high-gain setting and maintains high-performance levels with offset values below 25 µV. These devices allow for

the use of lower shunt resistor values to achieve lower power dissipation and still meet high system performance

specifications.

Table 8-1 shows an example of the different results obtained from using two different gain versions of the

INA240. From the table data, the higher gain device allows a smaller current-shunt resistor and decreased

power dissipation in the element. The Calculating Total Error section provides information on the error

calculations that must be considered in addition to the gain and current-shunt value when designing with the

INA240.

Table 8-1. RSENSE Selection and Power Dissipation(1)

PARAMETER

EQUATION

RESULTS

INA240A1

INA240A4

Gain

—

20 V/V

200 V/V

VDIFF

Ideal maximum differential input voltage

VDIFF = VOUT / Gain

150 mV

15 mV

RSENSE

Current-sense resistor value

RSENSE = VDIFF / IMAX

15 mΩ

1.5 mΩ

PRSENSE

Current-sense resistor power dissipation

RSENSE × IMAX 2

1.5 W

0.15 W

(1)

Full-scale current = 10 A, and full-scale output voltage = 3 V.

8.4 Device Functional Modes

8.4.1 Adjusting the Output Midpoint With the Reference Pins

Figure 8-2 shows a test circuit for reference-divider accuracy. The INA240 output is configurable to allow for

unidirectional or bidirectional operation.

+

±

REF2

REF1

VS

GND

OUT

VS

IN+

IN±

Figure 8-2. Test Circuit For Reference Divider Accuracy

Note

Do not connect the REF1 pin or the REF2 pin to any voltage source lower than GND or higher than

VS.

The output voltage is set by applying a voltage or voltages to the reference voltage inputs, REF1 and REF2. The

reference inputs are connected to an internal gain network. There is no operational difference between the two

reference pins.

8.4.2 Reference Pin Connections for Unidirectional Current Measurements

Unidirectional operation allows current measurements through a resistive shunt in one direction. For

unidirectional operation, connect the device reference pins together and then to the negative rail (see the

Ground Referenced Output section) or the positive rail (see the VS Referenced Output section). The required

differential input polarity depends on the output voltage setting. The amplifier output moves away from the

referenced rail proportional to the current passing through the external shunt resistor. If the amplifier reference

pins are connected to the positive rail, then the input polarity must be negative to move the amplifier output down

INA240

SBOS662C – JULY 2016 – REVISED DECEMBER 2021

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