1

LT1002

Dual, Matched Precision

Operational Amplifier

Strain Gauge Signal Conditioner with Bridge Excitation

–

+

LT1001

3

10

4

11

13

6

2.0K*

8.2k

LM329

+15V

2

3

6

1002 TA01

2k

4.99k*

2k

–15V

*RN60C FILM RESISTORS

+15V

IN4148

350

Ω BRIDGE

2N2219

REFERENCE OUT

TO MONITORING

A/D CONVERTER

IN4148

100

Ω 5W

100

Ω

5W

10k

ZERO

1

µF

340k*

0 TO 10V

OUT

*

301k

1.1k*

2N2907

–

+

1

–

+

1

GAIN

TRIM

INPUT OFFSET VOLTAGE MATCH (

µV)

–100

70

60

50

40

30

20

10

0

–80

0

40

1002 TA02

–20

80 100

–60 –40

20

60

287 UNITS TESTED

Distribution of Offset Voltage Match

FEATURES

s

Thermocouple Amplifiers

s

Strain Gauge Amplifiers

s

Low level signal processing

s

Medical instrumentation

s

Precision dual limit threshold detection

s

Instrumentation amplifiers

s

Guaranteed low offset voltage

LT1002A

60

µV max

LT1002

100

µV max

s

Guaranteed offset voltage match

LT1002A

40

µV max

LT1002

80

µV max

s

Guaranteed low drift

LT1002A

0.9

µV/°C max

LT1002

1.3

µV/°C max

s

Guaranteed CMRR

LT1002A

110dB min

LT1002

110dB min

s

Guaranteed channel separation

LT1002A

132dB min

LT1002

130dB min

s

Guaranteed maching characteristics

s

Low noise 0.35

µV p-p

The LT

combine excellent individual amplifier performance with tight

matching and temperature tracking between amplifiers.

In the design, processing, and testing of the device, particular

attention has been paid to the optimization of the entire

distribution of several key parameters and their matching.

Consequently, the specifications of even the low cost commer-

cial grade (the LT1002C) have been spectacularly improved

compared to presently available devices.

Essentially, the input offset voltage of all units is less than

80

µV, and matching between amplifiers is consistently beter

than 60

µV (see distribution plot below). Input bias and offset

currents, channel separation, common mode and power suply

rejections of the LT1002C are all specified at levels which were

previsouly attainable only on very expensive, selected grades

of other dual devices. Power dissipation is nearly halved

compared to the most popular precision duals, without ad-

versely affecting noise or speed performance. A by-product of

lower dissipation is decreased warm-up drift. For even better

performance in a single precision op amp, refer to the LT1001

data sheet. A bridge signal conditioning application is shown

below. This circuit illustrates the requirement for both excel-

lent matching and individual amplifier specifications.

, LTC and LT are registered trademarks of Linear Technology Corporation.