INA821 datasheet(21/41 Pages) TI1

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INA821

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SBOS893A – AUGUST 2018 – REVISED DECEMBER 2018

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8.3.1.1 Gain Drift

The stability and temperature drift of the external gain setting resistor (RG) affects gain. The contribution of RG to

gain accuracy and drift is determined from Equation 1.

The best gain drift of 5 ppm/

℃ (maximum) is achieved when the INA821 uses G = 1 without RG connected. In

this case, gain drift is limited by the slight mismatch of the temperature coefficient of the integrated 10-kΩ

resistors in the differential amplifier (A3). At gains greater than 1, gain drift increases as a result of the individual

drift of the 24.7-kΩ resistors in the feedback of A1 and A2 relative to the drift of the external gain resistor (RG.)

The low temperature coefficient of the internal feedback resistors significantly improves the overall temperature

stability of applications using gains greater than 1 V/V over alternate options.

Low resistor values required for high gain make wiring resistance important. Sockets add to the wiring resistance

and contribute additional gain error (such as a possible unstable gain error) at gains of approximately 100 or

greater. To ensure stability, avoid parasitic capacitance of more than a few picofarads at RG connections. Careful

matching of any parasitics on the RG pins maintains optimal CMRR over frequency; see Figure 17.

INA821 Datasheet(PDF) 21 Page - Texas Instruments