9.2 Typical Applications

The INA240 offers advantages for multiple applications including the following:

• High common-mode range and excellent CMRR enables direct inline sensing

• Ultra-low offset and drift eliminates the necessity of calibration

• Wide supply range enables a direct interface with most microprocessors

Two specific applications are provided and include more detailed information.

9.2.1 Inline Motor Current-Sense Application

INA240

OUT

IN+

IN±

VS

GND

REF2

REF1

5 V

40 V

100 PŸ

Copyright © 2016, Texas Instruments Incorporated

Figure 9-3. Inline Motor Application Circuit

9.2.1.1 Design Requirements

Inline current sensing has many advantages in motor control, from torque ripple reduction to real-time motor

health monitoring. However, the full-scale PWM voltage requirements for inline current measurements provide

challenges to accurately measure the current. Switching frequencies in the 50-kHz to 100-kHz range create

higher ΔV/Δt signal transitions that must be addressed to obtain accurate inline current measurements.

With a superior common-mode rejection capability, high precision, and a high common-mode specification, the

INA240 provides performance for a wide range of common-mode voltages.

9.2.1.2 Detailed Design Procedure

For this application, the INA240 measures current in the drive circuitry of a 36-V, 4000-RPM motor.

To demonstrate the performance of the device, the INA240A1 with a gain of 20 V/V was selected for this design

and powered from a 5-V supply.

Using the information in the Adjusting the Output Midpoint With the Reference Pins section, the reference point

is set to midscale by splitting the supply with REF1 connected to ground and REF2 connected to supply. This

configuration allows for bipolar current measurements. Alternatively, the reference pins can be tied together and

driven with an external precision reference.

The current-sensing resistor is sized so that the output of the INA240 is not saturated. A value of 100-mΩ was

selected to maintain the analog input within the device limits.

INA240

SBOS662C – JULY 2016 – REVISED DECEMBER 2021

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