1
INA146
INA146
1999 Burr-Brown Corporation
PDS-1491A
Printed in U.S.A. September, 1999
High-Voltage, Programmable Gain
DIFFERENCE AMPLIFIER
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
For most current data sheet and other product
information, visit www.burr-brown.com
INA146
DESCRIPTION
The INA146 is a precision difference amplifier that
can be used to accurately attenuate high differential
voltages and reject high common-mode voltages for
compatibility with common signal processing voltage
levels. High-voltage capability also affords inherent
input protection. The input common-mode range ex-
tends beyond both supply rails, making the INA146
well-suited for both single and dual supply applica-
tions.
On-chip precision resistors are laser-trimmed to achieve
accurate gain and high common-mode rejection. Ex-
cellent TCR tracking of these resistors assures contin-
ued high precision over temperature.
A 10:1 difference amplifier provides 0.1V/V gain
when the output amplifier is used as a unity-gain
buffer. In this configuration, input voltages up to
100V can be measured. Gains greater than 0.1V/V
can be set with an external resistor pair without affect-
ing the common-mode input range.
The INA146 is available in the SO-8 surface-mount
package specified for the extended industrial tempera-
ture range, 40
C to +85
C.
FEATURES
q
HIGH COMMON-MODE VOLTAGE:
+40V at V
S
= +5V
100V at V
S
=
15V
q
DIFFERENTIAL GAIN = 0.1V/V TO 100V/V:
Set with External Resistors
q
LOW QUIESCENT CURRENT: 570
A
q
WIDE SUPPLY RANGE:
Single Supply: 4.5V to 36V
Dual Supplies:
2.25V to
18V
q
LOW GAIN ERROR: 0.025%
q
HIGH CMR: 80dB
q
SO-8 PACKAGE
APPLICATIONS
q
CURRENT SHUNT MEASUREMENTS
q
SENSOR AMPLIFIER
q
SYNCHRONOUS DEMODULATOR
q
CURRENT AND DIFFERENTIAL LINE
RECEIVER
q
VOLTAGE-CONTROLLED CURRENT
SOURCE
q
BATTERY POWERED SYSTEMS
q
LOW COST AUTOMOTIVE
INSTRUMENTATION
R
5
10k
(1%)
A1
V
IN
INA146
V
O
R
2
10k
R
1
100k
V
IN
R
3
100k
R
4
10k
R
G1
R
G2
A2
V
01
Ref
V
V+
G = 0.1
+
2
5
7
4
1
8
6
3
V
O
= (V
IN
V
IN
) 0.1 (1 + R
G2
/R
G1
)
+
2
INA146
SPECIFICATIONS: V
S
=
2.25V to
18V Dual Supplies
At T
A
= +25
C, G = 0.1, R
L
= 10k
connected to ground and ref pin connected to ground unless otherwise noted.
Boldface limits apply over the specified temperature range, T
A
= 40
C to +85
C.
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.
INA146UA
PARAMETER
CONDITION
MIN
TYP
MAX
UNITS
OFFSET VOLTAGE, V
O
RTI
(1, 2)
Input Offset Voltage
V
OS
V
S
=
15, V
CM
= V
O
= 0V
1
5
mV
vs Temperature
V
OS
/
T
See Typical Curve
vs Power Supply
PSRR
V
S
=
1.35V to
18V
100
600
V/ V
vs Time
3
V/mo
Offset Voltage, V
01
RTI
(1, 2)
1
mV
INPUT VOLTAGE RANGE
Common-Mode Voltage Range
V
CM
(V
IN
+) (V
IN
) = 0V, V
O
= 0V
100
(3)
V
Common-Mode Rejection
CMRR
V
CM
= 11 (V) to 11 (V+) = 11, R
S
= 0
70
80
dB
Over Temperature
64
74
dB
INPUT BIAS CURRENT
(2)
V
CM
= V
S
/2
Bias Current
I
B
50
nA
Offset Current
I
OS
5
nA
INPUT IMPEDANCE
Differential (non-inverting input)
110
k
Differential (inverting input)
91.7
k
Common-Mode
55
k
NOISE
RTI
(1, 4)
Voltage Noise, f = 0.1Hz to 10Hz
10
Vp-p
Voltage Noise Density, f = 1kHz
e
n
550
nV/
Hz
GAIN
G = 0.1 to 100
Gain Equation
G = 0.1 (1 + R
G2
/ R
G1
)
V/ V
Initial
(1)
0.1
V/V
Gain Error
R
L
= 100k
, V
O
= (V)+0.15 to (V+)1, G = 1
0.025
0.1
%
vs Temperature
R
L
= 100k
, V
O
= (V)+0.25 to (V+)1, G = 1
1
10
ppm /
C
R
L
= 10k
, V
O
= (V)+0.3 to (V+)1.25, G = 1
0.025
0.1
%
vs Temperature
R
L
= 10k
, V
O
= (V)+0.5 to (V+)1.25, G = 1
1
10
ppm /
C
Nonlinearity
V
O
= (V)+0.3 to (V+)1.25, G = 1
0.001
0.01
% of FS
FREQUENCY RESPONSE
Small Signal Bandwidth
G = 0.1
550
kHz
G = 1
50
kHz
Slew Rate
0.45
V/
s
Settling Time, 0.1%
G = 1, 10V Step
40
s
0.01%
G = 1, 10V Step
80
s
Overload Recovery
50% Input Overload
40
s
OUTPUT, V
O
Voltage Output
R
L
= 100k
, G = 1
(V) + 0.15
(V+) 1
V
Over Temperature
R
L
= 100k
, G = 1
(V) + 0.25
(V+) 1
V
R
L
= 10k
, G = 1
(V) + 0.3
(V+) 1.25
V
Over Temperature
R
L
= 10k
, G = 1
(V) + 0.5
(V+) 1.25
V
Short-Circuit Current
Continuous to Common
15
mA
Capacitive Load
Stable Operation
1000
pF
POWER SUPPLY
Specified Voltage Range, Dual Supplies
2.25
18
V
Operating Voltage Range
1.35
18
V
Quiescent Current
V
IN
= 0, I
O
= 0
570
700
A
Over Temperature
750
A
TEMPERATURE RANGE
Specified Range
40
+85
C
Operating Range
55
+125
C
Storage Range
55
+125
C
Thermal Resistance
JA
150
C/W
NOTES: (1) Overall difference amplifier configuration. Referred to input pins (V
IN
+ and V
IN
), gain = 0.1V/V. Specified with 10k
in feedback of A2. (2) Input offset
voltage specification includes effects of amplifier's input bias and offset currents. (3) Common-mode voltage range is 11 (V) to 11 [(V+) 1] with a maximum of
100V.
(4) Includes effects of input current noise and thermal noise contribution of resistor network.
3
INA146
SPECIFICATIONS: V
S
= +5V Single Supply
At T
A
= +25
C, G = 1, R
L
= 10k
connected to V
S
/2 and Ref pin connected to V
S
/2 unless otherwise noted.
Boldface limits apply over the specified temperature range, T
A
= 40
C to +85
C.
INA146UA
PARAMETER
CONDITION
MIN
TYP
MAX
UNITS
OFFSET VOLTAGE, V
O
RTI
(1, 2)
Input Offset Voltage
V
OS
V
CM
= V
O
= 0V
3
10
mV
vs Temperature
V
OS
/
T
See Typical Curve
vs Power Supply Rejection Ratio
PSRR
V
S
=
1.35V to
18V
100
600
V/
C
vs Time
3
V/mo
INPUT VOLTAGE RANGE
Common-Mode Voltage Range
V
CM
V
IN
+ V
IN
= 0V, V
O
= 0V
25
19
V
Common-Mode Rejection Ratio
CMRR
V
CM
= 25V to +19V, R
S
= 0
70
80
dB
Over Temperature
64
74
dB
INPUT BIAS CURRENT
(2)
Bias Current
I
B
50
nA
Offset Current
I
OS
5
nA
INPUT IMPEDANCE
Differential (non-inverting input)
110
k
Differential (inverting input)
91.7
k
Common-Mode
55
k
NOISE
RTI
(1, 3, 4)
Voltage Noise, f = 0.1Hz to 10Hz
10
Vp-p
Voltage Noise Density, f = 1kHz
e
n
550
nV/
Hz
GAIN
G = 0.1 to 100
V/V
Gain Equation
G = 0.1 (1 + R
G2
/ R
G1
)
V/ V
Initial
(1)
0.1
V/V
Gain Error
R
L
= 100k
, V
O
= 0.15V to 4V, G = 1
0.025
0.1
%
vs Temperature
R
L
= 100k
, V
O
= 0.25V to 4V, G = 1
1
10
ppm /
C
R
L
= 10k
, V
O
= 0.3V to 3.75V, G = 1
0.025
0.1
%
vs Temperature
R
L
= 10k
, V
O
= 0.5V to 3.75V, G = 1
1
10
ppm /
C
Nonlinearity
V
O
= +0.3 to +3.75, G = 1
0.001
0.01
% of FS
FREQUENCY RESPONSE
Small Signal Bandwidth
G = 0.1
550
kHz
G = 1
50
kHz
Slew Rate
0.45
V/
s
Settling Time, 0.1%
G = 1, 10V Step
40
s
0.01%
G = 1, 10V Step
80
s
Overload Recovery
50% Input Overload
40
s
OUTPUT, V
O
Voltage Output
R
L
= 100k
, G = 1
0.15
4
V
Over Temperature
R
L
= 100k
, G = 1
0.25
4
V
R
L
= 10k
, G = 1
0.3
3.75
V
Over Temperature
R
L
= 10k
, G = 1
0.5
3.75
V
Short-Circuit Current
Continuous to Common
15
mA
Capacitive Load
Stable Operation
1000
pF
POWER SUPPLY
Voltage Range, Dual Supplies
2.25
18
V
Voltage Range, Single Supply
4.5
36
V
Quiescent Current
V
IN
= 0, I
O
= 0
570
700
A
Over Temperature
750
A
TEMPERATURE RANGE
Specified Range
40
+85
C
Operating Range
55
+125
C
Storage Range
55
+125
C
Thermal Resistance
JA
150
C/W
NOTES: (1) Overall difference amplifier configuration. Referred to input pins (V
IN
+ and V
IN
), gain = 0.1V/V. Specified with 10k
in feedback of A2. (2) Input offset
voltage specification includes effects of amplifier's input bias and offset currents. (3) Includes effects of input current noise and thermal noise contribution of resistor
network. (4) Common-mode voltage range is 11 (V) to 11 [(V+) 1] with a maximum of
100V.
4
INA146
AMPLIFIER A1, A2 PERFORMANCE
At T
A
= +25
C, G = 0.1, R
L
= 10k
connected to ground and Ref pin, unless otherwise noted.
Boldface limits apply over the specified temperature range, T
A
= 40
C to +85
C.
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.
Supply Voltage, V+ to V .................................................................... 36V
Signal Input Terminals, Voltage ......................................................
100V
Current .......................................................
1mA
Output Short Circuit (to ground) .............................................. Continuous
Operating Temperature .................................................. 55
C to +125
C
Storage Temperature ..................................................... 55
C to +150
C
Junction Temperature .................................................................... +150
C
Lead Temperature (soldering, 10s) ............................................... +240
C
NOTE: (1) Stresses above these ratings may cause permanent damage.
Exposure to absolute maximum conditions for extended periods may degrade
device reliability.
ABSOLUTE MAXIMUM RATINGS
(1)
Top View
SO-8
PACKAGE
SPECIFIED
DRAWING
TEMPERATURE
PACKAGE
ORDERING
TRANSPORT
PRODUCT
PACKAGE
NUMBER(1)
RANGE
MARKING
NUMBER(2)
MEDIA
INA146UA
SO-8
182
40
C to +85
C
INA146UA
INA146UA
Rails
"
"
"
"
"
INA146UA/2K5
Tape and Reel
NOTES: (1) For detailed drawing and dimension table, please see end of data sheet, or Appendix C of Burr-Brown IC Data Book, or visit the Burr-Brown web site
at www.burr-brown.com. (2) 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 "INA146UA/2K5" will get a single 2500-piece Tape and Reel. For detailed Tape and Reel mechanical information, refer to Appendix B of
Burr-Brown IC Data Book.
PACKAGE/ORDERING INFORMATION
INA146UA
PARAMETER
CONDITION
MIN
TYP
MAX
UNITS
OFFSET VOLTAGE, V
O
RTI
(1, 2)
Input Offset Voltage
V
OS
V
S
=
15V, V
CM
= V
O
= 0V
0.5
mV
vs Temperature
V
OS
/
T
T
A
= 40
C to +85
C
1
V/
C
INPUT VOLTAGE RANGE
Common-Mode Voltage Range
V
CM
V
IN
+ V
IN
= 0V, V
O
= 0V
(V) to (V+) 1
V
Common-Mode Rejection Ratio
CMRR
V
CM
= (V) to (V+) 1
90
dB
OPEN-LOOP GAIN
Open Loop Gain
A
OL
110
dB
INPUT BIAS CURRENT
(2)
Bias Current
I
B
50
nA
Offset Current
I
OS
5
nA
RESISTOR AT A1 OUTPUT, V
O1
Initial
10
k
Error
1
%
Temperature Drift Coefficient
100
ppm/
C
Ref
V
IN
V
IN
V
+
V
O1
V+
V
O
R
G
1
2
3
4
8
7
6
5
5
INA146
TYPICAL PERFORMANCE CURVES
At T
A
= +25
C, V
S
=
15V, G = 0.1, R
L
= 10k
connected to ground and Ref pin connected to ground, unless otherwise noted.
0.1Hz to 10Hz VOLTAGE NOISE (RTI)
500ms/div
2
V/div
GAIN vs FREQUENCY
Frequency (Hz)
Voltage Gain (dB)
100
1K
10K
1M
10M
40
20
0
20
40
100K
V
S
=
15V
C
L
= 1000pF
G = 10
G = 1
G = 0.1
GAIN vs FREQUENCY
Frequency (Hz)
Voltage Gain (dB)
100
1K
10K
1M
10M
40
20
0
20
40
100K
V
S
=
15V
C
L
= 200pF
10k
G = 10
G = 0.1
G = 1
COMMON-MODE REJECTION vs FREQUENCY
Frequency (Hz)
Common-Mode Rejection (dB)
10
100
1k
1M
10M
100
80
60
40
20
0
10k
100k
POWER SUPPLY REJECTION vs FREQUENCY
Frequency (Hz)
Power Supply Rejection (dB)
1
10
100
10k
100k
100
80
60
40
20
0
1k
PSR+
(V
S
=
15V)
PSR
(V
S
=
15V)
PSR+
(V
S
= +5V)
INPUT VOLTAGE NOISE DENSITY
Frequency (Hz)
Input Voltage Noise (nV/
Hz
0.1
1
10
10k
100k
10k
1k
100
100
1k
G = 0.1
G = 1
G = 10
6
INA146
TYPICAL PERFORMANCE CURVES
(Cont.)
At T
A
= +25
C, V
S
=
15V, G = 0.1, R
L
= 10k
connected to ground and Ref pin connected to ground, unless otherwise noted.
QUIESCENT CURRENT AND
SHORT-CIRCUIT CURRENT vs TEMPERATURE
Temperature (
C)
I
Q
(
A)
60
40
0
20
80
100
I
SC
I
Q
120 140
670
650
630
610
590
570
550
530
510
490
470
I
SC
(mA)
20
18
16
14
12
10
8
6
4
2
0
20
60
40
G = 1
SLEW RATE vs TEMPERATURE
Temperature (
C)
Sew Rate (V/
s)
60
40
0
20
80
100
120 140
0.6
0.55
0.5
0.45
0.4
0.35
0.3
0.25
0.2
20
60
40
G = 1
GAIN AND PHASE vs FREQUENCY
Op Amp A1 and A2
Frequency (Hz)
Open-Loop Gain (dB)
Phase (
)
1
10
100
100k
1M
110
100
90
80
70
60
50
40
30
20
10
0
10
90
135
180
1k
10k
R
L
= 10k
|| 200pF
R
L
= 10k
|| 1nF
G
SETTLING TIME vs LOAD CAPACITANCE
Load Capacitance (nF)
Settling Time (
s)
1
3
30
100
120
100
80
60
40
20
0
10
0.01%, G = 1
T
S
vs C
LOAD
V
S
=
15V
0.1%, G = 0.1
0.1%, G = 1
+25
C
MAXIMUM OUTPUT VOLTAGE SWING
vs OUTPUT CURRENT
15
10
5
0
5
10
15
0
2
4
6
8
10
12
14
16
Output Current (mA)
Output Voltage Swing (V)
+85
C
25
C
+25
C
+85
C
+125
C
+85
C
55
C
+125
C
25
C
OFFSET VOLTAGE
PRODUCTION DISTRIBUTION
Percent of Amplifiers (%)
Offset Voltage, RTI (mV)
< 10
< 9
< 8
< 7
< 6
< 5
< 4
< 3
< 2
< 1
< 0
< 1
< 2
< 3
< 4
< 5
< 6
< 7
< 8
< 9
< 10
> 10
25
20
15
10
5
0
Typical production
distribution of
packaged units.
V
S
=
2.25V
7
INA146
TYPICAL PERFORMANCE CURVES
(Cont.)
At T
A
= +25
C, V
S
=
15V, G = 0.1, R
L
= 10k
connected to ground and Ref pin connected to ground, unless otherwise noted.
SMALL-SIGNAL STEP RESPONSE
(G = 0.1, R
L
= 10k
, C
L
= 200pF)
5
s/div
50mV/div
SMALL-SIGNAL STEP RESPONSE
(G = 0.1, C
L
= 1000pF)
5
s/div
50mV/div
SMALL-SIGNAL STEP RESPONSE
(G = 1, C
L
= 1000pF)
5
s/div
50mV/div
LARGE-SIGNAL STEP RESPONSE
(G = 1, R
L
= 10k
, C
L
= 200pF)
50
s/div
5V/div
OFFSET VOLTAGE
PRODUCTION DISTRIBUTION
Percent of Amplifiers (%)
Offset Voltage, RTI (mV)
< 10
< 9
< 8
< 7
< 6
< 5
< 4
< 3
< 2
< 1
< 0
< 1
< 2
< 3
< 4
< 5
< 6
< 7
< 8
< 9
< 10
> 10
40
35
30
25
20
15
10
5
0
Typical production
distribution of
packaged units.
V
S
=
15V
OFFSET VOLTAGE DRIFT
PRODUCTION DISTRIBUTION
Percent of Amplifiers (%)
Offset Voltage Drift, RTI (
V/
C)
100
90
80
70
60
50
40
30
20
10
0
10
20
30
40
50
60
70
80
90
100
30
25
20
15
10
5
0
Typical production
distribution of
packaged units.
V
S
=
15V
8
INA146
APPLICATION INFORMATION
The INA146 is a programmable gain difference amplifier
consisting of a gain of 0.1 difference amplifier and a pro-
grammable-gain output buffer stage. Basic circuit connec-
tions are shown in Figure 1. Power supply bypass capacitors
should be connected close to pins 4 and 7 as shown. The
amplifier is programmable in the range of G = 0.1 to G = 50
with two external resistors.
The output of A1 is connected to the noninverting input of
A2 through a 10k
resistor which is trimmed to
1%
absolute accuracy. The A2 input is available for applications
such as a filter or a precision current source. See application
figures for examples.
OPERATING VOLTAGE
The INA146 is fully specified for supply voltages from
2.25V to
18V with key parameters guaranteed over the
temperature range 40
C to +85
C. The INA146 can be
operated with single or dual supplies with excellent perfor-
mance. Parameters that vary significantly with operating
voltage, load conditions or temperature are shown in the
typical performance curves.
SETTING THE GAIN
The gain of the INA146 is set by using two external
resistors, R
G1
and R
G2
, according to the equation:
G = 0.1 (1 + R
G2
/ R
G1
)
For a total gain of 0.1, A2 is connected as a buffer amplifier
with no R
G1
. A feedback resistor, R
G2
= 10k
, should be
used in the buffer connection. This provides bias current
cancellation (in combination with internal R
5
) to assure
specified offset voltage performance. Commonly used val-
ues are shown in the table of Figure 1. Resistor values for
other gains should be chosen to provide a 10k
parallel
resistance.
COMMON-MODE RANGE
The 10:1 input resistor ratio of the INA146 provides an input
common-mode range that can extend well beyond the power
supply rails. Exact range depends on the power supply
voltage and the voltage applied to the Ref terminal (pin 1).
To assure proper operation, the voltage at the non-inverting
input of A1 (an internal node) must be within its linear
operating range. Its voltage is determined by the simple 10:1
voltage divider between pin 3 and pin 1. This voltage must
be between V and (V+) 1V.
FIGURE 1. Basic Circuit Connections.
R
5
10k
A1
V
IN
INA146
V
O
R
2
10k
R
1
100k
V
IN
R
3
100k
R
4
10k
R
G1
R
G2
R
B
A2
V
01
7
3
2
5
4
1
8
6
V
S
+V
S
0.1
F
+
V
O
= (V
IN
V
IN
) 0.1 (1 + R
G2
/R
G1
)
+
TOTAL GAIN
A2 GAIN
R
G1
R
G2
R
B
(V/V)
(V/V)
(
)
(
)
(
)
0.1
1
(None)
10k
--
0.2
2
20k
20k
--
0.5
5
12.4k
49.9k
--
1
10
11.0k
100k
--
2
20
10.5k
200k
--
5
50
10.2k
499k
--
10
100
10.2k
1M
--
20
200
499
100k
9.53k
50
500
100
49.9k
10k
100
1000
100
100k
10k
STANDARD 1% RESISTORS
0.1
F
9
INA146
FIGURE 2. Optional Offset Trim Circuit.
V
IN
+
V
O
1
A1
V
IN
100
10k
Offset Adjustment Range =
15mV, RTI
(
1.5mV at pin 1)
R
T
100k
10
100k
+15V
V
O1
15V
R
3
R
1
R
2
R
5
A2
R
4
5
6
NOTE: Increasing the trim resistor
R
T
will decrease the trim range
V
O
= 1.08V nominal
Output scaled to low
voltage A/D converter.
+5V
40V
+7V
60V
+10V
95V
11V
100V
V+
+5V
1
4
8
Load
R
G2
10k
10k
INA146
5
7
6
2
Differential measurement at
battery rejects voltage drop
in connection resistance, R
X
.
3
V
IN
R
X
R
X
10.8V
+
V+
Max V
IN
FIGURE 3. Measuring Voltages Greater than Supply Voltage.
OFFSET TRIM
The INA146 is laser-trimmed for low offset voltage and
drift. Most applications require no external offset adjust-
ment. Figure 2 shows an optional circuit for trimming the
offset voltage. A voltage applied to the Ref terminal will
be summed with the output signal. This can be used to null
offset voltage. To maintain good common-mode rejection,
the source impedance of a signal applied to the Ref
terminal should be less than 10
and a resistor added to
the positive input terminal should be 10 times that, or
100
. Alternatively, the trim voltage can be buffered with
an op amp such as the OPA277.
INPUT IMPEDANCE
The input impedance of the INA146 is determined by the
input resistor network and is approximately 100k
. The
source impedance at the two input terminals must be nearly
equal to maintain good common-mode rejection. A 12
mismatch in impedance between the two inputs will cause
the typical common-mode rejection to be degraded to ap-
proximately 72dB. Figure 7 shows a common application
measuring power supply current through a shunt resistor.
The source impedance of the shunt resistor, R
S
, is balanced
by an equal compensation resistor, R
C
.
Source impedances greater than 800
are not recommended,
even if they are perfectly matched. Internal resistors are laser
trimmed for accurate ratios, not to absolute values. Adding
equal resistors greater than 800
can cause a mismatch in
the total resistor ratios, degrading CMR.
10
INA146
FIGURE 4. Noise Filtering.
FIGURE 5. Output Clamp.
FIGURE 6. Precision Clamp.
V
O
1
8
6
V
IN
G = 1
Pole at
106Hz
R
G1
10k
10k
R
G2
1M
22nF
INA146
5
2
3
1500pF
Pole at
720Hz
V
IN
+
V
O
1
8
6
R
G2
10k
10k
Output clamps at
approximately
4V.
1N914
1N4684 (3.3V)
INA146
5
2
3
V
IN
V
IN
+
V
O
1
8
6
R
G2
10k
R
1
R
2
R
3
R
4
10k
5.0V
or analog-to-digital V
S
0V
V
O
5V
NOTE: (1) 1/2 OPA2342 with V
S
connected to +5V and GND.
Voltage
Reference
1N914
INA146
5
2
3
V
IN
V
IN
+
(1)
1N914
(1)
11
INA146
FIGURE 7. Current Monitor, G = 1.
FIGURE 8. Comparator Output with Optional Hysteresis Application to Sense Lamp Burn-Out.
FIGURE 9. AC Coupling (DC Restoration).
FIGURE 10. Precision Current Source.
V
O
1V 50mV
+5V
1
Ref
4
8
6
8.4k
INA146
5
7
Feedback
2
3
10M
8k
10k
1V
2k
Lamp
24V
SHUNT
R-I Lamp/10
e.g., 0.1
for 1A
V
O
V
O1
1
8
6
R
G1
11k
R
C
100
R
S
100
R
G2
100k
INA146
5
2
Power
Supply
Load
3
For sense resistors (R
S
)
greater than 10
, use
series compensation
resistor (R
C
) for good
common-mode rejection.
Sense resistors greater
than 500
are not
recommended.
V
O
1
R
G1
11k
R
G2
100k
R
1
1M
INA146
OPA277
5
2
3
C
1
0.1
F
V
IN
V
IN
+
Pole at
f = = 1.6Hz
1
2
R
1
R
C
V
O
I
OUT
(V
IN
V
IN
)/10k
V
O1
1
8
6
R
G2
10k
10k
INA146
5
2
3
V
IN
+
V
IN
+
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