9.2.2 Solenoid Drive Current-Sense Application

12 V

INA240

OUT

IN+

IN±

VS

GND

REF2

REF1

5 V

10 m

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Control

Figure 9-5. Solenoid Drive Application Circuit

9.2.2.1 Design Requirements

Challenges exist in solenoid drive current sensing that are similar to those in motor inline current sensing. In

certain topologies, the current-sensing amplifier is exposed to the full-scale PWM voltage between ground and

supply. The INA240 is well suited for this type of application.

9.2.2.2 Detailed Design Procedure

For this application, the INA240 measures current in the driver circuit of a 24-V, 500-mA water valve.

To demonstrate the performance of the device, the INA240A4 with a gain of 200 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.

Alternatively, the reference pins can be tied together and driven with an external precision reference.

A value of 10 mΩ was selected to maintain the analog input within the device limits.

9.2.2.3 Application Curve

Time (20 ms/div)

-6

-6

0

-5

6

-4

12

-3

18

-2

24

-1

30

0

36

1

42

2

48

3

54

4

60

5

66

6

D020

2

Y

2

2

1

1

1

3.50

3.50

Y1

3

2.5

2

1.5

Common-Mode Input Signal

INA240 Output

Figure 9-6. Solenoid Drive Current Sense Input and Output Signals

INA240

SBOS662C – JULY 2016 – REVISED DECEMBER 2021

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