IN+

IN±

OUT

-

+

Buffer

Current

Feedback

GND

RL

R1

R1

Bias

Load

Load

Supply

11

INA281

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7 Detailed Description

7.1 Overview

The INA281 is a high- or low-side current-sense amplifier that offers a wide common-mode range, precision zero-

drift topology, excellent common-mode rejection ratio (CMRR), high bandwidth, and fast slew rate. Different gain

versions are available to optimize the output dynamic range based on the application. The INA281 is designed

using a transconductance architecture with a current-feedback amplifier that enables low bias currents of 20 µA

with a common-mode voltage of 110 V.

7.2 Functional Block Diagram

7.3 Feature Description

7.3.1 Amplifier Input Common-Mode Signal

The INA281 supports large input common-mode voltages from –4 V to +110 V. Because of the internal topology,

used for both low- and high-side current-sensing applications.

7.3.1.1 Input-Signal Bandwidth

The INA281 –3-dB bandwidth is gain-dependent, with several gain options of 20 V/V, 50 V/V, 100 V/V, 200 V/V,

and 500 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.

performance profile of the device over frequency as output voltage increases for each gain variation. As shown in

with lower device gain options. Individual requirements determine the acceptable limits of error for high-

frequency, current-sensing applications. Testing and evaluation in the end application or circuit is required to

determine the acceptance criteria and validate whether or not the performance levels meet the system

specifications.