8

®

INA156

APPLICATIONS INFORMATION

Figure 1 shows the basic connections required for operation

of the INA156. Applications with noisy or high impedance

power supplies may require decoupling capacitors close to

the device pins, as shown.

The output is referred to the output reference terminal, Ref,

which is normally set to VS/2. This must be a low-imped-

ance connection to ensure good common-mode rejection.

In addition, for the G = 50 configuration, the connection

between pins 1 and 8 must be low-impedance. A connection

impedance of 20

Ω can cause a 0.2% shift in gain error.

OPERATING VOLTAGE

The INA156 is fully specified and guaranteed over the supply

range +2.7V to +5.5V, with key parameters guaranteed over

the temperature range of –55

°C to +125°C. Parameters that

vary significantly with operating voltages, load conditions or

temperature are shown in the Typical Performance Curves.

The INA156 can be operated from either single or dual

power supplies. By adjusting the voltage applied to the

reference terminal, the input common-mode voltage range

and the output range can be adjusted within the bounds

shown in the Typical Performance Curves. Figure 2 shows

a bridge amplifier circuit operated from a single +5V power

supply. The bridge provides a relatively small differential

voltage on top of an input common-mode voltage near 2.5V.

FIGURE 1. Basic Connections.

FIGURE 2. Single-Supply Bridge Amplifier.

Ref

22.2k

Ω

200k

Ω

5k

Ω

Gain Pins Open:

G = 10

External Resistor R

G:

10 < G < 50

Gain Pins Connected:

G = 50

5k

Ω

200k

Ω

22.2k

Ω

4

3

2

5

7

18

V–

0.1

µF

Single Supply

Also drawn in simplified form:

Dual Supply

INA156

INA156

6

1

3

8

2

V

OUT

6

7

4

5

Ref

0.1

µF

V+

V+

V–

DESIRED GAIN

R

G

(V/V)

(

Ω)

10

Open

20

30k

30

10k

40

3.3k

50

Short

G = 10 +

400k

Ω

10k

Ω + R

G

V

IN

–

V

IN

+

A1

A2

V

IN

+

V

IN

–

V

OUT = (VIN – VIN) • G + VREF

+–

Bridge

Sensor

INA156

V

REF

(1)

+5V

3

2

4

5

7

6

V

OUT = 0.01V to 4.99V

(2)

NOTES: (1) V

REF should be adjusted for the desired output level,

keeping in mind that the value of V

REF affects the common-mode

input range. See Typical Performance Curves. (2) For best

performance, the common-mode input voltage should be kept away

from the transition range of (V+) – 1.8V to (V+) – 0.8V.

1

8

V

IN

+

V

IN

–