as possible.
Place a 0.1-μF bypass capacitor closely across the supply pins. These guidelines should be applied throughout
the analog circuit to improve performance and provide benefits such as reducing the electromagneticinterference (EMI) susceptibility.
Instrumentation amplifiers vary in the susceptibility to radio-frequency interference (RFI). RFI can generally be
identified as a variation in offset voltage or DC signal levels with changes in the interfering RF signal. The
INA333 device has been specifically designed to minimize susceptibility to RFI by incorporating passive RC
filters with an 8-MHz corner frequency at the VIN+ and VIN– inputs. As a result, the INA333 device demonstrates
remarkably low sensitivity compared to previous generation devices. Strong RF fields may continue to cause
varying offset levels, however, and may require additional shielding.
10.2 Layout Example
Gain Resistor
Bypass
Capacitor
RG
RG
VIN-
V-IN
V+
VIN+
V+IN
VO
VOUT
V-
Ref
GND
V+
Bypass
Capacitor
V-
GND
Figure 40. INA333 Layout
20
Submit Documentation Feedback
Copyright © 2008–2015, Texas Instruments Incorporated
Product Folder Links: INA333
INA333
www.ti.com
SBOS445C – JULY 2008 – REVISED DECEMBER 2015
11 Device and Documentation Support
11.1 Device Support
11.1.1 Development Support
11.1.1.1 TINA-TI (Free Download Software)
Using TINA-TI SPICE-Based Analog Simulation Program with the INA333
TINA is a simple, powerful, and easy-to-use circuit simulation program based on a SPICE engine. TINA-TI is a
free, fully functional version of the TINA software, preloaded with a library of macromodels in addition to a range
of both passive and active models. It provides all the conventional DC, transient, and frequency domain analysis
of SPICE as well as additional design capabilities.
Available as a free download from the Analog eLab Design Center, TINA-TI offers extensive post-processing
capability that allows users to format results in a variety of ways.
Virtual instruments offer users the ability to select input waveforms and probe circuit nodes, voltages, and
waveforms, creating a dynamic quick-start tool.
Figure 41 and Figure 42 show example TINA-TI circuits for the INA333 device that can be used to develop,
modify, and assess the circuit design for specific applications. Links to download these simulation files are given
below.
NOTE
These files require that either the TINA software (from DesignSoft) or TINA-TI software be
installed. Download the free TINA-TI software from the TINA-TI folder.
VoA1
1/2 of matched
monolithic dual
NPN transistors
(example: MMDT3904)
RELATED PRODUCTS
For monolithic logarithmic amplifiers (such as LOG112 or LOG114) see the link in footnote 1.
Vout
+
V
4
5
VM1
8
3
6
+
5
+
7
VCC
VCC
Ref
RG V+
U5 OPA369
Vdiff
Vref+
1/2 of matched
monolithic dual
NPN transistors
(example: MMDT3904)
-
R8 10k
Out
+
U1 OPA335
VCC
+
1
U1 INA333
Optional buffer for driving
SAR converters with
sampling systems of ³ 33kHz.
VCC
1
Vref+
Vref+
Input I 10n
+
4
RG V-
C1 1n
-
_
Vref+
2
R3 14k
2
3
VoA2
3
Vref+
uC Vref/2 2.5
1
+
uC Vref/2 2.5
2
+
4
5
V1 5
NOTE: Temperature compensation
of logging transistors is not shown.
U6 OPA369
VCC
Rset 2.5M
(1) The following link launches the TI logarithmic amplifiers web page: Logarithmic Amplifier Products Home Page
Figure 41. Low-Power Log Function Circuit for Portable Battery-Powered Systems
(Example Glucose Meter)
Submit Documentation Feedback
Copyright © 2008–2015, Texas Instruments Incorporated
Product Folder Links: INA333
21
INA333
SBOS445C – JULY 2008 – REVISED DECEMBER 2015
www.ti.com
Device Support (continued)
To download a compressed file that contains the TINA-TI simulation file for this circuit, click the following link:
Log Circuit.
3V
R1
2kW
RWa
3W
EMU21 RTD3
-
Pt100 RTD
VT+
U2
OPA333
RWb
3W
+
RTD+
VT 25
+
2 _
3V
VT-
RTD-
Mon+
RGAIN
100kW
Mon-
+
4
U1 INA333
RG V-
VDIFF
Out
Ref
8
RG V+
RWc
4W
Temp (°C)
(Volts = °C)
1
RZERO
100W
3
PGA112
MSP430
6
5
+
7
V
VREF+
3V
VRTD
RWd
3W
RTD Resistance
(Volts = Ohms)
+
+
A
IREF1
A
IREF2
3V
U1 REF3212
VREF
3V
VREF
VREF
Use BF861A
EN
+
In
OUTS
GNDF GNDS
C7
470nF
S
OUTF
+
T3 BF256A
OPA3331 OPA333
Use BF861A
3V
T1 BF256A
+
+
U3
OPA333
3V
-
G
-
V4 3
RSET1
2.5kW
RSET2
2.5kW
RWa, RWb, RWc, and RWd simulate wire resistance. These resistors are included to show the four-wire sense technique immunity to line
mismatches. This method assumes the use of a four-wire RTD.
Figure 42. Four-Wire, 3-V Conditioner for a PT100 RTD With Programmable Gain Acquisition System
To download a compressed file that contains the TINA-TI simulation file for this circuit, click the following link:
PT100 RTD.
11.2 Documentation Support
11.2.1 Related Documentation
For related documentation see the following:
• Precision, Low-Noise, Rail-to-Rail Output, 36-V, Zero-Drift Operational Amplifiers, SBOS642
• 50μV VOS, 0.25μV/°C, 35μA CMOS OPERATIONAL AMPLIFIERS Zerø-Drift Series, SBOS432
• 4ppm/°C, 100μA, SOT23-6 SERIES VOLTAGE REFERENCE, SBVS058
• Circuit Board Layout Techniques, SLOA089
11.3 Trademarks
All trademarks are the property of their respective owners.
11.4 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.
22
Submit Documentation Feedback
Copyright © 2008–2015, Texas Instruments Incorporated
Product Folder Links: INA333
INA333
www.ti.com
SBOS445C – JULY 2008 – REVISED DECEMBER 2015
11.5 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.
Submit Documentation Feedback
Copyright © 2008–2015, Texas Instruments Incorporated
Product Folder Links: INA333
23
PACKAGE OPTION ADDENDUM
www.ti.com
6-Feb-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
Op Temp (°C)
Device Marking
(4/5)
INA333AIDGKR
ACTIVE
VSSOP
DGK
8
2500
Green (RoHS
& no Sb/Br)
NIPDAU | NIPDAUAG
Level-2-260C-1 YEAR
-40 to 125
I333
INA333AIDGKRG4
ACTIVE
VSSOP
DGK
8
2500
Green (RoHS
& no Sb/Br)
NIPDAUAG
Level-2-260C-1 YEAR
-40 to 125
I333
INA333AIDGKT
ACTIVE
VSSOP
DGK
8
250
Green (RoHS
& no Sb/Br)
NIPDAU | NIPDAUAG
Level-2-260C-1 YEAR
-40 to 125
I333
INA333AIDGKTG4
ACTIVE
VSSOP
DGK
8
250
Green (RoHS
& no Sb/Br)
NIPDAUAG
Level-2-260C-1 YEAR
-40 to 125
I333
INA333AIDRGR
ACTIVE
SON
DRG
8
3000
Green (RoHS
& no Sb/Br)
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
I333A
INA333AIDRGT
ACTIVE
SON
DRG
8
250
Green (RoHS
& no Sb/Br)
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
I333A
(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
工商网监
湘ICP备2023018690号
