IN+

IN±

±0.2 V to +26 V

Power Supply

IN+

IN±

High-side sensing

is bus-voltage dependent.

Low-side sensing

is always near ground and is

isolated from bus-voltage spikes.

Load

GND

14

INA381-Q1

SLYS041 – MARCH 2020

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7.3 Feature Description

7.3.1 Wide Input Common-Mode Voltage Range

The INA381-Q1 supports input common-mode voltages from –0.2 V to +26 V. As a result of the internal topology,

operational range of 2.7 V to 5.5 V. As Figure 40 shows, the ability to operate with common-mode voltages

applications.

Figure 40. High-Side and Low-Side Current Sensing

7.3.2 Precise Low-Side Current Sensing

When used in low-side current-sensing applications, the offset voltage of the INA381-Q1 is less than 150 µV.

The low offset performance of the device has several benefits. First, the low offset allows the device to be used

in applications that must measure current over a wide dynamic range. In this case, the low offset voltage

improves accuracy when the sense currents are on the low end of the measurement range. Another advantage

of low offset voltage is the ability to sense lower voltage drops across the sense resistor accurately, thus allowing

for a lower-value shunt resistor. Lower-value shunt resistors reduce power loss in the current-sense circuit, and

help improve the power efficiency of the end application.

The gain error of the INA381-Q1 is specified to be within 1% of the actual value. As the sensed voltage becomes

much larger than the offset voltage, this gain error becomes the dominant source of error in the current-sense

measurement.

7.3.3 High Bandwidth and Slew Rate

The INA381-Q1 supports small-signal bandwidths as high as 350 kHz, and large-signal slew rates of 2 V/µs. The

ability to detect rapid changes in the sensed current, as well as the ability to quickly slew the output, makes the

INA381-Q1 a good choice for applications that require a quick response to input current changes. One

application that requires high bandwidth and slew rate is low-side motor control, where the ability to follow rapid

changing current in the motor allows for more accurate control over a wider operating range. Another application

that requires higher bandwidth and slew rates is system fault detection. The integrated comparator within the

INA381-Q1 is designed to quickly detect when the sense current is out-of-range, and provide a digital output on

the ALERT pin for quicker and faster responses.