®
INA155
INA
155
INA
155
For most current data sheet and other product
information, visit www.burr-brown.com
Single-Supply, Rail-to-Rail Output, CMOS
INSTRUMENTATION AMPLIFIER
FEATURES
APPLICATIONS
● RAIL-TO-RAIL OUTPUT SWING: Within 10mV
● INDUSTRIAL SENSOR AMPLIFIERS
Bridge, RTD, Thermocouple, Flow, Position
● LOW OFFSET VOLTAGE: ±200µV
● LOW OFFSET DRIFT: ±5µV/°C
● MEDICAL EQUIPMENT
ECG, EEG, EMG Amplifiers
● INTERNAL FIXED GAIN = 10V/V OR 50V/V
● SPECIFIED TEMPERATURE RANGE:
–55°C to +125°C
● DRIVING A/D CONVERTERS
● PCMCIA CARDS
● LOW INPUT BIAS CURRENT: 0.2pA
● WIDE BANDWIDTH: 550kHz in G = 10
● AUDIO PROCESSING
● COMMUNICATIONS
● HIGH SLEW RATE: 6.5V/µs
● LOW COST
● TEST EQUIPMENT
● LOW COST AUTOMOTIVE INSTRUMENTATION
● SO-8 AND TINY MSOP-8 PACKAGES
DESCRIPTION
The INA155 is a low-cost CMOS instrumentation
amplifier with rail-to-rail output swing optimized for
low voltage, single-supply operation.
Gain can be set to 10V/V or 50V/V by pin strapping.
Gains between these two values can be obtained with
the addition of a single resistor. The INA155 is fully
specified over the supply range of +2.7 to +5.5V.
Wide bandwidth (550kHz in G = 10) and high slew
rate (6.5V/µs) make the INA155 suitable for driving
sampling A/D converters as well as general purpose
and audio applications. Fast settling time allows use
with higher speed sensors and transducers and rapid
scanning data acquisition systems.
RG
The INA155 is available in MSOP-8 and SO-8 surface-mount packages. Both are specified for operation
over the temperature range –55°C to 125°C.
G = 10 pins open
G = 50 pins connected
1
V+
RG
8
7
INA155
5kΩ
Ref
5
200kΩ
5kΩ
22.2kΩ
22.2kΩ
200kΩ
+
–
VO = (VIN – VIN) • G + VREF
–
VIN
2
V+
3
A1
6
A2
VO
IN
4
V–
International Airport Industrial Park • Mailing Address: PO Box 11400, Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 • Tel: (520) 746-1111
Twx: 910-952-1111 • Internet: http://www.burr-brown.com/ • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132
©1999 Burr-Brown Corporation
SBOS114
PDS-1529B
Printed in U.S.A. February, 2000
SPECIFICATIONS: VS = +2.7V to +5.5V
Boldface limits apply over the specified temperature range, TA = –40°C to +85°C
At TA = +25°C, RL = 10kΩ connected to VS/2. RG pins open (G = 10), and Ref = VS /2, unless otherwise noted.
INA155E, U
PARAMETER
CONDITION
INPUT
Offset Voltage, RTI
Over Temperature
Drift
vs Power Supply
Over Temperature
vs Time
VOS
dVOS/dT
PSRR
MIN
INA155EA, UA
TYP
VS = +5.0V, VCM = VS/2
±0.2
VS = +2.7V to +6V, VCM = 0.2 • VS
±5
±50
MAX
MIN
±1
TYP
MAX
UNITS
✽
✽
✽
mV
mV
µV/°C
µV/V
µV/V
µV/mo
±1.5
✽
✽
±200
±250
±0.4
✽
✽
✽
INPUT VOLTAGE RANGE
Safe Input Voltage
Common-Mode Range(1)
Common-Mode Rejection Ratio
Over Temperature
VCM
CMRR
VS = 5.5V
VS = 2.7V
VS = 5.5V, 0.6V < VCM < 3.7V, G = 10
VS = 5.5V, 0.6V < V CM < 3.7V, G = 50
Over Temperature
(V–) – 0.5
0.3
0.2
92
85
86
(V+) + 0.5
5.2(2)
2.5(2)
100
90
85
INPUT IMPEDANCE
Differential
Common-Mode
✽
✽
✽
80
79
77
NOISE, RTI
Voltage Noise: f = 0.1Hz to 10Hz
Voltage Noise Density: f = 10Hz
f = 100Hz
f = 1kHz
Current Noise: f = 1kHz
✽
✽
Ω || pF
Ω || pF
✽
✽
VS = 5.5V, VO = 0.05V to 5.45V, G = 50
vs Temperature
Nonlinearity
Over Temperature
OUTPUT
Voltage Output Swing from Rail
Over Temperature
Short-Circuit Current
Capacitance Load (stable operation)
FREQUENCY RESPONSE
Bandwidth, –3dB
BW
Slew Rate
Settling Time: 0.1%
SR
tS
0.01%
10
50
G = 10 + 400kΩ/(10kΩ + RG)
±0.02
±0.1
±2
±10
±0.05
±0.25
±15
±30
✽
✽
✽
✽
✽
✽
VS = 5.5V, G = 10 or 50
±0.005
RL = 10kΩ, GERR < 0.1%
5
Short Circuit to Ground
±50
See Typical Curve
✽
✽
G = 10
G = 50
VS = 5.5V, CL = 100pF
VS = 5.5V, VO = 2V Step, CL = 100pF, G = 10
VS = 5.5V, VO = 2V Step, CL = 100pF, G = 50
VS = 5.5V, VO = 2V Step, CL = 100pF, G = 10
VS = 5.5V, VO = 2V Step, CL = 100pF, G = 50
50% Input Overload
550
110
6.5
5
11
8
15
0.2
See Typical Curve
✽
✽
✽
✽
✽
✽
✽
✽
✽
THD+N
POWER SUPPLY
Specified Voltage Range
Operating Voltage Range
Quiescent Current
Over Temperature
✽
+2.7
VIN = 0, IO = 0
VIN = 0, IO = 0
–40
–65
–65
✽
✽
✽
% of FSR
% of FSR
10
10
✽
✽
✽
mV
mV
mA
✽
kHz
kHz
V/µs
µs
µs
µs
µs
µs
✽
✽
✽
2.1
2.6
+85
+150
+150
✽
✽
✽
θJA
150
150
✽
✽
✽
✽
V/V
V/V
%
ppm/°C
%
ppm/°C
±0.015
±0.015
+5.5
+2.5 to +6
1.7
pA
pA
µV/Vp-p
nV/√Hz
nV/√Hz
nV/√Hz
fA/√Hz
✽
✽
✽
✽
✽
4.5
260
99
40
2
VS = 5.5V, VO = 0.01V to 5.49V, G = 10
TEMPERATURE RANGE
Specified Range
Operating Range
Storage Range
Thermal Resistance
MSOP-8 Surface Mount
SO-8 Surface Mount
±10
±10
V
V
V
dB
dB
dB
dB
RS = 0Ω, G = 10 or 50
GAIN
Gain Equation
Gain Error(3)
vs Temperature
Overload Recovery
Total Harmonic Distortion + Noise
✽
✽
✽
±1
±1
IB
IOS
✽
76
1013 || 3
1013 || 3
INPUT BIAS CURRENT
Input Bias Current
Offset Current
✽
✽
✽
✽
✽
✽
✽
V
V
mA
mA
✽
✽
✽
°C
°C
°C
°C/W
°C/W
✽ Same as INA155E, U.
NOTES: (1) For further information, refer to typical performance curves on common-mode input range. (2) Operation above (V+) – 1.8V (max) results in reduced common-mode
rejection. See discussion and Figure 6 in the text of this data sheet. (3) Does not include error and TCR of additional optional gain-setting resistor in series with RG, if used.
®
INA155
2
SPECIFICATIONS: VS = +2.7V to +5.5V
Boldface limits apply over the specified temperature range, TA = –55°C to +125°C
At TA = +25°C, RL = 10kΩ connected to VS/2. RG pins open (G = 10), and Ref = VS /2, unless otherwise noted.
INA155E, U
PARAMETER
CONDITION
INPUT
Offset Voltage, RTI
Over Temperature
Drift
vs Power Supply
Over Temperature
vs Time
VOS
dVOS/dT
PSRR
MIN
INA155EA, UA
TYP
MAX
VS = +5.0V, VCM = VS/2
±0.2
VS = +2.7V to +6V, VCM = 0.2 • VS
±5
±50
±1
±2
MIN
MAX
UNITS
✽
✽
✽
mV
mV
µV/°C
µV/V
µV/V
µV/mo
✽
✽
±200
±250
±0.4
TYP
✽
✽
✽
INPUT VOLTAGE RANGE
Safe Input Voltage
Common-Mode Range(1)
Common-Mode Rejection Ratio
Over Temperature
VCM
CMRR
VS = 5.5V
VS = 2.7V
VS = 5.5V, 0.6V < VCM < 3.7V, G = 10
VS = 5.5V, 0.6V < V CM < 3.7V, G = 50
Over Temperature
(V–) – 0.5
0.3
0.2
92
82
86
✽
✽
✽
✽
✽
76
±10
±10
✽
✽
Ω || pF
Ω || pF
✽
✽
RS = 0Ω, G = 10 or 50
10
50
G = 10 + 400kΩ/(10kΩ + RG)
±0.02
±0.1
±2
±10
±0.05
±0.25
±15
±30
VS = 5.5V, VO = 0.01V to 5.49V, G = 10
VS = 5.5V, VO = 0.05V to 5.45V, G = 50
vs Temperature
Nonlinearity
Over Temperature
OUTPUT
Voltage Output Swing from Rail
Over Temperature
Short-Circuit Current
Capacitance Load (stable operation)
FREQUENCY RESPONSE
Bandwidth, –3dB
BW
Slew Rate
Settling Time: 0.1%
SR
tS
0.01%
✽
✽
✽
✽
✽
✽
VS = 5.5V, G = 10 or 50
±0.005
RL = 10kΩ, GERR < 0.1%
5
Short Circuit to Ground
±50
See Typical Curve
✽
✽
G = 10
G = 50
VS = 5.5V, CL = 100pF
VS = 5.5V, VO = 2V Step, CL = 100pF, G = 10
VS = 5.5V, VO = 2V Step, CL = 100pF, G = 50
VS = 5.5V, VO = 2V Step, CL = 100pF, G = 10
VS = 5.5V, VO = 2V Step, CL = 100pF, G = 50
50% Input Overload
550
110
6.5
5
11
8
15
0.2
See Typical Curve
✽
✽
✽
✽
✽
✽
✽
✽
✽
THD+N
POWER SUPPLY
Specified Voltage Range
Operating Voltage Range
Quiescent Current
Over Temperature
✽
+2.7
VIN = 0, IO = 0
VIN = 0, IO = 0
–55
–65
–65
✽
✽
✽
% of FSR
% of FSR
10
10
✽
✽
✽
mV
mV
mA
✽
kHz
kHz
V/µs
µs
µs
µs
µs
µs
✽
✽
✽
2.1
2.8
+125
+150
+150
✽
✽
✽
θJA
150
150
✽
✽
✽
✽
V/V
V/V
%
ppm/°C
%
ppm/°C
±0.015
±0.015
+5.5
+2.5 to +6
1.7
pA
pA
µV/Vp-p
nV/√Hz
nV/√Hz
nV/√Hz
fA/√Hz
✽
✽
✽
✽
✽
4.5
260
99
40
2
V
V
V
dB
dB
dB
dB
✽
✽
±1
±1
IB
IOS
GAIN
Gain Equation
Gain Error(3)
vs Temperature
TEMPERATURE RANGE
Specified Range
Operating Range
Storage Range
Thermal Resistance
MSOP-8 Surface Mount
SO-8 Surface Mount
90
✽
✽
✽
80
78
77
1013 || 3
1013 || 3
NOISE, RTI
Voltage Noise: f = 0.1Hz to 10Hz
Voltage Noise Density: f = 10Hz
f = 100Hz
f = 1kHz
Current Noise: f = 1kHz
Overload Recovery
Total Harmonic Distortion + Noise
100
84
INPUT IMPEDANCE
Differential
Common-Mode
INPUT BIAS CURRENT
Input Bias Current
Offset Current
(V+) + 0.5
5.2(2)
2.5(2)
✽
✽
✽
✽
V
V
mA
mA
✽
✽
✽
°C
°C
°C
°C/W
°C/W
✽ Same as INA155E, U.
NOTES: (1) For further information, refer to typical performance curves on common-mode input range. (2) Operation above (V+) – 1.8V (max) results in reduced common-mode
rejection. See discussion and Figure 6 in the text of this data sheet. (3) Does not include error and TCR of additional optional gain-setting resistor in series with RG, if used.
®
3
INA155
ELECTROSTATIC
DISCHARGE SENSITIVITY
PIN CONFIGURATION
Top View
SO-8 (U), MSOP-8 (E)
RG
1
V–
8
RG
IN
2
V+
7
V+
IN
3
6
VOUT
V–
4
5
Ref
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.
INA155
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.
ABSOLUTE MAXIMUM RATINGS(1)
Supply Voltage, V+ to V– ................................................................... 7.5V
Signal Input Terminals, Voltage(2) .................. (V–) – 0.5V to (V+) + 0.5V
Current(2) .................................................... 10mA
Output Short-Circuit(3) .............................................................. Continuous
Operating Temperature .................................................. –65°C to +150°C
Storage Temperature ..................................................... –65°C to +150°C
Junction Temperature .................................................................... +150°C
Lead Temperature (soldering, 10s) ............................................... +300°C
NOTE: (1) 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.
(2) Input terminals are diode-clamped to the power supply rails. Input signals
that can swing more that 0.5V beyond the supply rails should be current limited
to 10mA or less. (3) Short circuit to ground.
PACKAGE/ORDERING INFORMATION
PRODUCT
PACKAGE
PACKAGE
DRAWING
NUMBER
INA155U
"
INA155UA
"
INA155E
"
INA155EA
"
SO-8
"
SO-8
"
MSOP-8
"
MSOP-8
"
182
"
182
"
337
"
337
"
SPECIFIED
TEMPERATURE
RANGE
PACKAGE
MARKING
ORDERING
NUMBER(1)
TRANSPORT
MEDIA
–55°C to
"
–55°C to
"
–55°C to
"
–55°C to
"
INA155U
"
INA155UA
"
A55
"
A55
"
INA155U
INA155U/2K5
INA155UA
INA155UA/2K5
INA155E/250
INA155E/2K5
INA155EA/250
INA155EA/2K5
Rails
Tape and Reel
Rails
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
+125°C
+125°C
+125°C
+125°C
NOTES: (1) Models with a slash (/) are available only in Tape and Reel in the quantities indicated (e.g., /2K5 indicates 2500 devices per reel). Ordering 2500 pieces
of “INA155UA/2K5” will get a single 2500-piece Tape and Reel.
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.
®
INA155
4
TYPICAL PERFORMANCE CURVES
At TA = +25°C, VS = 5.5V, RL = 10kΩ connected to VS/2. RG pins open (G = 10), and Ref = VS /2, unless otherwise noted.
COMMON-MODE REJECTION RATIO vs FREQUENCY
GAIN vs FREQUENCY
120
40
G = 10
35
100
30
G = 50
80
CMRR (dB)
Gain (dB)
25
20
G =10
15
G = 50
60
40
10
20
5
0
0
1
10
100
1k
10k
100k
1M
0.1
10M
1
10
100
POWER SUPPLY REJECTION RATIO vs FREQUENCY
10k
100k
MAXIMUM OUTPUT VOLTAGE vs FREQUENCY
100
6
Maximum Output Voltage (Vp-p)
90
80
70
60
50
40
30
20
10
5
4
3
2
1
VS = 5.5V
0
0
1
10
100
1k
10k
100k
1M
1
10
100
1k
10k
100k
1M
Frequency (Hz)
Frequency (Hz)
SHORT-CIRCUIT CURRENT AND QUIESCENT CURRENT
vs POWER SUPPLY
QUIESCENT CURRENT AND SHORT-CIRCUIT CURRENT
vs TEMPERATURE
55
1.8
2.5
1.75
2.0
100
–ISC
50
–ISC
80
+ISC
+ISC
1.7
45
IQ
35
1.6
30
1.55
2.5
3
3.5
4.0
4.5
5
5.5
60
IQ
1.0
40
0.5
20
0
1.5
25
IQ (mA)
1.65
40
IQ (mA)
ISC (mA)
1.5
0
75
6
Short-Circuit Current (mA)
PSRR (dB)
1k
Frequency (Hz)
Frequency (Hz)
–50
–25
0
25
50
75
100
125
150
Temperature (°C)
Supply Voltage (V)
®
5
INA155
TYPICAL PERFORMANCE CURVES
(Cont.)
At TA = +25°C, VS = 5.5V, RL = 10kΩ connected to VS/2. RG pins open (G = 10), and Ref = VS /2, unless otherwise noted.
TOTAL HARMONIC DISTORTION + NOISE
vs FREQUENCY
INPUT VOLTAGE AND CURRENT NOISE DENSITY
vs FREQUENCY
10k
1
100
10
in
100
1
RL = 2kΩ
0.1
THD+N (%)
1k
Current Noise (fA/√Hz)
Voltage Noise (nV/√Hz)
RL = 600Ω
en
G = 50
RL = 600Ω
RL = 10kΩ
0.01
G = 10
RL = 2kΩ
10
0.1
10
1
100
1k
10k
RL =10kΩ
0.001
0.1
100k
10
100
1k
10k
Frequency (Hz)
Frequency (Hz)
0.1Hz TO 10Hz VOLTAGE NOISE
INPUT BIAS CURRENT vs TEMPERATURE
10k
1µV/div
Input Bias Current (pA)
1k
100
10
1
Input-Referred
0.1
–75
500ms/div
–50
–25
0
25
50
75
100
125
150
125
150
Temperature (°C)
SLEW RATE vs POWER SUPPLY
SLEW RATE vs TEMPERATURE
10
7
9
8
6
Slew Rate (V/µs)
Slew Rate (Vµs)
6.5
5.5
5
7
6
5
4
3
2
4.5
1
0
4
2.5
3
3.5
4
4.5
5
5.5
75
6
®
INA155
–50
–25
0
25
50
Temperature (°C)
Supply Voltage (V)
6
75
100
TYPICAL PERFORMANCE CURVES
(Cont.)
At TA = +25°C, VS = 5.5V, RL = 10kΩ connected to VS/2. RG pins open (G = 10), and Ref = VS /2, unless otherwise noted.
OFFSET VOLTAGE DRIFT
PRODUCTION DISTRIBUTION
OFFSET VOLTAGE
PRODUCTION DISTRIBUTION
18
14
16
Percent of Amplifiers (%)
Percent of Amplifiers (%)
12
10
8
6
4
2
14
12
10
8
6
4
2
0
–1
–0.9
–0.8
–0.7
–0.6
–0.5
–0.4
–0.3
–0.2
–0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
–20
–18
–16
–14
–12
–10
–8
–6
–4
–2
0
2
4
6
8
10
12
14
16
18
20
0
Offset Voltage Drift (µV/°C)
Offset Voltage (mV)
SETTLING TIME vs LOAD CAPACITANCE
OVERSHOOT vs LOAD CAPACITANCE
20
60
18
12
Overshoot (%)
14
0.1%, G = 50
10
0.01%, G = 10
8
6
0.1%, G = 10
40
G = 10
30
20
G = 50
4
10
2
0
0
10
100
1k
10k
10
Load Capacitance (pF)
100
1k
10k
Load Capacitance (pF)
SMALL-SIGNAL STEP RESPONSE
G = 10, CL = 100pF, RL = 10kΩ
SMALL-SIGNAL STEP RESPONSE
G = 50, CL = 100pF, RL = 10kΩ
100mV/div
100mV/div
Settling Time (µs)
50
0.01%, G = 50
16
5µs/div
5µs/div
®
7
INA155
TYPICAL PERFORMANCE CURVES
(Cont.)
At TA = +25°C, VS = 5.5V, RL = 10kΩ connected to VS/2. RG pins open (G = 10), and Ref = VS /2, unless otherwise noted.
LARGE-SIGNAL STEP RESPONSE
G = 10, G = 50, CL = 100pF, RL = 10kΩ
2mV/div
1V/div
1V/div
COMMON-MODE REJECTION AT 60Hz
1µs/div
5ms/div
INPUT COMMON-MODE RANGE
vs REFERENCE VOLTAGE, G = 10
INPUT COMMON-MODE RANGE
vs OUTPUT VOLTAGE, G = 50
6
6
G = 50
5
4
4
VCM (V)
5
3
2
3
Ref = 0V
Ref = 2.75V
Ref = 5.5V
2
0.9V– + 0.1VREF < VCM < 0.9V+ + 0.1Ref
1
0.9V– + 0.04VOUT + 0.06Ref < VCM < 0.9V+ + 0.04VOUT + 0.06Ref
1
0
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
0
0.5
1
1.5
VREF (V)
OUTPUT VOLTAGE SWING vs OUTPUT CURRENT
5
4
+125°C
–55°C
+25°C
3
2
+125°C
–55°C
+25°C
1
0
0
10
20
30
40
50
60
Output Current (mA)
®
INA155
2
2.5
3
VOUT (V)
Output Voltage (V)
VCM (V)
G = 10
8
70
80
90
100
3.5
4
4.5
5
5.5
APPLICATIONS INFORMATION
OPERATING VOLTAGE
Figure 1 shows the basic connections required for operation
of the INA155. Applications with noisy or high impedance
power supplies may require decoupling capacitors close to
the device pins as shown.
The INA155 is fully specified and guaranteed over the supply
range +2.7V to +5.5V, with key parameters guaranteed over
the temperature range of –55°C to +125°C. Parameters that
vary significantly with operating voltages, load conditions or
temperature are shown in the Typical Performance Curves.
The output is referred to the output reference terminal, Ref,
which is normally set to VS/2. This must be a low-impedance connection to ensure good common-mode rejection. A
resistance of 200Ω in series with the Ref pin will cause a
typical device to degrade to approximately 80dB CMRR.
The INA155 can be operated from either single or dual
power supplies. By adjusting the voltage applied to the
reference terminal, the input common-mode voltage range
and the output range can be adjusted within the bounds
shown in the Typical Performance Curves. Figure 2 shows
a bridge amplifier circuit operated from a single +5V power
supply. The bridge provides a relatively small differential
voltage on top of an input common-mode voltage near 2.5V.
In addition, for the G = 50 configuration, the connection
between pins 1 and 8 must be low-impedance. A connection
impedance of 20Ω can cause a 0.2% shift in gain error.
External Resistor RG:
10 < G < 50
V+
Gain Pins Connected:
G = 50
0.1µF
Gain Pins Open:
G = 10
1
7
G = 10 +
8
5kΩ
Ref
–
VIN
V+
5
200kΩ
DESIRED GAIN
(V/V)
RG
(Ω)
10
20
30
40
50
Open
30k
10k
3.3k
Short
5kΩ
22.2kΩ
400kΩ
10kΩ + RG
22.2kΩ
200kΩ
A1
2
6
A2
3
+
–
VOUT = (VIN
– VIN
) • G + VREF
IN
Also drawn in simplified form:
V+
INA155
4
+
VIN
3
1
0.1µF
Single Supply
–
VIN
Dual Supply
7
4
V–
V–
VOUT
5
8
2
6
INA155
Ref
FIGURE 1. Basic Connections.
+5V
(2)
Bridge
Sensor
+
VIN
3
1
V–
IN
7
INA155
VOUT = 0.01V to 4.99V
4
8
2
6
5
NOTES: (1) VREF should be adjusted for the desired output level,
keeping in mind that the value of VREF affects the common-mode
input range. See Typical Performance Curve. (2) For best
performance, the common-mode input voltage should be kept away
from the transition range of (V+) – 1.8V to (V+) –0.8V.
VREF(1)
FIGURE 2. Single-Supply Bridge Amplifier.
®
9
INA155
SETTING THE GAIN
an optional circuit for trimming the output offset voltage.
The voltage applied to the Ref terminal is added to the
output signal. An op amp buffer is used to provide low
impedance at the Ref terminal to preserve good commonmode rejection.
Gain of 10 is achieved simply by leaving the two gain pins
(1 and 8) open. Gain of 50 is achieved by connecting the
gain pins together directly. In the G = 10 configuration, the
gain error is less than 0.1%. In the G = 50 configuration, the
gain error is less than 0.25%.
INPUT BIAS CURRENT RETURN
Gain can be set to any value between 10 and 50 by connecting a resistor RG between the gain pins according to the
following equation:
10 + 400kΩ/(10kΩ + RG)
The input impedance of the INA155 is extremely high—
approximately 1013Ω, making it ideal for use with high-impedance sources. However, a path must be provided for the input
bias current of both inputs. This input bias current is less than
10pA and is virtually independent of the input voltage.
(1)
This is demonstrated in Figure 1 and is shown with the commonly used gains and resistor RG values. However, because the
absolute value of internal resistors is not guaranteed, using the
INA155 in this configuration will increase the gain error and
gain error drift with temperature, as shown in Figure 3.
If the differential source resistance is low, the bias current
return path can be connected to one input (see the thermocouple in Figure 5). With higher source impedance, using
two equal resistors provides a balanced input with advantages of lower input offset voltage due to bias current and
better high-frequency common-mode rejection.
400
2.0
360
Gain Error Drift
1.6
320
1.4
280
1.2
250
200
1.0
0.8
160
Gain Error
0.6
120
0.4
80
0.2
40
Gain Error Drift (ppm/°C)
1.8
Gain Error (%)
Input circuitry must provide a path for this input bias current
for proper operation. Figure 5 shows various provisions for
an input bias current path. Without a bias current path, the
inputs will float to a potential that exceeds the commonmode range and the input amplifier will saturate.
3
10
15
25
20
35
30
40
45
1
Microphone,
Hydrophone, etc.
0
0
6
INA155
8
50
2
Gain (V/V)
5
47kΩ
VREF
VB(1)
FIGURE 3. Typical Gain Error and Gain Error Drift with
External Resistor.
3
OFFSET TRIMMING
1
Thermocouple
The INA155 is laser trimmed for low offset voltage. In most
applications, no external offset adjustment is required. However, if necessary, the offset can be adjusted by applying a
correction voltage to the reference terminal. Figure 4 shows
6
INA155
8
2
5
10kΩ
VREF
Low-resistance
thermocouple
provides bias
current return.
VB(1)
3
1
3
+(2)
VIN
6
INA155
8
1
6
INA155
8
–(2)
VIN
2
5
2
VO
VB(1)
Ref(1)
VREF
Center-tap
provides bias
current return
VEX
OPA336
Bridge
Sensor
Adjustable
Voltage
3
1
6
INA155
8
NOTES: (1) VREF should be adjusted for the desired output
level. The value of VREF affects the common-mode input
range. (2) For best performance, common-mode input voltage
should be less than (V+) – 1.8V or greater than (V+) – 0.8V.
2
NOTE: (1) VB is bias voltage within
common-mode range, dependent
on VREF.
FIGURE 4. Optional Trimming of Output Offset Voltage.
5
VREF
Bridge resistance
provides bias
current return
FIGURE 5. Providing an Input Common-Mode Current Path.
®
INA155
5
10
INPUT COMMON-MODE RANGE
1.00
The input common-mode range of the INA155 for various
operating conditions is shown the in Typical Performance
Curves. The common-mode input range is limited by the
output voltage swing of A1, an internal circuit node. For the G
= 10 configuration, output voltage of A1 can be expressed as:
Input Offset Voltage (mV)
VOUTA1 = – 1/9VREF + (1 + 1/9) VIN–
(2)
Using this equation given that the output of A1 can swing to
within 10mV of either rail, the input common-mode voltage
range can be calculated. When the input common-mode range
is exceeded (A1’s output is saturated), A2 can still be in linear
operation and respond to changes in the non-inverting input
voltage. However, the output voltage will be invalid.
Transistion
Region
P-Channel Operation
0.80
0.60
N-Channel
Operation
0.40
0.20
0.00
–0.20
–0.40
–0.60
VS = –1.8V
–0.80
VS = 5.5V
VS = –0.8V
–0.100
0.0
1.5 2.0
0.5 1.0
2.5
3.0 3.5
4.0
4.5 5.0
5.5
Input Common-Mode Voltage (V)
FIGURE 6. Input Offset Voltage Changes with CommonMode Voltage.
The common-mode range for the G = 50 configuration is
included in the Typical Performance Curve, “Input Common-Mode Range vs Output Voltage.”
V+
NOTE: Output is referred to V+.
INPUT RANGE FOR BEST ACCURACY
The internal amplifiers have rail-to-rail input stages, achieved
by using complementary n- and p-channel input pairs. The
common-mode input voltage determines whether the
p-channel or the n-channel input stage is operating. The
transition between the input stages is gradual and occurs
between (V+) – 1.8V to (V+) – 0.8V. Due to these characteristics operating the INA155 with input voltages within the
transition region of (V+) – 1.8V to (V+) – 0.8V results in a
shift in input offset voltage and reduced common-mode and
power supply rejection performance. Typical patterns of the
offset voltage change throughout the input common-mode
range are illustrated in Figure 6. The INA155 can be
operated below or above the transition region with excellent
results. Figure 7 demonstrates the use of the INA155 in a
single-supply, high-side current monitor. In this application, the INA155 is operated above the transition region.
2
5
7
0.02Ω
1
50mV
6
INA155
4
8
3
IL
2.5A
Load
G = 10
Pins 1 and 8 Open
FIGURE 7. Single-Supply, High-Side Current Monitor.
RLIM
RAIL-TO-RAIL OUTPUT
3
IOVERLOAD
10mA max
A class AB output stage with common-source transistors
is used to achieve rail-to-rail output. For resistive loads
greater than 10kΩ, the output voltage can swing to within
a few millivolts of the supply rail while maintaining low
gain error. For heavier loads and over temperature, see the
typical performance curve “Output Voltage Swing vs Output Current.” The INA155’s low output impedance at high
frequencies makes it suitable for directly driving Capacitive Digital-to-Analog (CDAC) input A/D converters, as
shown in Figure 9.
1
8
6
INA155
VOUT
5
2
RLIM
VREF
FIGURE 8. Input Current Protection for Voltages Exceeding the Supply Voltage.
+5V
INPUT PROTECTION
3
Device inputs are protected by ESD diodes that will conduct
if the input voltages exceed the power supplies by more than
500mV. Momentary voltages greater than 500mV beyond
the power supply can be tolerated if the current on the input
pins is limited to 10mA. This is easily accomplished with
input resistors RLIM as shown in Figure 8. Many input
signals are inherently current-limited to less than 10mA,
therefore, a limiting resistor is not required.
1
7
5
8
2
6
INA155
4
ADS7818
or
ADS7834
12-Bits
fSAMPLE = 500kHz
NOTE: G = 10 configuration
FIGURE 9. INA155 Directly Drives Capacitive-Input, HighSpeed A/D Converter.
®
11
INA155
PACKAGE OPTION ADDENDUM
www.ti.com
14-Oct-2022
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)
Samples
(4/5)
(6)
INA155E/250
ACTIVE
VSSOP
DGK
8
250
RoHS & Green
Call TI
Level-2-260C-1 YEAR
INA155EA/250
ACTIVE
VSSOP
DGK
8
250
RoHS & Green
Call TI
INA155EA/2K5
ACTIVE
VSSOP
DGK
8
2500
RoHS & Green
INA155U
ACTIVE
SOIC
D
8
75
INA155U/2K5
ACTIVE
SOIC
D
8
INA155UA
ACTIVE
SOIC
D
INA155UA/2K5
ACTIVE
SOIC
INA155UG4
ACTIVE
SOIC
-40 to 85
A55
Samples
Level-2-260C-1 YEAR
A55
Samples
Call TI
Level-2-260C-1 YEAR
A55
Samples
RoHS & Green
Call TI
Level-2-260C-1 YEAR
INA
155U
Samples
2500
RoHS & Green
Call TI
Level-2-260C-1 YEAR
INA
155U
Samples
8
75
RoHS & Green
Call TI
Level-2-260C-1 YEAR
INA
155U
A
D
8
2500
RoHS & Green
Call TI
Level-2-260C-1 YEAR
INA
155U
A
D
8
75
RoHS & Green
Call TI
Level-2-260C-1 YEAR
INA
155U
(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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