INA823 datasheet(21/40 Pages) TI

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8.3.1.1 Gain Drift

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

RG to gain accuracy and drift is determined from Equation 2.

The best gain drift of 5 ppm/

℃ (maximum) is achieved when the INA823 uses G = 1 V/V without RG connected.

In this case, gain drift is limited by the slight mismatch of the temperature coefficient of the integrated 50-kΩ

resistors in the differential amplifier (A3).

At gains greater than 1 V/V, gain drift increases as a result of the individual drift of the 50-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.

8.3.2 Input Common-Mode Voltage Range

The INA823 linear input voltage range extends from 1 V less than the positive supply to 0.15 V less than the

negative supply, and maintains excellent common-mode rejection throughout this range. The common-mode

range for the most common operating conditions are shown in Figure 8-3. While there are other methods to

calculate the common-mode voltage range, the suggested tool is the Analog Engineers Calculator.

Output Voltage (V)

0.5

1.5

2.5

3.5

4.5

0.5

1.5

2.5

3.5

4.5

VREF = 0 V

VREF = 2.5 V

VS = 5 V, G = 1

Figure 8-3. Input Common-Mode Voltage

vs Output Voltage

Output Voltage (V)

0.5

1.5

2.5

3.5

4.5

0.5

1.5

2.5

3.5

4.5

VREF = 0 V

VREF = 2.5 V

VS = 5 V, G = 100

Figure 8-4. Input Common-Mode Voltage

vs Output Voltage

G = 1, VREF = 0 V

Figure 8-5. Input Common-Mode Voltage

vs Output Voltage

G > 10, VREF = 0 V

Figure 8-6. Input Common-Mode Voltage

vs Output Voltage

A single-supply instrumentation amplifier has special design considerations. To achieve a common-mode

range that extends to single-supply ground, the INA823 employs a current-feedback topology with PNP input

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INA823

SBOSA75B – JULY 2021 – REVISED NOVEMBER 2021

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