INA4181A1IPWR.B datasheet(18/62 Pages) TI2

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7.3 Feature Description

7.3.1 High Bandwidth and Slew Rate

The INAx181 support 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, make the

INAx181 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, where the INAx181 are used with an external

comparator and a reference to quickly detect when the sensed current is out of range.

7.3.2 Bidirectional Current Monitoring

The INA181 senses current flow through a sense resistor in both directions. The bidirectional current-sensing

capability is achieved by applying a voltage at the REF pin to offset the output voltage. A positive differential

voltage sensed at the inputs results in an output voltage that is greater than the applied reference voltage;

likewise, a negative differential voltage at the inputs results in output voltage that is less than the applied

reference voltage. The output voltage of the current-sense amplifier is shown in Equation 1.

OUT

LOAD

SENSE

REF

GAIN

(1)

where

• ILOAD is the load current to be monitored.

• RSENSE is the current-sense resistor.

• GAIN is the gain option of the selected device.

• VREF is the voltage applied to the REF pin.

7.3.3 Wide Input Common-Mode Voltage Range

The INAx181 support input common-mode voltages from –0.2 V to +26 V. Because of the internal topology,

the common-mode range is not restricted by the power-supply voltage (VS) as long as VS stays within the

operational range of 2.7 V to 5.5 V. The ability to operate with common-mode voltages greater or less than VS

allow the INAx181 to be used in high-side, as well as low-side, current-sensing applications, as shown in Figure

7-4.

Bus Supply

±0.2 V to +26 V

High-Side Sensing

Low-Side Sensing

LOAD

Common-mode voltage (VCM)

is bus-voltage dependent.

Common-mode voltage (VCM)

is always near ground and is

isolated from bus-voltage spikes.

Direction of Positive

Current Flow

IN+

Direction of Positive

Current Flow

RSENSE

IN±

IN+

IN±

Figure 7-4. High-Side and Low-Side Sensing Connections

INA181, INA2181, INA4181

SBOS793H – APRIL 2017 – REVISED NOVEMBER 2023

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