LT1991
Precision, 100µA
Gain Selectable Amplifier
FEATURES
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DESCRIPTIO
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Pin Configurable as a Difference Amplifier,
Inverting and Noninverting Amplifier
Difference Amplifier
Gain Range 1 to 13
CMRR >75dB
Noninverting Amplifier
Gain Range 0.07 to 14
Inverting Amplifier
Gain Range –0.08 to –13
Gain Error <0.04%
Gain Drift < 3ppm/°C
Wide Supply Range: Single 2.7V to Split
±18V
Micropower: 100µA Supply Current
Precision: 50µV Maximum Input Offset Voltage
560kHz Gain Bandwidth Product
Rail-to-Rail Output
Space Saving 10-Lead MSOP and DFN Packages
The LT
®
1991 combines a precision operational amplifier
with eight precision resistors to form a one-chip solution
for accurately amplifying voltages. Gains from –13 to 14
with a gain accuracy of 0.04% can be achieved using no
external components. The device is particularly well suited
for use as a difference amplifier, where the excellent
resistor matching results in a common mode rejection
ratio of greater than 75dB.
The amplifier features a 50µV maximum input offset
voltage and a gain bandwidth product of 560kHz. The
device operates from any supply voltage from 2.7V to 36V
and draws only 100µA supply current on a 5V supply. The
output swings to within 40mV of either supply rail.
The resistors have excellent matching, 0.04% over tem-
perature for the 450k resistors. The matching temperature
coefficent is guaranteed less than 3ppm/°C. The resistors
are extremely linear with voltage, resulting in a gain
nonlinearity of less than 10ppm.
The LT1991 is fully specified at 5V and
±15V
supplies and
from –40°C to 85°C. The device is available in space
saving 10-lead MSOP and low profile (0.8mm) 3mm
×
3mm DFN packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Patent Pending.
APPLICATIO S
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Handheld Instrumentation
Medical Instrumentation
Strain Gauge Amplifiers
Differential to Single-Ended Conversion
TYPICAL APPLICATIO
Rail-to-Rail Gain = 1 Difference Amplifier
5V
50k
150k
V
M(IN)
∆V
IN
V
P(IN)
450k
V
OUT
= V
REF
+
∆V
IN
SWING 40mV TO
EITHER RAIL
R
OUT
<0.1Ω
40
35
PERCENTAGE OF UNITS (%)
–
+
450k
–
450k
150k
50k
4pF
+
LT1991
450k
INPUT RANGE
–0.5V TO 5.1V
R
IN
= 900kΩ
4pF
V
REF
= 2.5V
1991 TA01
U
Distribution of Resistor Matching
450k RESISTORS
LT1991A
30
25
20
15
10
5
0
– 0.04
0
– 0.02
0.02
RESISTOR MATCHING (%)
0.04
1991TA01b
U
U
1991fb
1
LINEAR [ LINEAR INTEGRATED SYSTEMS ]
