VOUT

RESET

ALERT

IN+

IN-

VS+

GND

CMPIN

CMPREF

10 k:

+

-

0 V to 26 V

+

-

G = 20, 50,

100, 200

ADC

GPIO

GPIO

R1

R2

Microcontroller

5V

2.7 V to 5.5 V

Load

INA381

Copyright © 2017, Texas Instruments Incorporated

7

INA381

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SBOS848 – DECEMBER 2017

Product Folder Links: INA381

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Copyright © 2017, Texas Instruments Incorporated

7 Detailed Description

7.1 Overview

The INA381 is a zero-drift topology, current-sensing amplifier with an integrated comparator that can be used in

both low-side and high-side current-sensing and protection applications. These specially-designed, current-

sensing amplifiers are able to accurately measure voltages developed across current-sensing resistors (also

known as current-shunt resistors) on common-mode voltages that far exceed the supply voltage powering the

device. Current can be measured on input voltage rails as high as 26 V, and the device can be powered from

supply voltages as low as 2.7 V. The device can also withstand the full 26-V common-mode voltage at the input

pins when the supply voltage is removed without causing damage.

The zero-drift topology enables high-precision measurements with maximum input offset voltages as low as

150 µV with a temperature contribution of only 1 µV/°C over the full temperature range of –40°C to +125°C. The

low total offset voltage of the INA381 enables smaller current-sense resistor values to be used, and allows for a

more efficient system operation without sacrificing measurement accuracy resulting from the smaller input signal.

The INA381 uses a reference input that allows for a simple method of setting the corresponding current threshold

level for the device to use for out-of-range comparison. Combining the precision measurement of the current-

sense amplifier and the on-board comparator enables an all-in-one overcurrent detection device. This

combination creates a highly-accurate solution that is capable of fast detection of out-of-range conditions and

allows the system to take corrective actions to prevent potential component or system-wide damage.

7.2 Functional Block Diagram