Table 7-3. Design Parameters

DESIGN PARAMETERS

EXAMPLE VALUE

Power supply voltage

5 V

Common mode voltage range

0 V to 24 V

Maximum sense current

1.5 A

RSENSE resistor

50 mΩ

Gain option

50 V/V

7.2.2 Detailed Design Procedure

The INA281-Q1 is designed to measure current in a typical solenoid application. The INA281-Q1 measures

current across the 50-mΩ shunt that is placed at the output of the half-bridge. The INA281-Q1 measures the

differential voltage across the shunt resistor, and the signal is internally amplified with a gain of 50 V/V. The

output of the INA281-Q1 is connected to the analog-to-digital converter (ADC) of an MCU to digitize the current

measurements.

Solenoid loads are highly inductive and are often prone to failure. Solenoids are often used for position control,

precise fluid control, and fluid regulation. Measuring real-time current on the solenoid continuously can indicate

premature failure of the solenoid which can lead to a faulty control loop in the system. Measuring high-side

current also indicates if there are any ground faults on the solenoid or the FETs that can be damaged in an

application. TheINA281-Q1, with high bandwidth and slew rate, can be used to detect fast overcurrent conditions

to prevent the solenoid damage from short-to-ground faults.

7.2.2.1 Overload Recovery With Negative VSENSE

The INA281-Q1 is a unidirectional current-sense amplifier that is meant to operate with a positive differential

input voltage (VSENSE). If negative VSENSE is applied, the device is placed in an overload condition and requires

time to recover once VSENSE returns positive. The required overload recovery time increases with more negative

VSENSE.

7.2.3 Application Curve

Figure 7-3 shows the output response of a solenoid.

0

10

20

30

40

0

2

4

6

Time (50 ms/div)

VCM

VOUT

Figure 7-3. Solenoid Control Current Response

8 Power Supply Recommendations

The INA281-Q1 power supply can be 5 V, whereas the input common-mode voltage can vary between –4 V to

110 V. The output voltage range of the OUT pin, however, is limited by the voltage on the power-supply pin.

www.ti.com

INA281

SBOSA29A – JUNE 2020 – REVISED NOVEMBER 2023

Copyright © 2023 Texas Instruments Incorporated

Submit Document Feedback

17

Product Folder Links: INA281