-

+

REF

GND

VS

OUT

IN-

IN+

SH-

VIN-

SH+

VIN+

INA250A1, INA250A2, INA250A3, INA250A4

SBOS511B – APRIL 2015 – REVISED DECEMBER 2015

www.ti.com

7 Detailed Description

7.1 Overview

The INA250 features a 2-m

Ω, precision, current-sensing resistor and a 36-V common-mode, zero-drift topology,

precision, current-sensing amplifier integrated into a single package. High precision measurements are enabled

through the matching of the shunt resistor value and the current-sensing amplifier gain providing a highly-

accurate, system-calibrated solution. 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.

7.2 Functional Block Diagram

7.3 Feature Description

7.3.1 Integrated Shunt Resistor

The INA250 features a precise, low-drift, current-sensing resistor to allow for precision measurements over the

entire specified temperature range of –40°C to 125°C. The integrated current-sensing resistor ensures

measurement stability over temperature as well as improving layout and board constraint difficulties common in

high precision measurements.

The onboard current-sensing resistor is designed as a 4-wire (or Kelvin) connected resistor that enables accurate

measurements through a force-sense connection. Connecting the amplifier inputs pins (VIN– and VIN+) to the

sense pins of the shunt resistor (SH– and SH+) eliminates many of the parasitic impedances commonly found in

typical very-low sensing-resistor level measurements. Although the sense connection of the current-sensing

resistor can be accessed via the SH+ and SH– pins, this resistor is not intended to be used as a stand-alone

component. The INA250 is system-calibrated to ensure that the current-sensing resistor and current-sensing

amplifier are both precisely matched to one another. Use of the shunt resistor without the onboard amplifier

results in a current-sensing resistor tolerance of approximately 5%. To achieve the optimized system gain

specification, the onboard sensing resistor must be used with the internal current-sensing amplifier.

12

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