Datasheet

INA126, INA2126
9
SBOS062A
www.ti.com
FIGURE 4. Bridge Signal Acquisition—Single 5V Supply.
FIGURE 5. Differential Voltage-to-Current Converter.
A
1
I
B
Error
OPA177 ±1.5nA
OPA130 ±20pA
OPA602 ±1pA
OPA129 ±100fA
INA126
R
G
I
B
R
1
V
IN
–
+
A
1
I
O
Load
I
O
= • G
V
IN
R
1
Ref
✻
✻ Dual version has external sense connection.
40kΩ
10kΩ
10kΩ
40kΩ
INA126
5
1.2V
4
4
68
2
1
8
3
7
6
R
G
R
1
1kΩ
C
1
0.47µF
R
2
1kΩ
+5V
R
1
, C
1
, R
2
:
340Hz LP
Bridge
Sensor
2.5V – ∆V
2.5V + ∆V
REF1004C-1.2
33µA
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
REF
input current is proportional to conversion rate. A
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.
✻