+

±

REF2

REF1

VS

GND

OUT

VS

IN+

IN±

12

INA240

SBOS662A – JULY 2016 – REVISED OCTOBER 2016

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Product Folder Links: INA240

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Copyright © 2016, Texas Instruments Incorporated

Feature Description (continued)

(1)

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

By increasing the current-shunt resistor, the differential voltage is increased across the resistor. Larger input

differential voltages require a smaller amplifier gain to achieve a full-scale amplifier output voltage. Smaller

current-shunt resistors are desired but require large amplifier gain settings. The larger gain settings often have

increased error and noise parameters, which are not attractive for precision designs. Historically, the design

goals for high-performance measurements forced designers to accept selecting larger current-sense resistors

and the lower gain amplifier settings. The INA240 provides 100-V/V and 200-V/V gain options that offer the 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 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

should be considered in addition to the gain and current-shunt value when designing with the INA240.

(1)

PARAMETER

EQUATION

RESULTS

INA240A1

INA240A4

Gain

Gain

—

20 V/V

200 V/V

Ideal maximum differential input voltage

150 mV

15 mV

Current-sense resistor value

15 mΩ

1.5 mΩ

Current-sense resistor power dissipation

2

1.5 W

0.15 W

8.4 Device Functional Modes

8.4.1 Adjusting the Output Midpoint With the Reference Pins

Figure 24 shows a test circuit for reference-divider accuracy. The INA240 output is configurable to allow for

unidirectional or bidirectional operation.

Figure 24. 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

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.