INA125 [TI]
具有精密电压参考的仪表放大器;型号: | INA125 |
厂家: | TEXAS INSTRUMENTS |
描述: | 具有精密电压参考的仪表放大器 放大器 仪表 仪表放大器 |
文件: | 总19页 (文件大小:369K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
INA125
®
INA125
INA125
INSTRUMENTATION AMPLIFIER
With Precision Voltage Reference
FEATURES
APPLICATIONS
● LOW QUIESCENT CURRENT: 460µA
● PRESSURE AND TEMPERATURE BRIDGE
AMPLIFIERS
● PRECISION VOLTAGE REFERENCE:
1.24V, 2.5V, 5V or 10V
● INDUSTRIAL PROCESS CONTROL
● FACTORY AUTOMATION
● SLEEP MODE
● LOW OFFSET VOLTAGE: 250µV max
● LOW OFFSET DRIFT: 2µV/°C max
● LOW INPUT BIAS CURRENT: 20nA max
● HIGH CMR: 100dB min
● MULTI-CHANNEL DATA ACQUISITION
● BATTERY OPERATED SYSTEMS
● GENERAL PURPOSE INSTRUMENTATION
SLEEP
2
V+
● LOW NOISE: 38nV/√Hz at f = 1kHz
● INPUT PROTECTION TO ±40V
1
INA125
V
REFCOM
12
13
14
● WIDE SUPPLY RANGE
Single Supply: 2.7V to 36V
Dual Supply: ±1.35V to ±18V
R
V
REFBG
● 16-PIN DIP AND SO-16 SOIC PACKAGES
R
VREF2.5
2R
DESCRIPTION
15
VREF
5
The INA125 is a low power, high accuracy instrumen-
tation amplifier with a precision voltage reference. It
provides complete bridge excitation and precision dif-
ferential-input amplification on a single integrated
circuit.
4R
VREF10 16
4
Ref
Amp
Bandgap
VREF
VREFOut
10V
A single external resistor sets any gain from 4 to
10,000. The INA125 is laser-trimmed for low offset
voltage (250µV), low offset drift (2µV/°C), and high
common-mode rejection (100dB at G = 100). It oper-
ates on single (+2.7V to +36V) or dual (±1.35V to
±18V) supplies.
+
VIN
10
6
9
A1
VO
30kΩ
11
Sense
10kΩ
RG
The voltage reference is externally adjustable with pin-
selectable voltages of 2.5V, 5V, or 10V, allowing use
with a variety of transducers. The reference voltage is
accurate to ±0.5% (max) with ±35ppm/°C drift (max).
Sleep mode allows shutdown and duty cycle operation
to save power.
10kΩ
+
–
VO = (VIN – VIN) G
8
7
G = 4 + 60kΩ
RG
A2
–
VIN
30kΩ
IAREF
5
The INA125 is available in 16-pin plastic DIP and
SO-16 surface-mount packages and is specified for
the –40°C to +85°C industrial temperature range.
3
V–
International Airport Industrial Park
•
Mailing Address: PO Box 11400, Tucson, AZ 85734
FAXLine: (800) 548-6133 (US/Canada Only)
•
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
©1997 Burr-Brown Corporation
PDS-1361B
Printed in U.S.A., February, 1998
SBOS060
SPECIFICATIONS: VS = ±15V
At TA = +25°C, VS = ±15V, IA common = 0V, VREF common = 0V, and RL = 10kΩ, unless otherwise noted.
INA125P, U
INA125PA, UA
TYP
PARAMETER
CONDITIONS
MIN
TYP
MAX
MIN
MAX
UNITS
INPUT
Offset Voltage, RTI
Initial
vs Temperature
vs Power Supply
Long-Term Stability
Impedance, Differential
±50
±0.25
±3
±0.2
1011 || 2
1011 || 9
±250
±2
±20
✻
✻
✻
✻
✻
✻
±500
±5
±50
µV
µV/°C
µV/V
µV/mo
Ω || pF
Ω || pF
V
VS = ±1.35V to ±18V, G = 4
Common-Mode
Safe Input Voltage
±40
✻
Input Voltage Range
Common-Mode Rejection
See Text
✻
VCM = –10.7V to +10.2V
G = 4
78
86
100
100
84
94
114
114
72
80
90
90
✻
✻
✻
✻
dB
dB
dB
dB
G = 10
G = 100
G = 500
BIAS CURRENT
vs Temperature
Offset Current
VCM = 0V
10
25
✻
✻
✻
✻
50
nA
pA/°C
nA
±60
±0.5
±0.5
±2.5
±5
vs Temperature
pA/°C
NOISE, RTI
RS = 0Ω
Voltage Noise, f = 10Hz
f = 100Hz
f = 1kHz
f = 0.1Hz to 10Hz
Current Noise, f = 10Hz
f = 1kHz
40
38
38
0.8
170
56
5
✻
✻
✻
✻
✻
✻
✻
nV/√Hz
nV/√Hz
nV/√Hz
µVp-p
fA/√Hz
fA/√Hz
pAp-p
f = 0.1Hz to 10Hz
GAIN
Gain Equation
Range of Gain
Gain Error
4 + 60kΩ/RG
✻
V/V
V/V
4
10,000
✻
✻
VO = –14V to +13.3V
G = 4
±0.01
±0.03
±0.05
±0.1
±0.075
±0.3
±0.5
✻
✻
✻
✻
±0.1
±0.5
±1
%
%
%
%
G = 10
G = 100
G = 500
Gain vs Temperature
Nonlinearity
G = 4
G > 4(1)
VO = –14V to +13.3V
G = 4
±1
±25
±15
±100
✻
✻
✻
✻
ppm/°C
ppm/°C
±0.0004
±0.0004
±0.001
±0.002
±0.002
±0.002
±0.01
✻
✻
✻
✻
±0.004
±0.004
✻
% of FS
% of FS
% of FS
% of FS
G = 10
G = 100
G = 500
OUTPUT
Voltage: Positive
Negative
Load Capacitance Stability
Short-Circuit Current
(V+)–1.7 (V+)–0.9
✻
✻
✻
✻
✻
✻
V
V
pF
mA
(V–)+1
(V–)+0.4
1000
–9/+12
VOLTAGE REFERENCE
Accuracy
vs Temperature
vs Power Supply, V+
vs Load
Dropout Voltage, (V+) – VREF
Bandgap Voltage Reference
Accuracy
VREF = +2.5V, +5V, +10V
IL = 0
±0.15
±18
±20
3
±0.5
±35
±50
75
✻
✻
✻
✻
✻
✻
✻
✻
±1
±100
±100
✻
%
ppm/°C
ppm/V
ppm/mA
V
V
%
ppm/°C
IL = 0
V+ = (VREF + 1.25V) to +36V
IL = 0 to 5mA
(2)
Ref Load = 2kΩ
1.25
1
✻
1.24
±0.5
±18
IL = 0
IL = 0
vs Temperature
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.
®
2
INA125
SPECIFICATIONS: VS = ±15V (CONT)
At TA = +25°C, VS = ±15V, IA common = 0V, VREF common = 0V, and RL = 10kΩ, unless otherwise noted.
INA125P, U
INA125PA, UA
TYP
PARAMETER CONDITIONS
MIN
TYP
MAX
MIN
MAX
UNITS
FREQUENCY RESPONSE
Bandwidth, –3dB
G = 4
G = 10
G = 100
G = 500
150
45
4.5
0.9
0.2
60
✻
✻
✻
✻
✻
✻
✻
✻
✻
✻
kHz
kHz
kHz
kHz
V/µs
µs
µs
µs
µs
µs
Slew Rate
Settling Time, 0.01%
G = 4, 10V Step
G = 4, 10V Step
G = 10, 10V Step
G = 100, 10V Step
G = 500, 10V Step
50% Overdrive
83
375
1700
5
Overload Recovery
POWER SUPPLY
Specified Operating Voltage
Specified Voltage Range
Quiescent Current, Positive
Negative
Reference Ground Current(3)
Sleep Current (VSLEEP ≤ 100mV)
±15
✻
V
V
µA
µA
µA
µA
±1.35
±18
525
–325
✻
✻
✻
✻
IO = IREF = 0mA
IO = IREF = 0mA
460
–280
180
±1
✻
✻
✻
✻
RL = 10kΩ, Ref Load = 2kΩ
±25
✻
SLEEP MODE PIN(4)
VIH (Logic high input voltage)
VIL (Logic low input voltage)
+2.7
0
V+
+0.1
✻
✻
✻
✻
V
V
I
IH (Logic high input current)
15
0
150
✻
✻
✻
µA
µA
µs
IIL (Logic low input current)
Wake-up Time(5)
TEMPERATURE RANGE
Specification Range
Operation Range
–40
–55
–55
+85
+125
+125
✻
✻
✻
✻
✻
✻
°C
°C
°C
Storage Range
Thermal Resistance, θJA
16-Pin DIP
SO-16 Surface-Mount
80
100
✻
✻
°C/W
°C/W
✻ Specification same as INA125P, U.
NOTES: (1) Temperature coefficient of the "Internal Resistor" in the gain equation. Does not include TCR of gain-setting resistor, RG. (2) Dropout voltage is the
positive supply voltage minus the reference voltage that produces a 1% decrease in reference voltage. (3) VREFCOM pin. (4) Voltage measured with respect to
Reference Common. Logic low input selects Sleep mode. (5) IA and Reference, see Typical Performance Curves.
SPECIFICATIONS: VS = +5V
At TA = +25°C, VS = +5V, IA common at VS/2, VREF common = VS /2, VCM = VS/2, and RL = 10kΩ to VS/2, unless otherwise noted.
INA125P, U
TYP
INA125PA, UA
TYP
PARAMETER
CONDITIONS
MIN
MAX
MIN
MAX
UNITS
INPUT
Offset Voltage, RTI
Initial
vs Temperature
vs Power Supply
Input Voltage Range
Common-Mode Rejection
±75
±0.25
3
±500
✻
✻
✻
✻
±750
µV
µV/°C
µV/V
VS = +2.7V to +36V
20
50
See Text
V
CM = +1.1V to +3.6V
G = 4
78
86
100
100
84
94
114
114
72
80
90
90
✻
✻
✻
✻
dB
dB
dB
dB
G = 10
G = 100
G = 500
GAIN
Gain Error
VO = +0.3V to +3.8V
G = 4
±0.01
✻
%
OUTPUT
Voltage, Positive
Negative
(V+)–1.2 (V+)–0.8
(V–)+0.3 (V–)+0.15
✻
✻
✻
✻
V
V
POWER SUPPLY
Specified Operating Voltage
Operating Voltage Range
Quiescent Current
+5
✻
V
V
µA
µA
+2.7
460
±1
+36
525
±25
✻
✻
✻
✻
IO = IREF = 0mA
RL = 10kΩ, Ref Load = 2kΩ
✻
✻
Sleep Current (VSLEEP ≤ 100mV)
✻ Specification same as INA125P, U.
®
3
INA125
PIN CONFIGURATION
ABSOLUTE MAXIMUM RATINGS(1)
Top View
16-Pin DIP, SO-16
Power Supply Voltage, V+ to V– ........................................................ 36V
Input Signal Voltage .......................................................................... ±40V
Output Short Circuit ................................................................. Continuous
Operating Temperature ................................................. –55°C to +125°C
Storage Temperature..................................................... –55°C to +125°C
Lead Temperature (soldering, 10s) ............................................... +300°C
V+
SLEEP
V–
1
2
3
4
5
6
7
8
16 VREF10
15 VREF
5
NOTE: Stresses above these ratings may cause permanent damage.
14 VREF2.5
13 VREFBG
VREFOUT
IAREF
PACKAGE INFORMATION
VREFCOM
Sense
VO
12
11
10
9
PACKAGE DRAWING
+
VIN
PRODUCT
PACKAGE
NUMBER(1)
–
VIN
INA125PA
INA125P
16-Pin Plastic DIP
16-Pin Plastic DIP
180
180
RG
RG
INA125UA
INA125U
SO-16 Surface-Mount
SO-16 Surface-Mount
265
265
NOTES: (1) For detailed drawing and dimension table, please see end of data
sheet, or Appendix C of Burr-Brown IC Data Book.
ELECTROSTATIC
DISCHARGE SENSITIVITY
This integrated circuit can be damaged by ESD. Burr-Brown
recommends that all integrated circuits be handled with ap-
propriate precautions. Failure to observe proper handling and
installation procedures can cause damage.
ESD damage can range from subtle performance degradation
to complete device failure. Precision integrated circuits may
be more susceptible to damage because very small parametric
changes could cause the device not to meet its published
specifications.
®
4
INA125
TYPICAL PERFORMANCE CURVES
At TA = +25°C and VS = ±15V, unless otherwise noted.
GAIN vs FREQUENCY
COMMON-MODE REJECTION vs FREQUENCY
G = 100, 500
60
120
100
80
60
40
20
0
G = 500
50
G = 100
40
G = 10
30
G = 500
G = 4
G = 10
20
G = 100
G = 4
10
0
1
10
100
1k
10k
100k
1M
1
10
100
1k
10k
100k
1M
Frequency (Hz)
Frequency (Hz)
POSITIVE POWER SUPPLY REJECTION
vs FREQUENCY
NEGATIVE POWER SUPPLY REJECTION
vs FREQUENCY
140
120
100
80
120
100
80
60
40
20
0
G = 500
G = 100
G = 100
G = 500
G = 4
60
G = 10
G = 10
40
G = 4
20
1
10
100
1k
Frequency (Hz)
10k
100k
1M
1
10
100
1k
Frequency (Hz)
10k
100k
1M
INPUT COMMON-MODE VOLTAGE
vs OUTPUT VOLTAGE, VS = ±15V
INPUT COMMON-MODE VOLTAGE
vs OUTPUT VOLTAGE, VS = ±5V
15
10
5
5
IAREF = 0V
4
3
2
VS = +5V
+15V
+
VD/2
–
1
VO
+
–
0
0
VD/2
IAREF
+
–1
–2
–3
–4
–5
VCM
–5
–10
–15
–15V
VS = ±5V
–15
–10
–5
0
5
10
15
–5
–4 –3
–2
–1
0
1
2
3
4
5
Output Voltage (V)
Output Voltage (V)
®
5
INA125
TYPICAL PERFORMANCE CURVES (CONT)
At TA = +25°C and VS = ±15V, unless otherwise noted.
INPUT-REFERRED VOLTAGE AND CURRENT NOISE
vs FREQUENCY
SETTLING TIME vs GAIN
10k
1k
1k
100
10
1k
100
10
1
Current Noise
0.01%
0.1%
Voltage Noise
100
10
1
1
10
100
1k
1
10
100
1k
10k
100k
Gain (V/V)
Frequency (Hz)
INPUT-REFERRED OFFSET VOLTAGE
vs SLEEP TURN-ON TIME
QUIESCENT CURRENT AND SLEEP CURRENT
vs TEMPERATURE
100
80
550
500
450
400
350
300
250
200
150
100
50
60
G = 100
+IQ
40
20
0
±ISLEEP
–IQ
–20
–40
–60
–80
–100
VSLEEP = 100mV
+ISLEEP
V
SLEEP = 0V
0
–ISLEEP
100 125
–50
0
50
100
150
200
250
–75
–50
–25
0
25
50
75
Time From Turn-On (µs)
Temperature (°C)
INPUT BIAS AND OFFSET CURRENT
vs TEMPERATURE
SLEW RATE vs TEMPERATURE
0.30
0.25
0.20
0.15
0.10
0.05
0
16
14
12
10
8
IB
6
4
IOS
2
0
–75
–50
–25
0
25
50
75
100
125
–75
–50
–25
0
25
50
75
100
125
Temperature (°C)
Temperature (°C)
®
6
INA125
TYPICAL PERFORMANCE CURVES (CONT)
At TA = +25°C and VS = ±15V, unless otherwise noted.
LARGE-SIGNAL RESPONSE
SMALL-SIGNAL RESPONSE
G = 4
G = 4
G = 100
G = 100
100µs/div
100µs/div
INPUT BIAS CURRENT
INPUT-REFERRED NOISE, 0.1Hz to 10Hz
vs INPUT OVERLOAD VOLTAGE
200
160
120
80
All Gains
40
0
–40
–80
–120
–160
–200
–40
0
40
1µs/div
Overload Voltage (V)
OUTPUT VOLTAGE SWING
vs OUTPUT CURRENT
DELTA VOS vs REFERENCE CURRENT
V+
(V+)–1
(V+)–2
(V+)–3
(V+)–4
(V+)–5
25
20
15
10
5
+75°C
+25°C
+125°C
Sinking
–55°C
(V–)+5
(V–)+4
(V–)+3
(V–)+2
(V–)+1
V–
+75°C
Sourcing
–55°C
0
+125°C
+25°C
–5
0
±2
±4
±6
±8
±10
–8
–6
–4
–2
0
2
4
6
8
Output Current (mA)
Reference Current (mA)
®
7
INA125
TYPICAL PERFORMANCE CURVES (CONT)
At TA = +25°C and VS = ±15V, unless otherwise noted.
INPUT-REFERRED OFFSET VOLTAGE
PRODUCTION DISTRIBUTION, VS = ±15V
INPUT-REFERRED OFFSET VOLTAGE
PRODUCTION DISTRIBUTION, VS = +5V
30
25
20
15
10
5
35
30
25
20
15
10
5
Typical production
distribution of
packaged units.
Typical production
distribution of
packaged units.
0.1%
0.1%
0.02%
0.02%
0.1%
0.1%
0.05%
0.02%
0
0
Input-Referred Offset Voltage (µV)
Input-Referred Offset Voltage (µV)
VOLTAGE REFERENCE DRIFT
PRODUCTION DISTRIBUTION
INPUT-REFERRED OFFSET VOLTAGE DRIFT
PRODUCTION DISTRIBUTION
100
90
80
70
60
50
40
30
20
10
0
Typical production
distribution of packaged units.
Typical production
distribution of packaged units.
90
80
70
60
50
40
30
20
10
0
VS = ±15V or +5V
0.3%
0.2%
0.05%
Voltage Reference Drift (ppm/°C)
Input-Referred Offset Voltage Drift (µV/°C)
REFERENCE TURN-ON SETTLING TIME
REFERENCE VOLTAGE DEVIATION
vs TEMPERATURE
15
12
9
50
VREF = VBG, 2.5V, 5V, or 10V
0
–50
6
4
0
–3
–6
–9
–100
–150
–200
VREF = 10V
VREF = 5V
–12
–15
VREF = 2.5V
0
10
20
30
40
50
–75
–50
–25
0
25
50
75
100
125
Time From Power Supply Turn-On (µs)
Temperature (°C)
®
8
INA125
TYPICAL PERFORMANCE CURVES (CONT)
At TA = +25°C and VS = ±15V, unless otherwise noted.
0.1Hz to 10Hz REFERENCE NOISE
VREF = 2.5V, CL = 100pF
REFERENCE TRANSIENT RESPONSE
VREF = 2.5V, CL = 100pF
+1mA
0mA
–1mA
1µs/div
10µs/div
NEGATIVE REFERENCE AC LINE REJECTION
vs FREQUENCY
POSITIVE REFERENCE AC LINE REJECTION
vs FREQUENCY
120
100
80
60
40
20
0
120
100
80
60
40
20
0
VREF = 2.5V
VREF = 2.5V
VREF = 5V
VREF = 5V
VREF = 10V
VREF = 10V
C = 0.01µF
C = 0.1µF
Capacitor connected between
VREFOUT and VREFCOM.
1
10
100
1k
Frequency (Hz)
10k
100k
1M
1
10
100
1k
10k
100k
1M
Frequency (Hz)
®
9
INA125
For example, in Figure 1 VREFOUT is connected to VREF10
thus supplying 10V to the bridge. It is recommended that
VREFOUT be connected to one of the reference voltage pins
even when the reference is not being utilized to avoid
saturating the reference amplifier. Driving the SLEEP pin
LOW puts the INA125 in a shutdown mode.
APPLICATION INFORMATION
Figure 1 shows the basic connections required for operation
of the INA125. 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 instrumentation amplifier refer-
ence (IAREF) terminal which is normally grounded. This
must be a low impedance connection to assure good com-
mon-mode rejection. A resistance of 12Ω in series with the
IAREF pin will cause a typical device to degrade to approxi-
mately 80dB CMR (G = 4).
SETTING THE GAIN
Gain of the INA125 is set by connecting a single external
resistor, RG, between pins 8 and 9:
(1)
60kΩ
G = 4 +
RG
Connecting VREFOUT (pin 4) to one of the four available
reference voltage pins (VREFBG, VREF2.5, VREF5, or VREF10)
provides an accurate voltage source for bridge applications.
Commonly used gains and RG resistor values are shown in
Figure 1.
V+
SLEEP(1)
0.1µF
1
2
INA125
V
REFCOM
12
13
14
DESIRED GAIN
(V/V)
RG
(Ω)
NEAREST 1%
RG VALUE (Ω)
R(2)
4
5
10
20
50
100
200
500
1000
2000
10000
NC
60k
10k
3750
1304
625
306
121
60
NC
60.4k
10k
3740
1300
619
309
121
60.4
30.1
6.04
V
REFBG
R
VREF2.5
2R
15
V
REF5
30
6
4R
VREF10
16
4
NC: No Connection.
Ref
Amp
Bandgap
VREF
+
–
V
REFOut
VO = (VIN – VIN) G
10V
G = 4 + 60kΩ
RG
+
VIN
10
6
9
A1
30kΩ
11
Sense
+
10kΩ
RG
10kΩ
Load
VO
8
7
A2
–
VIN
30kΩ
IAREF
–
5
3
NOTE: (1) SLEEP pin should be connected
to V+ if shutdown function is not being used.
(2) Nominal value of R is 21kΩ, ±25%.
0.1µF
V–
FIGURE 1. Basic Connections.
®
10
INA125
The 60kΩ term in equation 1 comes from the internal metal
film resistors which are laser trimmed to accurate absolute
values. The accuracy and temperature coefficient of these
resistors are included in the gain accuracy and drift specifi-
cations of the INA125.
INPUT COMMON-MODE RANGE
The input common-mode range of the INA125 is shown in
the typical performance curves. The common-mode range is
limited on the negative side by the output voltage swing of
A2, an internal circuit node that cannot be measured on an
external pin. The output voltage of A2 can be expressed as:
The stability and temperature drift of the external gain
setting resistor, RG, also affects gain. RG’s contribution to
gain accuracy and drift can be directly inferred from the gain
equation (1). Low resistor values required for high gain can
make wiring resistance important. Sockets add to the wiring
resistance, which will contribute additional gain error (pos-
sibly an unstable gain error) in gains of approximately 100
or greater.
+
–
–
V02 = 1.3VIN – (VIN – VIN) (10kΩ/RG)
(voltages referred to IAREF terminal, pin 5)
The internal op amp A2 is identical to A1. Its output swing
is limited to approximately 0.8V from the positive supply
and 0.25V from the negative supply. When the input com-
mon-mode range is exceeded (A2’s output is saturated), A1
can still be in linear operation, responding to changes in the
non-inverting input voltage. The output voltage, however,
will be invalid.
OFFSET TRIMMING
The INA125 is laser trimmed for low offset voltage and
offset voltage drift. Most applications require no external
offset adjustment. Figure 2 shows an optional circuit for
trimming the output offset voltage. The voltage applied to
the IAREF terminal is added to the output signal. The op amp
buffer is used to provide low impedance at the IAREF
terminal to preserve good common-mode rejection.
PRECISION VOLTAGE REFERENCE
The on-board precision voltage reference provides an accu-
rate voltage source for bridge and other transducer applica-
tions or ratiometric conversion with analog-to-digital con-
verters. A reference output of 2.5V, 5V or 10V is available
by connecting VREFOUT (pin 4) to one of the VREF pins
(VREF2.5, VREF5, or VREF10). Reference voltages are laser-
trimmed for low inital error and low temperature drift.
Connecting VREFOUT to VREFBG (pin 13) produces the
bandgap reference voltage (1.24V ±0.5%) at the reference
output.
–
VIN
V+
VO
RG
INA125
100µA
IAREF
1/2 REF200
+
VIN
Positive supply voltage must be 1.25V above the desired
reference voltage. For example, with V+ = 2.7V, only the
1.24V reference (VREFBG) can be used. If using dual sup-
plies VREFCOM can be connected to V–, increasing the
100Ω
100Ω
10kΩ
OPA237
±10mV
Adjustment Range
100µA
Microphone,
1/2 REF200
Hydrophone
etc.
INA125
V–
FIGURE 2. Optional Trimming of Output Offset Voltage.
47kΩ
47kΩ
INPUT BIAS CURRENT RETURN
The input impedance of the INA125 is extremely high—
approximately 1011Ω. However, a path must be provided for
the input bias current of both inputs. This input bias current
flows out of the device and is approximately 10nA. High
input impedance means that this input bias current changes
very little with varying input voltage.
Thermocouple
INA125
10kΩ
Input circuitry must provide a path for this input bias current
for proper operation. Figure 3 shows various provisions for
an input bias current path. Without a bias current path, the
inputs will float to a potential which exceeds the common-
mode range, and the input amplifiers will saturate.
INA125
If the differential source resistance is low, the bias current
return path can be connected to one input (see the thermo-
couple example in Figure 3). With higher source impedance,
using two equal resistors provides a balanced input with
possible advantages of lower input offset voltage due to bias
current and better high frequency common-mode rejection.
Center-tap provides
bias current return.
FIGURE 3. Providing an Input Common-Mode Current Path.
®
11
INA125
amount of supply voltage headroom available to the refer-
ence. Approximately 180µA flows out of the VREFCOM
terminal, therefore, it is recommended that it be connected
through a low impedance path to sensor common to avoid
possible ground loop problems.
A transition region exists when VSLEEP is between 400mV
and 2.7V (with respect to VREFCOM) where the output is
unpredictable. Operation in this region is not recommended.
The INA125 achieves high accuracy quickly following wake-
up (VSLEEP ≥ 2.7V). See the typical performance curve
“Input-Referred Offset Voltage vs Sleep Turn-on Time.” If
shutdown is not being used, connect the SLEEP pin to V+.
Reference noise is proportional to the reference voltage
selected. With VREF = 2.5V, 0.1Hz to 10Hz peak-to-peak
noise is approximately 9µVp-p. Noise increases to 36µVp-p
for the 10V reference. Output drive capability of the voltage
reference is improved by connecting a transistor as shown in
Figure 4. The external transistor also serves to remove power
from the INA125.
LOW VOLTAGE OPERATION
The INA125 can be operated on power supplies as low as
±1.35V. Performance remains excellent with power sup-
plies ranging from ±1.35V to ±18V. Most parameters vary
only slightly throughout this supply voltage range—see
typical performance curves. Operation at very low supply
voltage requires careful attention to ensure that the com-
mon-mode voltage remains within its linear range. See
“Input Common-Mode Voltage Range.” As previously men-
tioned, when using the on-board reference with low supply
voltages, it may be necessary to connect VREFCOM to V– to
ensure VS – VREF ≥ 1.25V.
Internal resistors that set the voltage reference output are
ratio-trimmed for accurate output voltages (±0.5% max). The
absolute resistance values, however, may vary ±25%. Adjust-
ment of the reference output voltage with an external resistor
is not recommended because the required resistor value is
uncertain.
INA125
V
REFCOM
SINGLE SUPPLY OPERATION
12
13
14
The INA125 can be used on single power supplies of +2.7V
to +36V. Figure 5 shows a basic single supply circuit. The
IAREF, VREFCOM, and V– terminals are connected to ground.
Zero differential input voltage will demand an output volt-
age of 0V (ground). When the load is referred to ground as
shown, actual output voltage swing is limited to approxi-
mately 150mV above ground. The typical performance curve
“Output Voltage Swing vs Output Current” shows how the
output swing varies with output current.
V
REFBG
VREF2.5
15
16
VREF
5
With single supply operation, careful attention should be
paid to input common-mode range, output voltage swing of
both op amps, and the voltage applied to the IAREF terminal.
VIN+ and VIN– must both be 1V above ground for linear
operation. You cannot, for instance, connect the inverting
input to ground and measure a voltage connected to the non-
inverting input.
VREF10
V+
4
Ref
Amp
TIP29C
Bandgap
VREF
VREFOut
10V
to load
(transducer)
+3V
+3V
FIGURE 4. Reference Current Boost.
1.5V – ∆V
SHUTDOWN
VO
RG
INA125
1000Ω
12
The INA125 has a shutdown option. When the SLEEP pin
is LOW (100mV or less), the supply current drops to
approximately 1µA and output impedance becomes approxi-
mately 80kΩ. Best performance is achieved with CMOS
logic. To maintain low sleep current at high temperatures,
5
3
RL
1.5V + ∆V
V
SLEEP should be as close to 0V as possible. This should not
be a problem if using CMOS logic unless the CMOS gate is
driving other currents. Refer to the typical performance
curve, “Sleep Current vs Temperature.”
FIGURE 5. Single Supply Bridge Amplifier.
®
12
INA125
INPUT PROTECTION
The inputs of the INA125 are individually protected for
voltage up to ±40V. For example, a condition of –40V on
one input and +40V on the other input will not cause
damage. Internal circuitry on each input provides low series
impedance under normal signal conditions. To provide
equivalent protection, series input resistors would contribute
excessive noise. If the input is overloaded, the protection
circuitry limits the input current to a safe value of approxi-
mately 120µA to 190µA. The typical performance curve
“Input Bias Current vs Input Overload Voltage” shows this
input current limit behavior. The inputs are protected even if
the power supplies are disconnected or turned off.
+5V
1
SLEEP
2
INA125
V
REFCOM
12
13
14
V
REFBG
V
REF2.5
15
16
4
V
REF5
VREF10
Ref
Amp
Bandgap
VREF
2.5V
+
VIN
10
11
6
9
A1
30kΩ
+
Sense
10kΩ
RG
10kΩ
60kΩ
Load
VO = +2.5V +
[
(
VI+N – VI–N) (4 +
)]
RG
8
7
A2
–
VIN
30kΩ
IAREF
5
–
3
2.5V(1)
(Psuedoground)
NOTE: (1) “Psuedoground” is at +2.5V above actual ground.
This provides a precision reference voltage for succeeding
single-supply op amp stages.
FIGURE 6. Psuedoground Bridge Measurement, 5V Single Supply.
®
13
INA125
PACKAGE OPTION ADDENDUM
www.ti.com
7-Oct-2021
PACKAGING INFORMATION
Orderable Device
Status Package Type Package Pins Package
Eco Plan
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
Samples
Drawing
Qty
(1)
(2)
(3)
(4/5)
(6)
INA125P
ACTIVE
ACTIVE
PDIP
PDIP
N
N
16
16
25
25
RoHS & Green
RoHS & Green
Call TI
N / A for Pkg Type
N / A for Pkg Type
-40 to 85
INA125P
INA125PA
Call TI
Call TI
Call TI
Call TI
Call TI
Call TI
INA125P
A
INA125PAG4
INA125U
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
PDIP
SOIC
SOIC
SOIC
SOIC
N
D
D
D
D
16
16
16
16
16
25
40
RoHS & Green
RoHS & Green
N / A for Pkg Type
Level-3-260C-168 HR
Level-3-260C-168 HR
Level-3-260C-168 HR
Level-3-260C-168 HR
INA125P
A
INA125U
A
INA125U/2K5
INA125UA
2500 RoHS & Green
40 RoHS & Green
2500 RoHS & Green
INA125U
A
INA125U
A
INA125UA/2K5
INA125U
A
(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 <=1000ppm threshold. Antimony trioxide based
flame retardants must also meet the <=1000ppm threshold requirement.
(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
Addendum-Page 1
PACKAGE OPTION ADDENDUM
www.ti.com
7-Oct-2021
(6)
Lead finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two
lines if the finish value exceeds the maximum column width.
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.
Addendum-Page 2
PACKAGE MATERIALS INFORMATION
www.ti.com
3-Jun-2022
TAPE AND REEL INFORMATION
REEL DIMENSIONS
TAPE DIMENSIONS
K0
P1
W
B0
Reel
Diameter
Cavity
A0
A0 Dimension designed to accommodate the component width
B0 Dimension designed to accommodate the component length
K0 Dimension designed to accommodate the component thickness
Overall width of the carrier tape
W
P1 Pitch between successive cavity centers
Reel Width (W1)
QUADRANT ASSIGNMENTS FOR PIN 1 ORIENTATION IN TAPE
Sprocket Holes
Q1 Q2
Q3 Q4
Q1 Q2
Q3 Q4
User Direction of Feed
Pocket Quadrants
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
SPQ
Reel
Reel
A0
B0
K0
P1
W
Pin1
Diameter Width (mm) (mm) (mm) (mm) (mm) Quadrant
(mm) W1 (mm)
INA125U/2K5
SOIC
SOIC
D
D
16
16
2500
2500
330.0
330.0
16.4
16.4
6.5
6.5
10.3
10.3
2.1
2.1
8.0
8.0
16.0
16.0
Q1
Q1
INA125UA/2K5
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
3-Jun-2022
TAPE AND REEL BOX DIMENSIONS
Width (mm)
H
W
L
*All dimensions are nominal
Device
Package Type Package Drawing Pins
SPQ
Length (mm) Width (mm) Height (mm)
INA125U/2K5
SOIC
SOIC
D
D
16
16
2500
2500
356.0
356.0
356.0
356.0
35.0
35.0
INA125UA/2K5
Pack Materials-Page 2
PACKAGE MATERIALS INFORMATION
www.ti.com
3-Jun-2022
TUBE
T - Tube
height
L - Tube length
W - Tube
width
B - Alignment groove width
*All dimensions are nominal
Device
Package Name Package Type
Pins
SPQ
L (mm)
W (mm)
T (µm)
B (mm)
INA125P
INA125PA
INA125PAG4
INA125U
N
N
N
D
D
PDIP
PDIP
PDIP
SOIC
SOIC
16
16
16
16
16
25
25
25
40
40
506
506
13.97
13.97
13.97
8
11230
11230
11230
3940
4.32
4.32
4.32
4.32
4.32
506
506.6
506.6
INA125UA
8
3940
Pack Materials-Page 3
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