FEATURES
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LT1168
Low Power, Single
Resistor Gain Programmable,
Precision Instrumentation Amplifier
DESCRIPTIO
The LT
®
1168 is a micropower, precision instrumentation am-
plifier that requires only one external resistor to set gains of
1 to 10,000. The low voltage noise of 10nV/√Hz (at 1kHz) is
not compromised by low power dissipation (350µA typical for
±15V
supplies). The wide supply range of
±2.3V
to
±18V
allows
the LT1168 to fit into a wide variety of industrial as well as
battery-powered applications.
The high accuracy of the LT1168 is due to a 20ppm maximum
nonlinearity and 0.4% max gain error (G = 10). Previous mono-
lithic instrumentation amps cannot handle a 2k load resistor
whereas the nonlinearity of the LT1168 is specified for loads
as low as 2k. The LT1168 is laser trimmed for very low input
offset voltage (40µV max), drift (0.3µV/°C), high CMRR (90dB,
G = 1) and PSRR (103dB, G = 1). Low input bias currents of
250pA max are achieved with the use of superbeta process-
ing. The output can handle capacitive loads up to 1000pF in
any gain configuration while the inputs are ESD protected up
to 13kV (human body). The LT1168 with two external 5k
resistors passes the IEC 1000-4-2 level 4 specification.
The LT1168 is a pin-for-pin improved second source for the
AD620 and INA118. The LT1168, offered in 8-pin PDIP and
SO packages, requires significantly less PC board area than
discrete op amp resistor designs. These advantages make
the LT1168 the most cost effective solution for precision
instrumentation amplifier applications.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Supply Current: 530µA Max
Meets IEC 1000-4-2 Level 4 (±15kV) ESD Tests
with Two External 5k Resistors
Single Gain Set Resistor: G = 1 to 10,000
Gain Error: G = 10, 0.4% Max
Input Offset Voltage Drift: 0.3µV/°C Max
Gain Nonlinearity: G = 10, 20ppm Max
Input Offset Voltage: 40µV Max
Input Bias Current: 250pA Max
PSRR at A
V
=1: 103dB Min
CMRR at A
V
= 1: 90dB Min
Wide Supply Range:
±2.3V
to
±18V
1kHz Voltage Noise: 10nV/√Hz
0.1Hz to 10Hz Noise: 0.28µV
P-P
Available in 8-Pin PDIP and SO Packages
APPLICATIO S
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Bridge Amplifiers
Strain Gauge Amplifiers
Thermocouple Amplifiers
Differential to Single-Ended Converters
Differential Voltage to Current Converters
Data Acquisition
Battery-Powered and Portable Equipment
Medical Instrumentation
Scales
TYPICAL APPLICATIO
5V
Single Supply* Pressure Monitor
BI TECHNOLOGIES
67-8-3 R40KQ, (0.02% RATIO MATCH)
1
3.5k
3.5k
3
8
R1
G = 200
249Ω
1
2
+
40k
7
REF
LT1168
5
6
20k
3
40k
2
IN
ADC
LTC
®
1286
1
AGND
DIGITAL
DATA
OUTPUT
3.5k
3.5k
–
+
1/2
LT1112
4
–
1168 TA01
NONLINEARITY (100ppm/DIV)
*See Theory of Operation section
U
U
U
Gain Nonlinearity
G = 1000
R
L
= 2k
V
OUT
=
±10V
OUTPUT VOLTAGE (2V/DIV)
1168 TA01a
1168fa
1
LT1168
ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
Supply Voltage ......................................................
±20V
Differential Input Voltage (Within the
Supply Voltage) .....................................................
±40V
Input Voltage (Equal to Supply Voltage) ................
±20V
Input Current (Note 2) .......................................
±20mA
Output Short-Circuit Duration (Note 3) ............ Indefinite
Operating Temperature Range (Note 4) .. – 40°C to 85°C
Specified Temperature Range
LT1168AC/LT1168C (Note 5) ............. – 40°C to 85°C
LT1168AI/LT1168I ............................. – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
Order Options
Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking:
http://www.linear.com/leadfree/
ORDER PART
NUMBER
TOP VIEW
R
G
1
–IN 2
+IN 3
–V
S
4
N8 PACKAGE
8-LEAD PDIP
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 150°C,
θ
JA
= 150°C/ W (N8)
T
JMAX
= 150°C,
θ
JA
= 190°C/ W (S8)
8
–
+
7
6
5
R
G
+V
S
OUTPUT
REF
LT1168ACN8
LT1168ACS8
LT1168AIN8
LT1168AIS8
LT1168CN8
LT1168CS8
LT1168IN8
LT1168IS8
S8 PART MARKING
1168
1168A
1168AI 1168I
Consult LTC Marketing for parts specified with wider operating temperature
ranges.
ELECTRICAL CHARACTERISTICS
SYMBOL
G
PARAMETER
Gain Range
Gain Error
T
A
= 25°C. V
S
=
±15V,
V
CM
= 0V, R
L
= 10k unless otherwise noted.
LT1168AC/LT1168AI
MIN
TYP
MAX
1
0.008
0.04
0.04
0.08
2
10
20
4
20
40
15
40
50
40
10k
0.02
0.4
0.5
0.5
6
20
40
15
40
75
40
200
300
250
LT1168C/LT1168I
MIN
TYP
MAX
1
0.015
0.05
0.05
0.08
3
15
25
5
30
50
20
50
60
80
2.00
0.28
15
220
10
165
5
74
200
1250
15
220
10k
0.03
0.5
0.6
0.6
10
25
60
20
60
90
60
300
450
500
%
%
%
%
ppm
ppm
ppm
ppm
ppm
ppm
µV
µV
pA
pA
µV
P-P
µV
P-P
nV/√Hz
nV/√Hz
pA
P-P
fA/√Hz
GΩ
UNITS
CONDITIONS (Note 6)
G = 1 + (49.4k/R
G
)
G=1
G = 10 (Note 7)
G = 100 (Note 7)
G = 1000 (Note 7)
V
O
=
±10V,
G = 1
V
O
=
±10V,G
= 10 and 100
V
O
=
±10V,
G = 1000
V
O
=
±10V,
G = 1, R
L
= 2k
V
O
=
±10V,G
= 10 and 100, R
L
= 2k
V
O
=
±10V,
G = 1000, R
L
= 2k
Gain Nonlinearity (Notes 7, 8)
V
OST
V
OSI
V
OSO
I
OS
I
B
e
n
Total Input Referred Offset Voltage V
OST
= V
OSI
+ V
OSO
/G
Input Offset Voltage
G = 1000, V
S
=
±5V
to
±15V
Output Offset Voltage
Input Offset Current
Input Bias Current
Input Noise Voltage, RTI
Input Noise Voltage Density, RTI
0.1Hz to 10Hz, G = 1
0.1Hz to 10Hz, G = 1000
f
O
= 1kHz
G = 1, V
S
=
±5V
to
±15V
2.00
0.28
10
165
5
74
300
1250
i
n
R
IN
Output Noise Voltage Density, RTI f
O
= 1kHz (Note 9)
Input Noise Current
f
O
= 0.1Hz to 10Hz
Input Noise Current Density
Input Resistance
f
O
= 10Hz
V
IN
=
±10V
2
U
1168fa
W
U
U
W W
W
LT1168
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
C
IN(DIFF)
C
IN(CM)
V
CM
Differential Input Capacitance
Common Mode Input
Capacitance
Input Voltage Range
f
O
= 100kHz
f
O
= 100kHz
T
A
= 25°C. V
S
=
±15V,
V
CM
= 0V, R
L
= 10k unless otherwise noted.
LT1168AC/LT1168AI
MIN
TYP
MAX
1.6
1.6
LT1168C/LT1168I
MIN
TYP
MAX
1.6
1.6
UNITS
pF
pF
CONDITIONS (Note 6)
G = 1, Other Input Grounded
V
S
=
±2.3V
to
±5V
V
S
=
±5V
to
±18V
1k Source Imbalance,
V
CM
= 0V to
±10V
G=1
G = 10
G = 100
G = 1000
V
S
=
±2.3V
to
±18V
G=1
G = 10
G = 100
G = 1000
V
S
=
±2.3V
to
±18V
R
L
= 10k
V
S
=
±2.3V
to
±5V
V
S
=
±5V
to
±18V
G=1
G = 10
G = 100
G = 1000
G = 1, V
OUT
=
±10V
10V Step
G = 1 to 100
G = 1000
V
REF
= 0V
–V
S
+ 1.9
–V
S
+ 1.9
+V
S
– 1.2
+V
S
– 1.4
–V
S
+ 1.9
–V
S
+ 1.9
+V
S
– 1.2
+V
S
– 1.4
V
V
CMRR
Common Mode
Rejection Ratio
90
106
120
126
103
122
131
135
95
115
135
140
108
128
145
150
350
530
+V
S
– 1.2
+V
S
– 1.3
32
400
200
13
1
85
100
110
120
100
118
126
130
95
115
135
140
108
128
145
150
350
530
+V
S
– 1.2
+V
S
– 1.3
32
400
200
13
1
dB
dB
dB
dB
dB
dB
dB
dB
µA
V
V
mA
kHz
kHz
kHz
kHz
V/µs
µs
µs
kΩ
µA
+V
S
– 1.6
V
PSRR
Power Supply
Rejection Ratio
I
S
V
OUT
Supply Current
Output Voltage Swing
–V
S
+ 1.1
–V
S
+ 1.2
20
–V
S
+ 1.1
–V
S
+ 1.2
20
I
OUT
BW
Output Current
Bandwidth
SR
Slew Rate
Settling Time to 0.01%
0.3
0.5
30
200
60
18
0.3
0.5
30
200
60
18
REFIN
I
REFIN
V
REF
A
VREF
Reference Input Resistance
Reference Input Current
Reference Voltage Range
Reference Gain to Output
–V
S
+ 1.6
+V
S
– 1.6
–V
S
+ 1.6
1
±
0.0001
1
±
0.0001
The
●
denotes the specifications which apply over the 0°C
≤
T
A
≤
70°C temperature range. V
S
=
±15V,
V
CM
= 0V, R
L
= 10k unless
otherwise noted.
SYMBOL PARAMETER
Gain Error
CONDITIONS (Note 6)
G=1
G = 10 (Note 7)
G = 100 (Note 7)
G = 1000 (Note 7)
V
OUT
=
±10V,
G = 1
V
OUT
=
±10V,
G = 10 and 100
V
OUT
=
±10V,
G = 1000
G < 1000 (Note 7)
●
●
●
●
●
●
●
●
MIN
LT1168AC
TYP
0.01
0.40
0.45
0.50
2
7
25
100
MAX
0.03
1.5
1.6
1.7
15
30
60
200
MIN
LT1168C
TYP
0.012
0.500
0.550
0.600
3
10
30
100
MAX
0.04
1.6
1.7
1.8
20
35
80
200
UNITS
%
%
%
%
ppm
ppm
ppm
ppm/°C
1168fa
Gain Nonlinearity
(Notes 7, 8)
∆G/∆T
Gain vs Temperature
3
LT1168
The
●
denotes the specifications which apply over the 0°C
≤
T
A
≤
70°C
temperature range. V
S
=
±15V,
V
CM
= 0V, R
L
= 10k unless otherwise noted.
SYMBOL PARAMETER
V
OST
V
OSI
V
OSIH
V
OSO
V
OSOH
V
OSI
/T
V
OSO
/T
I
OS
I
OS
/T
I
B
I
B
/T
V
CM
Input Offset Voltage
Input Offset Voltage Hysteresis
Output Offset Voltage
Input Offset Drift (RTI)
Output Offset Drift
Input Offset Current
Input Offset Current Drift
Input Bias Current
Input Bias Current Drift
Input Voltage Range
G = 1, Other Input Grounded
V
S
=
±2.3V
to
±5V
V
S
=
±5V
to
±18V
1k Source Imbalance,
V
CM
= 0V to
±10V
G=1
G = 10
G = 100
G = 1000
V
S
=
±2.3V
to
±18V
G=1
G = 10
G = 100
G = 1000
V
S
=
±2.3V
to
±18V
R
L
= 10k
V
S
=
±2.3V
to
±5V
V
S
=
±5V
to
±18V
G = 1, V
OUT
=
±10V
(Note 9)
CONDITIONS (Note 6)
V
OST
= V
OSI
+ V
OSO
/G
●
●
●
●
●
●
●
●
●
●
●
●
ELECTRICAL CHARACTERISTICS
LT1168AC
MIN
TYP
18
3.0
60
30
0.05
0.7
100
0.3
65
1.4
–V
S
+ 2.1
–V
S
+ 2.1
MAX
60
380
0.3
3
400
350
MIN
LT1168C
TYP
23
3.0
70
30
0.06
0.8
120
0.4
105
1.4
MAX
80
500
0.4
4
550
600
UNITS
µV
µV
µV
µV
µV/°C
µV/°C
pA
pA/°C
pA
pA/°C
Total Input Referred Offset Voltage
V
S
=
±5V
to
±15V
(Notes 7, 10)
V
S
=
±5V
to
±15V
(Note 9)
(Note 9)
Output Offset Voltage Hysteresis (Notes 7, 10)
+V
S
– 1.3 –V
S
+ 2.1
+V
S
– 1.4 –V
S
+ 2.1
+V
S
– 1.3
+V
S
– 1.4
V
V
CMRR
Common Mode
Rejection Ratio
●
●
●
●
●
●
●
●
●
●
●
●
●
●
88
100
115
117
102
123
127
129
92
110
120
135
115
130
135
145
390
615
83
97
113
114
98
118
124
126
92
110
120
135
115
130
135
145
390
615
+V
S
– 1.3
+V
S
– 1.5
25
0.48
+V
S
– 1.6
dB
dB
dB
dB
dB
dB
dB
dB
µA
V
V
mA
V/µs
V
PSRR
Power Supply
Rejection Ratio
I
S
V
OUT
Supply Current
Output Voltage Swing
–V
S
+ 1.4
–V
S
+ 1.6
16
0.25
–V
S
+ 1.6
25
0.48
+V
S
– 1.3 –V
S
+ 1.4
+V
S
– 1.5 –V
S
+ 1.6
16
0.25
+V
S
– 1.6 –V
S
+ 1.6
I
OUT
SR
V
REF
Output Current
Slew Rate
Voltage Range
The
●
denotes the specifications which apply over the – 40°C
≤
T
A
≤
85°C temperature range. V
S
=
±15V,
V
CM
= 0V, R
L
= 10k unless
otherwise noted. (Note 8)
SYMBOL PARAMETER
Gain Error
CONDITIONS (Note 6)
G=1
G = 10 (Note 7)
G = 100 (Note 7)
G = 1000 (Note 7)
V
O
=
±10V,
G = 1
V
O
=
±10V,
G = 10 and 100
VO =
±10V,
G = 1000
G < 1000 (Note 7)
●
●
●
●
●
●
●
●
MIN
LT1168AI
TYP
0.014
0.600
0.600
0.600
3
10
30
100
MAX
0.04
1.9
2.0
2.1
20
35
70
200
MIN
LT1168I
TYP
0.015
0.700
0.700
0.700
5
15
35
100
MAX
0.05
2.0
2.1
2.2
25
40
100
200
UNITS
%
%
%
%
ppm
ppm
ppm
ppm/°C
1168fa
G
N
Gain Nonlinearity
(Notes 7, 8)
Gain vs Temperature
∆G/∆T
4
LT1168
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
V
OST
V
OSI
V
OSIH
V
OSO
V
OSOH
V
OSI
/T
V
OSO
/T
I
OS
I
OS
/T
I
B
I
B
/T
V
CM
CMRR
Input Offset Voltage
Input Offset Voltage Hysteresis
Output Offset Voltage
Output Offset Voltage Hysteresis (Notes 7, 10)
Input Offset Drift (RTI)
Output Offset Drift
Input Offset Current
Input Offset Current Drift
Input Bias Current
Input Bias Current Drift
Input Voltage Range
Common Mode
Rejection Ratio
V
S
=
±2.3V
to
±5V
V
S
=
±5V
to
±18V
(Note 9)
(Note 9)
(Notes 7, 10)
The
●
denotes the specifications which apply over the – 40°C
≤
T
A
≤
85°C
temperature range. V
S
=
±15V,
V
CM
= 0V, R
L
= 10k unless otherwise noted. (Note 5)
CONDITIONS (Note 6)
V
OST
= V
OSI
+ V
OSO
/G
●
●
●
●
●
●
●
●
●
●
●
●
MIN
LT1168AI
TYP
MAX
20
3.0
180
30
0.05
0.8
110
0.3
120
1.4
500
+V
S
– 1.3
+V
S
– 1.4
0.3
5
550
500
75
MIN
LT1168I
TYP
25
3.0
200
30
0.06
1
120
0.3
220
1.4
MAX
100
600
0.4
6
700
800
+V
S
– 1.3
+V
S
– 1.4
UNITS
µV
µV
µV
µV
µV/°C
µV/°C
pA
pA/°C
pA
pA/°C
V
V
Total Input Referred Offset Voltage
–V
S
+ 2.1
–V
S
+ 2.1
–V
S
+ 2.1
–V
S
+ 2.1
1k Source Imbalance,
V
CM
= 0V to
±10V
G=1
G = 10
G = 100
G = 1000
V
S
=
±2.3V
to
±18V
G=1
G = 10
G = 100
G = 1000
V
S
=
±2.3V
to
±5V
V
S
=
±5V
to
±18V
●
●
●
●
●
●
●
●
●
●
●
●
●
86
98
114
116
100
120
125
128
–V
S
+ 1.4
–V
S
+ 1.6
15
0.22
–V
S
+ 1.6
90
105
118
133
112
125
132
140
420
650
+V
S
– 1.3
+V
S
– 1.5
22
0.41
+V
S
– 1.6
81
95
112
112
95
115
120
125
–V
S
+ 1.4
–V
S
+ 1.6
15
0.22
–V
S
+ 1.6
90
105
118
133
112
125
132
140
420
650
+V
S
– 1.3
+V
S
– 1.5
22
0.42
+V
S
– 1.6
dB
dB
dB
dB
dB
dB
dB
dB
µA
V
V
mA
V/µs
V
PSRR
Power Supply
Rejection Ratio
I
S
V
OUT
I
OUT
SR
V
REF
Supply Current
Output Voltage Swing
Output Current
Slew Rate
Voltage Range
(Note 9)
●
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
If the input voltage exceeds the supplies, the input current should
be limited to less than 20mA.
Note 3:
A heat sink may be required to keep the junction temperature
below absolute maximum.
Note 4:
The LT1168AC/LT1168C are guaranteed functional over the
operating temperature range of – 40°C and 85°C.
Note 5:
The LT1168AC/LT1168C are guaranteed to meet specified
performance from 0°C to 70°C. The LT1168AC/LT1168C are designed,
characterized and expected to meet specified performance from – 40°C
to 85°C but are not tested or QA sampled at these temperatures. The
LT1168AI/LT1168I are guaranteed to meet specified performance from
– 40°C to 85°C.
Note 6:
Typical parameters are defined as the 60% of the yield parameter
distribution.
Note 7:
Does not include the tolerance of the external gain resistor R
G
.
Note 8:
This parameter is measured in a high speed automatic tester that
does not measure the thermal effects with longer time constants. The
magnitude of these thermal effects are dependent on the package used,
heat sinking and air flow conditions.
Note 9:
This parameter is not 100% tested.
Note 10:
Hysteresis in offset voltage is created by package stress that
differs depending on whether the IC was previously at a higher or lower
temperature. Offset voltage hysteresis is always measured at 25°C, but
the IC is cycled to 85°C I-grade (or 70°C C-grade) or – 40°C I-grade
(0°C C-grade) before successive measurement. 60% of the parts will
pass the typical limit on the data sheet.
1168fa
5
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