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INA290

SBOS961 – JUNE 2020

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8 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

8.1 Application Information

The INA290 amplifies the voltage developed across a current-sensing resistor as current flows through the

resistor to the load. The wide input common-mode voltage range and high common-mode rejection of the

INA290 allows use over a wide range of voltage rails while still maintaining an accurate current measurement.

The accuracy of any current-sense amplifier is maximized by choosing the current-sense resistor to be as large

as possible. A large sense resistor maximizes the differential input signal for a given amount of current flow and

reduces the error contribution of the offset voltage. However, there are practical limits as to how large the

current-sense resistor can be in a given application because of the resistor size and maximum allowable power

dissipation. Equation 1 gives the maximum value for the current-sense resistor for a given power dissipation

budget:

where:

•

•

(1)

An additional limitation on the size of the current-sense resistor and device gain is due to the power-supply

the output, both positive and negative output swing limitations must be examined. Equation 2 provides the

where:

•

•

GAIN is the gain of the current-sense amplifier.

•

(2)

the value of the sense resistor and the gain of the device under consideration. If the sense resistor selected for

the maximum power dissipation is too large, then it is possible to select a lower-gain device to avoid positive

swing limitations.

The negative swing limitation places a limit on how small the sense resistor value can be for a given application.

Equation 3 provides the limit on the minimum value of the sense resistor.

where:

•

•

GAIN is the gain of the current-sense amplifier.

•

(3)

Table 3 shows an example of the different results obtained from using five different gain versions of the INA290.

From the table data, the highest gain device allows a smaller current-shunt resistor and decreased power

dissipation in the element.