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INA138, INA168

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SBOS122E – DECEMBER 1999 – REVISED DECEMBER 2017

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7.3 Feature Description

7.3.1 Output Voltage Range

The output of the INA1x8 device is a current that is converted to a voltage by the load resistor, RL. The output

current remains accurate within the compliance voltage range of the output circuitry. The shunt voltage and the

input common-mode and power-supply voltages limit the maximum possible output swing. The maximum output

voltage (Vout max) compliance is limited by either Equation 1 or Equation 2, whichever is lower:

Vout max = (V+) – 0.7 V – (VIN+ – VIN–)

(1)

or

Vout max = VIN– – 0.5 V

(2)

7.3.2 Bandwidth

Measurement bandwidth is affected by the value of the load resistor, RL. High gain produced by high values of

RL will yield a narrower measurement bandwidth (see Typical Characteristics). For widest possible bandwidth,

keep the capacitive load on the output to a minimum. Reduction in bandwidth due to capacitive load is shown in

the Typical Characteristics.

If bandwidth limiting (filtering) is desired, a capacitor can be added to the output (see Figure 12). This will not

cause instability.

7.4 Device Functional Modes

For proper operation the INA1x8 devices must operate within their specified limits. Operating either device

outside of their specified power supply voltage range or their specified common-mode range will result in

unexpected behavior and is not recommended. Additionally operating the output beyond their specified limits with

respect to power supply voltage and input common-mode voltage will also produce unexpected results. Refer to

Electrical Characteristics for the device specifications.