Select R1 as ≥ 1kΩ to optimize accuracy of the circuit. Equation 5 shows the R1:

R2 = R1 × (G−1) = R2 = 1kΩ × (125−1) = 124kΩ

(5)

The maximum common-mode voltage of the application is the same as the maximum voltage on the battery cell

which is at 5V. The minimum common-mode voltage is the discharged battery cell which during manufacturing

flow can be close to 0V. Due to the architecture the limitations for maximum common-mode voltage are simply

given by VIN(min) = (V−) +1.75V and VIN(max) = (V+) − 1.5V, in this example VIN(min)= −8.25V and VIN(max) = 8.5V.

The operating input voltage is at 5V+20mV (maximum) and 0V–20mV (minimum) which is within the allowed

range.

8.2.1.3 Application Curves

Many modern signal-conditioning applications calibrate errors at room temperature. In battery testing systems,

the errors resulting from temperature drifts are more relevant. In an application with the INA630, the change

of resistance due to the temperature coefficient of resistance (TCR) of the external resistor network is most

relevant for the drift performance.

Figure 8-4 shows a calculation of the drift error contribution of the INA630 including the gain error drift and offset

drift performance. To demonstrate the effect of the external resistor network, the drift error contribution for a

10ppm/°C and 25ppm/°C resistor network are shown.

Note: Choosing resistors with good TC tracking can cancel the drift error contribution of the external resistor network.

Figure 8-4. Maximum Drift Error (ppm) vs Temperature Rise (°C)

8.3 Power Supply Recommendations

The nominal performance of the INA630 is specified with a supply voltage of ±15V and midsupply reference

voltage. The device also operates using power supplies from ±2.25V (4.5V) to ±18V (36V) and non-midsupply

reference voltages with excellent performance. Parameters that can vary significantly with operating voltage and

reference voltage are shown in Typical Characteristics.

INA630

SBOSAI8A – MARCH 2025 – REVISED JULY 2025

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