7.2.7 Low-Voltage Operation

The INA2128 can be operated on power supplies as low as ±2.25 V. Performance remains excellent with power

supplies ranging from ±2.25 V to ±18 V. Most parameters vary only slightly throughout this supply voltage

range—see Section 6.6. Operation at very low supply voltage requires careful attention to make sure that

the input voltages remain within the linear range. Voltage swing requirements of internal nodes limit the input

common-mode range with low power-supply voltage. Typical performance curves, Figure 6-5 and Figure 6-6,

show the range of linear operation for ±15-V, ±5-V, and ±2.5-V supplies.

7.2.8 Input Protection

The inputs of the INA2128 are individually protected for voltages up to ±40 V. For example, a condition of –40 V

on one input and +40 V on the other input will not cause damage. Internal circuitry on each input provides low

series impedance under normal signal conditions. To provide equivalent protection, series input resistors would

contribute excessive noise. If the input is overloaded, the protection circuitry limits the input current to a safe

value of approximately 1.5 mA to 5 mA. The typical performance curve “Input Bias Current vs Common-Mode

Input Voltage” shows this input current limit behavior. The inputs are protected even if the power supplies are

disconnected or turned off.

Figure 7-4. Two-Axis Bridge Amplifier

INA2128

SBOS035B – DECEMBER 1995 – REVISED MAY 2023

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