®
INA155
©1999 Burr-Brown Corporation PDS-1529B Printed in U.S.A. February, 2000
FEATURES
●RAIL-TO-RAIL OUTPUT SWING: Within 10mV
●LOW OFFSET VOLTAGE: ±200µV
●LOW OFFSET DRIFT: ±5µV/°C
●INTERNAL FIXED GAIN = 10V/V OR 50V/V
●SPECIFIED TEMPERATURE RANGE:
–55°C to +125°C
●LOW INPUT BIAS CURRENT: 0.2pA
●WIDE BANDWIDTH: 550kHz in G = 10
●HIGH SLEW RATE: 6.5V/µs
●LOW COST
●SO-8 AND TINY MSOP-8 PACKAGES
Single-Supply, Rail-to-Rail Output, CMOS
INSTRUMENTATION AMPLIFIER
DESCRIPTION
The INA155 is a low-cost CMOS instrumentation
amplifier with rail-to-rail output swing optimized for
low voltage, single-supply operation.
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.
APPLICATIONS
●INDUSTRIAL SENSOR AMPLIFIERS
Bridge, RTD, Thermocouple, Flow, Position
●MEDICAL EQUIPMENT
ECG, EEG, EMG Amplifiers
●DRIVING A/D CONVERTERS
●PCMCIA CARDS
●AUDIO PROCESSING
●COMMUNICATIONS
●TEST EQUIPMENT
●
LOW COST AUTOMOTIVE INSTRUMENTATION
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
INA155
INA155
For most current data sheet and other product
information, visit www.burr-brown.com
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.
The INA155 is available in MSOP-8 and SO-8 sur-
face-mount packages. Both are specified for operation
over the temperature range –55°C to 125°C.
22.2kΩ200kΩ
V
IN
–
V
IN
+
Ref
R
G
INA155
V
O
22.2kΩ
5kΩ5kΩ
200kΩ
R
G
V+
V–
1
5
2
3
87
4
6
A1
A2
G = 10 pins open
G = 50 pins connected
V
O
= (V
IN
– V
IN
) • G + V
REF
+–
SBOS114
2
®
INA155
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 INA155EA, UA
PARAMETER CONDITION MIN TYP MAX MIN TYP MAX UNITS
INPUT
Offset Voltage, RTI VOS VS = +5.0V, VCM = VS/2 ±0.2 ±1✽✽mV
Over Temperature
±
1.5 ✽mV
Drift dVOS/dT
±
5✽µV/°C
vs Power Supply PSRR VS = +2.7V to +6V, VCM = 0.2 • VS±50 ±200 ✽✽µV/V
Over Temperature
±
250 ✽µV/V
vs Time ±0.4 ✽µV/mo
INPUT VOLTAGE RANGE
Safe Input Voltage (V–) – 0.5 (V+) + 0.5 ✽✽V
Common-Mode Range(1) VCM VS = 5.5V 0.3 5.2(2) ✽✽V
VS = 2.7V 0.2 2.5(2) ✽✽V
Common-Mode Rejection Ratio CMRR VS = 5.5V, 0.6V < VCM < 3.7V, G = 10 92 100 80 ✽dB
Over Temperature 85 79 dB
V
S
= 5.5V, 0.6V < V
CM
< 3.7V, G = 50
86 90 77 ✽dB
Over Temperature 85 76 dB
INPUT IMPEDANCE
Differential 1013 || 3 ✽Ω || pF
Common-Mode 1013 || 3 ✽Ω || pF
INPUT BIAS CURRENT
Input Bias Current IB±1±10 ✽✽pA
Offset Current IOS ±1±10 ✽✽pA
NOISE, RTI RS = 0Ω, G = 10 or 50
Voltage Noise: f = 0.1Hz to 10Hz 4.5 ✽µV/Vp-p
Voltage Noise Density: f = 10Hz 260 ✽nV/√Hz
f = 100Hz 99 ✽nV/√Hz
f = 1kHz 40 ✽nV/√Hz
Current Noise: f = 1kHz 2✽fA/√Hz
GAIN 10 50 ✽✽V/V
Gain Equation G = 10 + 400kΩ/(10kΩ + RG)✽V/V
Gain Error(3)
VS = 5.5V, VO = 0.01V to 5.49V, G = 10
±0.02 ±0.1 ✽✽%
vs Temperature
±
2
±
10 ✽✽ppm/°C
VS = 5.5V, VO = 0.05V to 5.45V, G = 50 ±0.05 ±0.25
✽✽%
vs Temperature
±
15
±
30 ✽✽ppm/°C
Nonlinearity
VS = 5.5V, G = 10 or 50 ±0.005 ±
0.015 ✽✽% of FSR
Over Temperature
±
0.015 ✽% of FSR
OUTPUT
Voltage Output Swing from Rail RL = 10kΩ, GERR < 0.1% 5 10 ✽✽mV
Over Temperature 10 ✽mV
Short-Circuit Current Short Circuit to Ground ±50 ✽mA
Capacitance Load (stable operation) See Typical Curve ✽
FREQUENCY RESPONSE
Bandwidth, –3dB BW G = 10 550 ✽kHz
G = 50 110 ✽kHz
Slew Rate SR VS = 5.5V, CL = 100pF 6.5 ✽V/µs
Settling Time: 0.1% tS
VS = 5.5V, VO = 2V Step, CL = 100pF, G = 10
5✽µs
VS = 5.5V, VO = 2V Step, CL = 100pF, G = 50
11 ✽µs
0.01%
VS = 5.5V, VO = 2V Step, CL = 100pF, G = 10
8✽µs
VS = 5.5V, VO = 2V Step, CL = 100pF, G = 50
15 ✽µs
Overload Recovery 50% Input Overload 0.2 ✽µs
Total Harmonic Distortion + Noise THD+N See Typical Curve ✽
POWER SUPPLY
Specified Voltage Range +2.7 +5.5 ✽✽V
Operating Voltage Range
+2.5 to +6
✽V
Quiescent Current VIN = 0, IO = 0 1.7 2.1 ✽✽mA
Over Temperature VIN = 0, IO = 0 2.6 ✽mA
TEMPERATURE RANGE
Specified Range –40 +85 ✽✽°C
Operating Range –65 +150 ✽✽°C
Storage Range –65 +150 ✽✽°C
Thermal Resistance
θ
JA
MSOP-8 Surface Mount 150 ✽°C/W
SO-8 Surface Mount 150 ✽°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
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 INA155EA, UA
PARAMETER CONDITION MIN TYP MAX MIN TYP MAX UNITS
INPUT
Offset Voltage, RTI VOS VS = +5.0V, VCM = VS/2 ±0.2 ±1✽✽mV
Over Temperature
±
2✽mV
Drift dVOS/dT
±
5✽µV/°C
vs Power Supply PSRR VS = +2.7V to +6V, VCM = 0.2 • VS±50 ±200 ✽✽µV/V
Over Temperature
±
250 ✽µV/V
vs Time ±0.4 ✽µV/mo
INPUT VOLTAGE RANGE
Safe Input Voltage (V–) – 0.5 (V+) + 0.5 ✽✽V
Common-Mode Range(1) VCM VS = 5.5V 0.3 5.2(2) ✽✽V
VS = 2.7V 0.2 2.5(2) ✽✽V
Common-Mode Rejection Ratio CMRR VS = 5.5V, 0.6V < VCM < 3.7V, G = 10 92 100 80 ✽dB
Over Temperature 82 78 dB
V
S
= 5.5V, 0.6V < V
CM
< 3.7V, G = 50
86 90 77 ✽dB
Over Temperature 84 76 dB
INPUT IMPEDANCE
Differential 1013 || 3 ✽Ω || pF
Common-Mode 1013 || 3 ✽Ω || pF
INPUT BIAS CURRENT
Input Bias Current IB±1±10 ✽✽pA
Offset Current IOS ±1±10 ✽✽pA
NOISE, RTI RS = 0Ω, G = 10 or 50
Voltage Noise: f = 0.1Hz to 10Hz 4.5 ✽µV/Vp-p
Voltage Noise Density: f = 10Hz 260 ✽nV/√Hz
f = 100Hz 99 ✽nV/√Hz
f = 1kHz 40 ✽nV/√Hz
Current Noise: f = 1kHz 2✽fA/√Hz
GAIN 10 50 ✽✽V/V
Gain Equation G = 10 + 400kΩ/(10kΩ + RG)✽V/V
Gain Error(3)
VS = 5.5V, VO = 0.01V to 5.49V, G = 10
±0.02 ±0.1 ✽✽%
vs Temperature
±
2
±
10 ✽✽ppm/°C
VS = 5.5V, VO = 0.05V to 5.45V, G = 50 ±0.05 ±0.25
✽✽%
vs Temperature
±
15
±
30 ✽✽ppm/°C
Nonlinearity
VS = 5.5V, G = 10 or 50 ±0.005 ±
0.015 ✽✽% of FSR
Over Temperature
±
0.015 ✽% of FSR
OUTPUT
Voltage Output Swing from Rail RL = 10kΩ, GERR < 0.1% 5 10 ✽✽mV
Over Temperature 10 ✽mV
Short-Circuit Current Short Circuit to Ground ±50 ✽mA
Capacitance Load (stable operation) See Typical Curve ✽
FREQUENCY RESPONSE
Bandwidth, –3dB BW G = 10 550 ✽kHz
G = 50 110 ✽kHz
Slew Rate SR VS = 5.5V, CL = 100pF 6.5 ✽V/µs
Settling Time: 0.1% tS
VS = 5.5V, VO = 2V Step, CL = 100pF, G = 10
5✽µs
VS = 5.5V, VO = 2V Step, CL = 100pF, G = 50
11 ✽µs
0.01%
VS = 5.5V, VO = 2V Step, CL = 100pF, G = 10
8✽µs
VS = 5.5V, VO = 2V Step, CL = 100pF, G = 50
15 ✽µs
Overload Recovery 50% Input Overload 0.2 ✽µs
Total Harmonic Distortion + Noise THD+N See Typical Curve ✽
POWER SUPPLY
Specified Voltage Range +2.7 +5.5 ✽✽V
Operating Voltage Range
+2.5 to +6
✽V
Quiescent Current VIN = 0, IO = 0 1.7 2.1 ✽✽mA
Over Temperature VIN = 0, IO = 0 2.8 ✽mA
TEMPERATURE RANGE
Specified Range –55 +125 ✽✽°C
Operating Range –65 +150 ✽✽°C
Storage Range –65 +150 ✽✽°C
Thermal Resistance
θ
JA
MSOP-8 Surface Mount 150 ✽°C/W
SO-8 Surface Mount 150 ✽°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.
4
®
INA155
PIN CONFIGURATION ELECTROSTATIC
DISCHARGE SENSITIVITY
This integrated circuit can be damaged by ESD. Burr-Brown
recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling
and installation procedures can cause damage.
ESD damage can range from subtle performance degradation
to complete device failure. Precision integrated circuits may
be more susceptible to damage because very small parametric
changes could cause the device not to meet its published
specifications.
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.
Top View SO-8 (U), MSOP-8 (E)
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.
ABSOLUTE MAXIMUM RATINGS(1)
PACKAGE SPECIFIED
DRAWING TEMPERATURE PACKAGE ORDERING TRANSPORT
PRODUCT PACKAGE NUMBER RANGE MARKING NUMBER(1) MEDIA
INA155U SO-8 182 –55°C to +125°C INA155U INA155U Rails
" " " " " INA155U/2K5 Tape and Reel
INA155UA SO-8 182 –55°C to +125°C INA155UA INA155UA Rails
" " " " " INA155UA/2K5 Tape and Reel
INA155E MSOP-8 337 –55°C to +125°C A55 INA155E/250 Tape and Reel
" " " " " INA155E/2K5 Tape and Reel
INA155EA MSOP-8 337 –55°C to +125°C A55 INA155EA/250 Tape and Reel
" " " " " INA155EA/2K5 Tape and Reel
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.
PACKAGE/ORDERING INFORMATION
R
G
V
IN
V
IN
V–
R
G
V+
V
OUT
Ref
1
2
3
4
8
7
6
5
INA155
+
–
5
®
INA155
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.
GAIN vs FREQUENCY
Frequency (Hz)
Gain (dB)
1 10010 1k 10k 1M 10M
40
35
30
25
20
15
10
5
0100k
G = 50
G =10
COMMON-MODE REJECTION RATIO vs FREQUENCY
Frequency (Hz)
CMRR (dB)
0.1 1 10 10k 100k
120
100
80
60
40
20
0100 1k
G = 10
G = 50
POWER SUPPLY REJECTION RATIO vs FREQUENCY
Frequency (Hz)
PSRR (dB)
1 10 10k 100k 1M
100
90
80
70
60
50
40
30
20
10
0100 1k
MAXIMUM OUTPUT VOLTAGE vs FREQUENCY
Frequency (Hz)
Maximum Output Voltage (Vp-p)
1 10 10k 100k 1M
6
5
4
3
2
1
0100 1k
V
S
= 5.5V
SHORT-CIRCUIT CURRENT AND QUIESCENT CURRENT
vs POWER SUPPLY
Supply Voltage (V)
I
SC
(mA)
2.5 34.03.5
55
50
45
40
35
30
25
I
Q
(mA)
1.8
1.75
1.7
1.65
1.6
1.55
1.5
4.5 5.5 6 5
I
Q
+I
SC
–I
SC
QUIESCENT CURRENT AND SHORT-CIRCUIT CURRENT
vs TEMPERATURE
Temperature (°C)
I
Q
(mA)
Short-Circuit Current (mA)
75 –50 0–25
2.5
2.0
1.5
1.0
0.5
0
100
80
60
40
20
0
25 100 125 15050 75
I
Q
+I
SC
–I
SC
6
®
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.
0.1Hz TO 10Hz VOLTAGE NOISE
500ms/div
1µV/div
Input-Referred
TOTAL HARMONIC DISTORTION + NOISE
vs FREQUENCY
1
0.1
0.01
0.001
THD+N (%)
10 100 10k1k
Frequency (Hz)
RL = 600Ω
RL = 600ΩRL = 10kΩ
RL = 2kΩ
G = 50
G = 10
RL =10kΩ
RL = 2kΩ
INPUT BIAS CURRENT vs TEMPERATURE
Temperature (°C)
Input Bias Current (pA)
–75 –50 –25 0
10k
1k
100
10
1
0.1 25 100 125 15050 75
SLEW RATE vs POWER SUPPLY
Supply Voltage (V)
Slew Rate (Vµs)
2.5 343.5
7
6.5
6
5.5
5
4.5
44.5 65 5.5
SLEW RATE vs TEMPERATURE
Temperature (°C)
Slew Rate (V/µs)
75 –50 0–25
10
9
8
7
6
5
4
3
2
1
025 100 125 15050 75
INPUT VOLTAGE AND CURRENT NOISE DENSITY
vs FREQUENCY
Frequency (Hz)
Voltage Noise (nV/√Hz)
0.1 110
10k
1k
100
10
100
10
1
0.1
100 100k1k 10k
Current Noise (fA/√Hz)
e
n
i
n
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.
OFFSET VOLTAGE
PRODUCTION DISTRIBUTION
Percent of Amplifiers (%)
Offset Voltage (mV)
–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
14
12
10
8
6
4
2
0
SETTLING TIME vs LOAD CAPACITANCE
Load Capacitance (pF)
Settling Time (µs)
10 100 10k
20
18
16
14
12
10
8
6
4
2
01k
0.01%, G = 50
0.1%, G = 50
0.01%, G = 10
0.1%, G = 10
OVERSHOOT vs LOAD CAPACITANCE
Load Capacitance (pF)
Overshoot (%)
10 100 10k
60
50
40
30
20
10
01k
G = 10
G = 50
5µs/div
100mV/div
SMALL-SIGNAL STEP RESPONSE
G = 10, CL = 100pF, RL = 10kΩ
5µs/div
100mV/div
SMALL-SIGNAL STEP RESPONSE
G = 50, CL = 100pF, RL = 10kΩ
OFFSET VOLTAGE DRIFT
PRODUCTION DISTRIBUTION
Percent of Amplifiers (%)
Offset Voltage Drift (µV/°C)
–20
–18
–16
–14
–12
–10
–8
–6
–4
–2
0
2
4
6
8
10
12
14
16
18
20
18
16
14
12
10
8
6
4
2
0
8
®
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.
1µs/div
1V/div
LARGE-SIGNAL STEP RESPONSE
G = 10, G = 50, CL = 100pF, RL = 10kΩ
INPUT COMMON-MODE RANGE
vs OUTPUT VOLTAGE, G = 50
V
OUT
(V)
V
CM
(V)
00.5 1 21.5
6
5
4
3
2
1
02.5 5.53 3.5 4 4.5 5
Ref = 0V Ref = 2.75V Ref = 5.5V
G = 50
0.9V– + 0.04V
OUT
+ 0.06Ref < V
CM
< 0.9V
+
+ 0.04V
OUT
+ 0.06Ref
5ms/div
1V/div
COMMON-MODE REJECTION AT 60Hz
2mV/div
INPUT COMMON-MODE RANGE
vs REFERENCE VOLTAGE, G = 10
V
REF
(V)
V
CM
(V)
00.5 1 21.5
6
5
4
3
2
1
02.5 5.53 3.5 4 4.5 5
G = 10
0.9V
–
+ 0.1V
REF
< V
CM
< 0.9V
+
+ 0.1Ref
OUTPUT VOLTAGE SWING vs OUTPUT CURRENT
Output Current (mA)
Output Voltage (V)
5
4
3
2
1
00 102030405060708090100
+125°C +25°C–55°C
+125°C+25°C–55°C
9
®
INA155
APPLICATIONS INFORMATION
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 output is referred to the output reference terminal, Ref,
which is normally set to VS/2. This must be a low-imped-
ance 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.
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.
OPERATING VOLTAGE
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 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.
FIGURE 1. Basic Connections.
FIGURE 2. Single-Supply Bridge Amplifier.
Bridge
Sensor
INA155
V
REF(1)
+5V
3
2
4
5
76V
OUT
= 0.01V to 4.99V
(2)
NOTES: (1) V
REF
should be adjusted for the desired output level,
keeping in mind that the value of V
REF
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.
1
8
V
IN
+
V
IN
–
Ref 22.2kΩ200kΩ
5kΩ
Gain Pins Open:
G = 10
External Resistor RG:
10 < G < 50
Gain Pins Connected:
G = 50
5kΩ
200kΩ22.2kΩ
4
3
2
5
718
V–
0.1µF
Single Supply
Also drawn in simplified form:
Dual Supply
INA155
INA155
6
1
3
8
2
VOUT
6
7
4
5
Ref
0.1µF
V+
V+
V–
DESIRED GAIN RG
(V/V) (Ω)
10 Open
20 30k
30 10k
40 3.3k
50 Short
G = 10 + 400kΩ
10kΩ + RG
VIN
–
VIN
+
A1
A2
VIN
+
VIN
–
VOUT = (VIN – VIN) • G + VREF
+–
10
®
INA155
SETTING THE GAIN
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%.
Gain can be set to any value between 10 and 50 by connect-
ing a resistor RG between the gain pins according to the
following equation:
10 + 400kΩ/(10kΩ + RG) (1)
This is demonstrated in Figure 1 and is shown with the com-
monly 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.
FIGURE 3. Typical Gain Error and Gain Error Drift with
External Resistor.
OFFSET TRIMMING
The INA155 is laser trimmed for low offset voltage. In most
applications, no external offset adjustment is required. How-
ever, if necessary, the offset can be adjusted by applying a
correction voltage to the reference terminal. Figure 4 shows
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 common-
mode rejection.
INPUT BIAS CURRENT RETURN
The input impedance of the INA155 is extremely high—
approximately 1013Ω, making it ideal for use with high-imped-
ance 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.
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 common-
mode range and the input amplifier will saturate.
If the differential source resistance is low, the bias current
return path can be connected to one input (see the thermo-
couple in Figure 5). With higher source impedance, using
two equal resistors provides a balanced input with advan-
tages of lower input offset voltage due to bias current and
better high-frequency common-mode rejection.
FIGURE 4. Optional Trimming of Output Offset Voltage. FIGURE 5. Providing an Input Common-Mode Current Path.
Gain (V/V)
Gain Error (%)
10 15 20 3025
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
Gain Error Drift (ppm/°C)
400
360
320
280
250
200
160
120
80
40
0
35 40 5045
Gain Error Drift
Gain Error
OPA336
INA155
Ref
(1)
3
6
25
V
O
Adjustable
Voltage
V
IN
+
(2)
V
IN
–
(2)
NOTES: (1) V
REF
should be adjusted for the desired output
level. The value of V
REF
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.
1
8
INA155
3
6
6
6
6
25
V
REF
47kΩ
Microphone,
Hydrophone, etc.
INA155
3
2
3
2
5
V
REF
Center-tap
provides bias
current return
Low-resistance
thermocouple
provides bias
current return.
Bridge resistance
provides bias
current return
INA155
3
2
10kΩ5
V
REF
V
B(1)
Thermocouple
INA155
5
V
REF
Bridge
Sensor
1
8
1
8
1
8
1
8
V
B(1)
V
B(1)
V
EX
NOTE: (1) V
B
is bias voltage within
common-mode range, dependent
on V
REF
.
11
®
INA155
INPUT COMMON-MODE RANGE
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:
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.
The common-mode range for the G = 50 configuration is
included in the Typical Performance Curve, “Input Com-
mon-Mode Range vs Output Voltage.”
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 charac-
teristics 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 applica-
tion, the INA155 is operated above the transition region.
RAIL-TO-RAIL OUTPUT
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 Out-
put Current.” The INA155’s low output impedance at high
frequencies makes it suitable for directly driving Capaci-
tive Digital-to-Analog (CDAC) input A/D converters, as
shown in Figure 9.
INPUT PROTECTION
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.
FIGURE 6. Input Offset Voltage Changes with Common-
Mode Voltage.
FIGURE 7. Single-Supply, High-Side Current Monitor.
FIGURE 8. Input Current Protection for Voltages Exceed-
ing the Supply Voltage.
Input Common-Mode Voltage (V)
Input Offset Voltage (mV)
0.0 0.5 1.0 2.5 3.01.5 2.0
1.00
0.80
0.60
0.40
0.20
0.00
–0.20
–0.40
–0.60
–0.80
–0.100 3.5 4.0 5.54.5 5.0
Transistion
Region
P-Channel Operation
V
S
= –1.8V
V
S
= 5.5V
V
S
= –0.8V
N-Channel
Operation
FIGURE 9. INA155 Directly Drives Capacitive-Input, High-
Speed A/D Converter.
INA155
5
V
OUT
V
REF
R
LIM
R
LIM
I
OVERLOAD
10mA max
3
6
2
1
8
INA155
76
4
5
I
L
2.5A
G = 10
Pins 1 and 8 Open
V+ NOTE: Output is referred to V+.
2
3
1
8
0.02Ω
Load
50mV
+5V
INA155 ADS7818
or
ADS7834
12-Bits
f
SAMPLE
= 500kHz
6
7
5
4
3
2
NOTE: G = 10 configuration
1
8
PACKAGE OPTION ADDENDUM
www.ti.com 16-Aug-2012
Addendum-Page 1
PACKAGING INFORMATION
Orderable Device Status (1) Package Type Package
Drawing Pins Package Qty Eco Plan (2) Lead/
Ball Finish MSL Peak Temp (3) Samples
(Requires Login)
INA155E/250 ACTIVE VSSOP DGK 8 250 Green (RoHS
& no Sb/Br) CU NIPDAUAGLevel-2-260C-1 YEAR
INA155E/250G4 ACTIVE VSSOP DGK 8 250 Green (RoHS
& no Sb/Br) CU NIPDAUAGLevel-2-260C-1 YEAR
INA155E/2K5 ACTIVE VSSOP DGK 8 2500 Green (RoHS
& no Sb/Br) CU NIPDAUAGLevel-2-260C-1 YEAR
INA155E/2K5G4 ACTIVE VSSOP DGK 8 2500 Green (RoHS
& no Sb/Br) CU NIPDAUAGLevel-2-260C-1 YEAR
INA155EA/250 ACTIVE VSSOP DGK 8 250 Green (RoHS
& no Sb/Br) CU NIPDAUAGLevel-2-260C-1 YEAR
INA155EA/250G4 ACTIVE VSSOP DGK 8 250 Green (RoHS
& no Sb/Br) CU NIPDAUAGLevel-2-260C-1 YEAR
INA155EA/2K5 ACTIVE VSSOP DGK 8 2500 Green (RoHS
& no Sb/Br) CU NIPDAUAGLevel-2-260C-1 YEAR
INA155EA/2K5G4 ACTIVE VSSOP DGK 8 2500 Green (RoHS
& no Sb/Br) CU NIPDAUAGLevel-2-260C-1 YEAR
INA155U ACTIVE SOIC D 8 75 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
INA155U/2K5 ACTIVE SOIC D 8 2500 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
INA155U/2K5G4 ACTIVE SOIC D 8 2500 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
INA155UA ACTIVE SOIC D 8 75 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
INA155UA/2K5 ACTIVE SOIC D 8 2500 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
INA155UA/2K5G4 ACTIVE SOIC D 8 2500 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
INA155UAG4 ACTIVE SOIC D 8 75 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
INA155UG4 ACTIVE SOIC D 8 75 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
(1) The marketing status values are defined as follows:
PACKAGE OPTION ADDENDUM
www.ti.com 16-Aug-2012
Addendum-Page 2
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) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
(3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device Package
Type Package
Drawing Pins SPQ Reel
Diameter
(mm)
Reel
Width
W1 (mm)
A0
(mm) B0
(mm) K0
(mm) P1
(mm) W
(mm) Pin1
Quadrant
INA155E/250 VSSOP DGK 8 250 180.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1
INA155E/2K5 VSSOP DGK 8 2500 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1
INA155EA/250 VSSOP DGK 8 250 180.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1
INA155EA/2K5 VSSOP DGK 8 2500 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1
INA155U/2K5 SOIC D 8 2500 330.0 12.4 6.4 5.2 2.1 8.0 12.0 Q1
INA155UA/2K5 SOIC D 8 2500 330.0 12.4 6.4 5.2 2.1 8.0 12.0 Q1
PACKAGE MATERIALS INFORMATION
www.ti.com 16-Aug-2012
Pack Materials-Page 1
*All dimensions are nominal
Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)
INA155E/250 VSSOP DGK 8 250 210.0 185.0 35.0
INA155E/2K5 VSSOP DGK 8 2500 367.0 367.0 35.0
INA155EA/250 VSSOP DGK 8 250 210.0 185.0 35.0
INA155EA/2K5 VSSOP DGK 8 2500 367.0 367.0 35.0
INA155U/2K5 SOIC D 8 2500 367.0 367.0 35.0
INA155UA/2K5 SOIC D 8 2500 367.0 367.0 35.0
PACKAGE MATERIALS INFORMATION
www.ti.com 16-Aug-2012
Pack Materials-Page 2
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