8 Detailed Description

8.1 Overview

The INA241x is a high or low-side biirectional, high-speed current-sense amplifier that offers a wide common-

mode range, precision, zero-drift topology, excellent common-mode rejection ratio (CMRR), and features

enhanced pulse width modulation (PWM) rejection at the inputs of the device. Enhanced PWM rejection reduces

the effect of common-mode transients that can propagate to the output signal that are associated with PWM

input signals. Multiple gain versions are available to allow for the optimization of the desired full-scale output

voltage based on the target current range expected in the application.

8.2 Functional Block Diagram

+

t

REF2

REF1

VS

GND

OUT

IN+

IN±

PWM

Rejection

8.3 Feature Description

8.3.1 Amplifier Input Common-Mode Signal

The INA241x supports large input common-mode voltages from –4 V to +110 V. The internal topology of the

for the INA241x to be used for both low-side and high-side current-sensing applications that extend beyond the

supply range of 2.7 V to 20 V.

8.3.1.1 Enhanced PWM Rejection Operations

The enhanced PWM rejection feature of the INA241x provides increased attenuation of large common-mode

ΔV/Δt transients. Large ΔV/Δt common-mode transients associated with PWM signals are employed in

applications such as motor or solenoid drive and switching power supplies. Traditionally, large ΔV/Δt common-

mode transitions are handled strictly by increasing the amplifier signal bandwidth, which can increase chip size,

complexity and ultimately cost. The INA241x is designed with high common-mode rejection techniques to reduce

large ΔV/Δt transients before the system is disturbed as a result of these large signals. The high AC CMRR,

in conjunction with signal bandwidth, allows the INA241x to minimize output disturbances and ringing during

common-mode transitions when compared against what a traditional current-sensing amplifier approaches.

8.3.1.2 Input-Signal Bandwidth

The INA241x is available with several gain options including 10 V/V, 20 V/V, 50 V/V, 100 V/V, and 200 V/V.

The unique multistage design enables the amplifier to achieve high bandwidth at all gains. This high bandwidth

provides the throughput and fast response that is required for the rapid detection and processing of overcurrent

events.

8.3.1.3 Low Input Bias Current

The INA241x inputs draw a 20-µA (typical) bias current at a common-mode voltage as high as 110 V, which

enables precision current sensing on applications that require lower current leakage. Unlike many high voltage

current sense amplifiers whose input bias currents are proportional to the common-mode voltage, the input bias

current of the INA241x remains flat over the entire common-mode voltage range.

INA241A, INA241B

SBOSA30 – MARCH 2022

www.ti.com

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