OPA2188 datasheet(23/43 Pages) TI

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9 Application and Implementation

Note

Information in the following applications sections is not part of the TI component specification,

and TI does not warrant its accuracy or completeness. TI’s customers are responsible for

determining suitability of components for their purposes, as well as validating and testing their design

implementation to confirm system functionality.

9.1 Application Information

The OPAx182 operational amplifiers combine precision offset and drift with excellent overall performance,

making these devices a great choice for many precision applications. The precision offset drift of only 0.005

µV/°C provides stability over the entire temperature range. In addition, the devices combine excellent CMRR,

PSRR, and AOL dc performance with outstanding low-noise operation. As with all amplifiers, applications with

noisy or high-impedance power supplies require decoupling capacitors close to the device pins. In most cases,

0.1-µF capacitors are adequate.

The following application examples highlight only a few of the circuits where the OPAx182 can be used.

9.2 Typical Applications

9.2.1 Strain Gauge Analog Linearization

18 V

±18 V

18 V

±18 V

Strain Gauge

10 k

3.4 M

Vexc

5 V

Vout

OPA2182

Figure 9-1. Bridge Sensor Analog Linearization With the OPA2182

9.2.1.1 Design Requirements

A strain gauge is used to measure an alteration due to external force through the use of electrical resistance

in a Wheatstone-bridge configuration. The Wheatstone bridge is used to precisely measure very low values of

resistances down in the mΩ range. An excitation voltage is applied to the bridge, and the output voltage across

the middle of the bridge is measured. The total change in output voltage is relatively small, typically in the mV

range. Therefore, an op amp is used to amplify the signal. The OPA2182 is designed to construct high-precision

amplification.

Use the following parameters for this design example:

• Use the op-amp linear output operating range, which is usually specified under the AOL test conditions. The

common-mode voltage is equal to the input signal.

• Use an op amp that does not add significant noise to the system or else the small output voltage from the

Wheatstone bridge will be lost.

• The input signal must be gained; therefore, use an op amp with low input offset voltage (VOS)

• The input signal must be gained; therefore, use an op amp with enough open-loop gain to provide the

required amplification

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OPA182, OPA2182, OPA4182

SBOS936D – DECEMBER 2019 – REVISED DECEMBER 2021

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