7 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.

7.1 Application Information

7.1.1 Offset Trimming

The INA122 is laser trimmed for low offset voltage and offset voltage drift. The voltage applied to the Ref

pin is added to the output signal. This connection must be low-impedance to provide expected common-mode

rejection performance. A resistance of 10Ω in series with the Ref pin causes a typical device to degrade to

approximately 80dB CMR. Most applications require no external offset adjustment using the Ref pin and is

typically grounded.

Figure 7-1 shows an optional circuit for trimming the output offset voltage. An op amp buffer is used to provide

low impedance at the Ref pin to preserve good common-mode rejection.

10k

100µA

½ REF200

–

RG

+IN

+

Ref

IN

OUT

+VS

VS

INA122

100µA

½ REF200

–

+

OPA391

100

100

V+

V

±10mV

Adjustment range

Figure 7-1. Optional Trimming of Output Offset Voltage

INA122

SBOS069A – OCTOBER 1997 – REVISED DECEMBER 2024

www.ti.com

14

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