INA126, INA2126

9

SBOS062A

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FIGURE 4. Bridge Signal Acquisition—Single 5V Supply.

FIGURE 5. Differential Voltage-to-Current Converter.

OPA177

±1.5nA

OPA130

±20pA

OPA602

±1pA

OPA129

±100fA

INA126

R

G

I

B

R

1

V

IN

–

+

A

1

I

O

Load

I

• G

V

IN

R

1

Ref

✻

✻ Dual version has external sense connection.

40k

Ω

10k

Ω

10k

Ω

40k

Ω

INA126

5

1.2V

4

4

68

2

1

8

3

7

6

R

G

R

1

1k

Ω

C

1

0.47

µF

R

2

1k

Ω

+5V

R

340Hz LP

Bridge

Sensor

2.5V –

∆V

2.5V +

∆V

REF1004C-1.2

33

µA

2

3

1

+IN

–IN

V

REF

D

ADS7817

12-Bit

A/D

C

S

Ck

6

Serial

Data

Chip

Select

INA126 and ADS7817

are available in fine-pitch

MSOP-8 package

✻ Dual version has external

sense connection. Pin numbers

shown are for single version.

Clock

5

7

4

8

A

2

A

1

The ADS7817’s V

conversion rate of 10kS/s or slower assures enough current to turn on the

reference diode. Converter input range is

±1.2V. Output swing limitation of

INA126 limits the A/D converter to somewhat greater than 11 bits of range.

A similar instrumentation amplifier, INA125, provides

an internal reference voltage for sensor excitation

and/or A/D converter reference.

✻